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A WAYNE GRttN PUBLICATION 




Will IBM, Xerox Deliver? 








Now! Color for Your 



• • • 




Introducing COLO/?AMA-50 
Percom's SS-50 Bus Color VDG 



Featuring . . . 

• Eleven display formats including 8-color semigraphics, 4- 
color graphics, 2-color high density graphics and 2-color 
alphanumerics. 

Moreover, two- and four-color displays may be switched 
between primary and complementary color sets under soft- 
ware control or from the keyboard. 

Full graphic resolutions range from 64 x 64 picture elements 
to 256 x 192 picture elements. 

• Instant display control: The COLORAMA-50™ is memory 
mapped: your MPU has direct, instant access to display RAM 
and display control registers. 

• Low-cost Modulator Option for Color TV Interface: The 
COLORAMA-50™ provides for installation of an inexpensive 
RF modulator such as Radio Shack PN 277-122 for operation 
using a color TV. 








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y Static and Dynamic RAM cards — memory expansion 

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controllers 
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\l Versatile prototyping boards. SS-50 and SS-30 bus 
J Field-proven software: monitors, operating systems, 

drivers, editors, assemblers, debuggers and HLLs. 



For quality Percom SS-50 bus products, see your nearby 
authorized Percom dealer. To order direct, call toll-free, 
1-800-527-1 222. Prices and specifications subject to change without 
notice. Prices do not include shipping and handling. 



Mix in Sound: With the 
optional modulator in- 
stalled, you can comple- 
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with software -controlled audio. 



Introductory 
Price 

$219.95 



• Extended Addressing: The COLOft4A#\-50™ is compatible 
with the SS-50A bus and the extended-address SS-50C bus. 
Map the board into any of the sixteen 64-Kbyte banks of the 
1-Mbyte SS-50C address space. The COLO&4MA-50™ card 
"defaults" to the first (lowest) bank for the SS-50A bus. 

• Cassettee I/O Option: Add a few inexpensive components to 
the on -card circuitry provided and use an audio cassette for 
program/data storage. 

• Provision for On-Card Firmware: Put your display operating 
system, cassette control program, etc. right on the COLORA- 
MA-50™ card in a 2516 (5-volt 2716) EPROM. Resides in the 
top 2-Kbyte of the card memory space. 

• Operating Software: Included in the comprehensive users 
manual is a listing of a display operating system and cassette 
controller that may be implemented as a callable subroutine 
function from BASIC or existing operating systems. The 
programs are optionally available in a plug-in ROM for 
just $69.95. 

System Requirements 

The COLOR4MA-50™ is pin- and outline-compatible with the 
Percom System-50™ bus, the SS-50A (SS-50) bus and the 
SS-50C bus. The composite video-sync signal output will directly 
drive a color (or BW) video monitor. The output may be mod- 
ulated for operation with a standard (NTSC) TV set. A modulator 
is not included. The COLOft4MA-50™ card occupies 8-Kbytes 
of memory in the upper half of a 64-Kbyte memory space. 
Included on-card is 1-Kbyte of display RAM which will 
accommodate alphanumeric displays, semigraphic displays and 
two low-density full-graphic displays. For the higher density 
graphic displays, additional display RAM is required. The option- 
al RAM ICs may be installed on the card. 



PERCOM DATA COMPANY, INC. 

1 1220 PAGEMILL RD DALLAS. TX 75243 
(214)340-7081 

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Most small system users think all micro- 
imputers are created equal. And they're 
)ht. If you want performance, convenience, 
:yling, high technology and reliability (and 
ho doesn't?) your micro usually has a price 
ig that looks more like a mini. It seems big 
irformance always means big bucks. But 
)t so with the SuperBrain! 
Standard SuperBrain features include: twin 
wble-density 5%" drives which boast nearly 
1,000 bytes of disk storage - expandable 
10 megabytes. A full 64K of dynamic 
M. A CP/M* Disk Operating System to 
;ure compatibility to literally hundreds of 
iplication packages presently available. And, 
12" non-glare, 24 line by 80 column screen. 



You'll also get a full ASCII keyboard with 
an 18 key numeric pad and individual cursor 
control keys. Twin RS232C serial ports for 
fast and easy connection to a modem or 
printer. Dual Z80 processors which operate 
at 4 MHZ to insure lightning-fast program 
execution. And the list goes on! Feature after 
feature after feature. 

Better yet, the SuperBrain boasts modular 
design to make servicing a snap. A common 
screwdriver is about the only service tool 
you'll ever need. And with the money you'll 
save on purchasing and maintaining the 
SuperBrain, you could almost buy another one. 
For under $3,500, it is truly one of the most 
remarkable microcomputers available anywhere. 



Whether your application is small 
business, scientific, educational or just word 
processing, the SuperBrain is certainly an 
exciting solution to the small computer 
problem. And since you can easily expand it, 
you'll probably never outgrow it. 

Call or write us today for a complimentary 
copy of our "SuperBrain Buyer's Guide." We'll 
show you how you can get big system per- 
formance without having to spend big bucks. 



3 



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MICROCOMPUTING 



PUBLISHER/EDITOR 

Wayne Green 

EXECUTIVE VICE PRESIDENT 

Sherry Smythe 

EDITORIAL MANAGER 

Jeff DeTray 

PUBLICATIONS MANAGER 

Edward Ferman 

MANAGING EDITOR 

Dennis Brisson 

ASSISTANT MANAGING EDITOR 

Susan Gross 
COPY EDITOR 
Eric Moloney 

TECHNICAL EDITORS 

Harold Nelson 
G. Michael Vose 

EDITORIAL ASSISTANTS 

Lise Markus, Linda Stephenson 

ADMINISTRATIVE ASSISTANTS 

Pat Graham, Nancy Noyd 
ASSOCIATE EDITORS 

Robert Baker, Ken Barbier, Frank Derfler, Jr., Rod 
Hallen, Peter Stark, Sherm Wantz 



PRODUCTION MANAGER/PUBLICATIONS 

Nancy Salmon 
ASSISTANT PRODUCTION MANAGER 

Michael Murphy 

ADVERTISING GRAPHICS 

Steve Baldwin, Dennis Christensen, Robert Drew, 

Bruce Hedin, Jane Preston 

PRODUCTION DEPARTMENT 

Joan Ahera Frances Benton, Fiona Davies. 

Linda Drew, Bob Dukette, Sandra Dukette, 

Kenneth Jackson, Pat Mackowsky, Theresa 

Ostebo, Sharon Phinney, Dianne Ritson, 

Deborah Stone, Susan Symonds, Anne 

Vadeboncoeur, Irene Vail, Judi Wimberly, 

Donna Wohlfarth 

PHOTOGRAPHY 

Terrie Anderson, Paul Babich 

William Heydolph, Thomas Villeneuve 

TYPESETTING 

Sara Bedell, Michele DesRochers, David 
Hayward, Stephen Jewett, Mary Kinzel, Kelly 

Smith, Karen Stewart 

DESIGN CONSULTANTS 

Invisible Inc. 

Elaine Cheever, Corporate Designer 

Denzel Dyer, Howard Happ, Laurie MacMlllan, 

Joyce Pillarella, Susan Stevens 

EXECUTIVE ASSISTANT 

Leatrice O'Neil 
ACCOUNTING MANAGER 

Knud Keller 

DIRECTOR OF MARKETING 
603-924-7296 

Debra Boudrieau 

CIRCULATION 

Doris Day, Pauline Johnstone, 

Dion Owens, designer 

BULK SALES MANAGER 

Ginnie Boudrieau 

ASSISTANT TO THE PRESIDENT 

Matthew Smith 

ADVERTISING 
603-924-7138 

Louise Caron, John Gancarz, Susan Martin, 

Hal Stephens, 
Marcia Stone, Office Mgr. 



APPLICATIONS 

62 Take a Byte Out of Your Energy Bills Paul Boudreaux 

Give your home a thorough energy analysis. 



BUSINESS 

148 In Search of the Perfect Z Gene Emory 

Evaluate the performance of your business with Z-charting. 



GENERAL INTEREST 

164 A Salty Saga cariecoiiins 

Sailors go down to the sea, with their micros. 



HARDWARE MODIFICATIONS AND PROJECTS 

32 Everyman's Computer System j McKownssams 

A single-board computer with broad appeal. 

56 Poor Man's Memory Expansion for the OSI johnYoung 

Inexpensive memory expansion for the Superboard II or Challenger C1P. 

76 Printing Wizardry for Your Sorcerer Ernest Bergmann 

Hardware and software to interface a Teletype to your Sorcerer. 

1 32 The Best of Both Worlds Gordon woite 

Let your digital machine tune into the analog world. 

1 74 A Spacesaver for the Bytesaver II George Losey 

Quick and easy modification to put the Bytesaver in its place. 



OSI 
Sorcerer 



PROGRAMMING TECHNIQUES 

50 Popping and Pushing Permutations in BASIC Kenneth wasserman 

An elegant solution to unscramble word puzzles. 

104 Recursion: Solving Age-Old Mysteries Doug MacDonaid 

Use this programming technique to tackle seemingly insolvable puzzles. 

170 More for the XOR Allan Pratt 

A little-known Boolean operation that can be used in a variety of ways. 



PET 



Page 86 




Page 52 



1 



4 Microcomputing, December 1981 



Contents: December 1981 



Volume V 

No. 12 



Superbrain 

Apple 

IBM 

Xerox 

Xerox 



SWTP 



Lawrence Bregoii The Secret World of the Superbrain 

Intertec offers you another choice which is worth considering. 

David Goodfeiiow Data Capture: Who Needs It? 

For use with your Apple for telecommunications. 

g Michael vose IBM Thinks Small 

Their 16-bit Personal Computer will give the micro industry a boost. 

Harold Nelson Another Industry Giant Takes a Micro Step 

Xerox introduces the Information Processor for the business environment 

James Nestor Brand-Name Shopping 

A look at the machine behind the label. 

g Michael vose Japanese Invasion: Part 4 

A wrap-up on the growing Japanese presence in the micro marketplace. 

Dennis Doonan Relief for an Overstuffed SWTP 

The QRC motherboard is the solution to system expansion. 



REVIEWS 
52 

80 

86 

94 



95 



140 



144 



68XX 



Apple 



TUTORIAL 
Peter stark 68XX Secrets 116 

A report on Dynamite and building a 48K 6809 system. 



UTILITY 

Paul Hitchcock Stamp Out REMs 112 

Speed up program execution and free up memory space. 



Publisher's Remarks-6 

Micro Quiz-12 

PETpourri-14 

Dial-up Directory-20 

Computer Blackboard-24 

Micro-Scope-26 

Letters to the Editor-30 

Dealer Directory- 178 



DEPARTMENTS 

Club Notes-180 

Classifieds-180 

1981 lndex-182 

Calendar-214 

New Products-216 

New Software-222 

Software Reviews-228 

Book Reviews-232 

Perspectives-242 



Page 94. 





Page 164. 



This month: 

Microcomputers: Toys or Tools? 

Much has been written (in publications 
such as Time, Business Week and The 
Wall Street Journal) about the signifi- 
cance of the entry of IBM and Xerox into 
the realm of microcomputing. These 
giants have determined that microcom- 
puting has reached a level and rate of 
growth sufficient to find it profitable for 
them to enter the market. How will these 
big-name microcomputers affect sales of 
established microcomputer manufactur- 
ers like Apple and Radio Shack? Regard- 
less of immediate effects, the long-term re- 
sult should be a boon to the entire indus- 
try. This, in fact, is the real question: Will 
the expectations of the industry come 
closer to realization because IBM and 
Xerox are now a part of the industry? 

The entry of major computer companies 
into personal computing should definitely 
have a legitimatizing effect on the in- 
dustry. The general public and. more im- 
portantly, the overall "computer com- 
munity" will have to take a more serious 
look at what we are doing in the microcom- 
puting field, which is rapidly becoming a 
major industry. 

It has been disconcerting to meet recent 
computer science graduates who have 
never worked with microcomputers. Some 
are completely unaware that a microcom- 
puter industry exists. More unsettling is 
the view of many in the computer indus- 
try, manufacturers and consultants, that 
the micro or personal computer is a toy 
that can do nothing serious. 

The new major micro manufacturers 
have not introduced industry-revolutioniz- 
ing products from a technical point of view 
(though IBM's use of the 16-bit 8088 pro- 
cessor with an eight-bit data bus results in 
a machine that should bridge the gap be- 
tween older eight-bit and newer 16-bit mi- 
crocomputers). But will they change the 
industry in other ways? We'll keep you up- 
dated on new software and peripherals for 
their computers. — The Editors 



This month's cover: 

Photo by Lighthearted Studio. Special 
thanks to Computerland of Nashua, NH, 
for their assistance in preparing this 
month's cover. 



Kilobaud Microcomputing (ISSN 0192-4575) is published 
monthly by Wayne Green, Inc., 80 Pine St., Peterborough 
NH 03458. Subscription rates in U.S. are $25 for one year 
and $53 for three years. In Canada: $27 for one year only, 
U.S. funds. Foreign subscriptions (surface mail)— $35 for 
one year only, U.S. funds. Foreign air mail subscriptions 
—$62 for one year only, U.S. funds. Canadian Distributor: 
Micron Distributing, 409 Queen St. West, Toronto, Ontar- 
io, Canada M5V 2A5. In Europe, contact: Monika Nedela, 
Markstr. 3, D-7778 Markdorf, W. Germany. South African 
Distributor: KB Microcomputing, PO Box 782815, Sand- 
ton, South Africa 2146. Second-class postage paid at Pe- 
terborough NH 03458 and at additional mailing offices. 
Phone: 603-924-3873. Entire contents copyright 1981 by 
Wayne Green, Inc. No part of this publication may be re- 
printed or otherwise reproduced without written permis- 
sion from the publisher. 



Microcomputing, December 1981 5 



PUBLISHER'S REMARKS 



By Wayne Green 



Devastating Truth 

About Minis 



Mini Squeeze 

With some amusement I read the arti- 
cle in the Sept. 28 Business Week ex- 
plaining that the minicomputer pioneer- 
ing firms are being hit hard by the grow- 
ing market for microcomputers. A sig- 
nificant number of people have been buy- 
ing $5000 word processors rather than 
the $15,000 models (which do precious 
little more). 

These are the same folks who have 
been walking through the microcomput- 
er section of the NCC exhibits for the last 
three years sneering at the toys. They are 
the same aloof folks who have not both- 
ered to read this magazine and its edi- 
torials warning that just this would be 
happening. . .and soon. 

I predict that there are going to be a lot 
more traumatized minicomputer firms 
and their attendant support software and 
peripheral firms as the word spreads 
about what our microcomputers can do 
. . . and how inexpensively. 

Several factors are ganging up on the 
mini people which can't help but force 
many of them out of business. One of the 

6 Microcomputing, December 1981 



more decisive of these is the general 
media's growing interest in micros, 
which is bringing the word of this low- 
cost computing power to businessmen. 
Aiding that are publications such as our 
new Desktop Computing which tell the 
businessman in plain language what 
these small computers are doing for oth- 
er firms . . . and by extension what they 
can do for him. 

Another important factor is the normal 
human tendency to try to keep the world 
from changing. Most firms go along 
spending 100 percent of their efforts try- 
ing to solve present time problems with 
the result that when a major change in 
technology comes along it can upset 
everything. With emphasis on develop- 
ing some immediately needed software 
or an accessory, and on getting the sales 
department to get a slightly larger share 
of the market, few firms have anyone 
with the time to notice an approach- 
ing catastrophe. 

Add to that the wonderful successes 
most of the mini firms have had, which 
have focused their attention on produc- 
tion and incremental changes in the 





product. The problems have involved 
keeping up with the demand and making 
deliveries, not coping with a competitor 
coming in from left field. 

Minicomputer (and maxi) firms have 
been blinded, too, by the power of their 
equipment. They have not stopped to 
look carefully at the micro growth and 
noticed that these seemingly insignifi- 
cant toys have been growing in their abil- 
ity to tackle real work. Micro manufactur- 
ers have had to endure the overbearing 
attitude of the mini firm people at NCC 
ever since they started trying to show 
their systems. They would come by in 
small groups, making snickering re- 
marks to each other and then go back to 
the main exhibits where they were com- 
fortable with "real" computers. 

The Mini Role 

If the minicomputer firms are going to 
weather the next few years, they are go- 
ing to have to get their people together, 
look closely at microcomputers and fig- 
ure what segment of the market their 
systems fill which micros can't. 

There is both good news and bad news 
for the minis. The bad news is that they 
can expect micros to be used for most of 
the smaller firms around the world. . . 
and thus there is a far larger overall mar- 
ket for micros than for minis. They can 
also expect to lose most of the desktop 
market, even in the larger firms, as busi- 
nessmen opt for a combination comput- 
er/terminal rather than just a terminal. 

The good news is that micros will bring 
computing to everyone, and the need for 
the more powerful mini systems will be 
better recognized. Larger firms will find 
that micros are too slow for their needs 
and move to larger and faster systems. 
Businessmen will be able to do most of 
their work on a micro, but will need a 
host mini for some specialized applica- 
tions such as number crunching, large 
databases, networking and so on. 

Until the mini people take off their 
blinders and put their systems into per- 
spective from the viewpoint of the busi- 



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THINGS TO 
DO WITH YOUR 
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BV MARK SAWUSCH 

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333 pages, written in simple terms, of 
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A PARTIAL LIST OF APPLICATIONS 

Real Estate Evaluation Test Your Typing Speed 



Astrology 
Income Tax 
Speed Reading 
Personality Test 
Statistical Analysis 
Logic Circuit Analysis 
Carpenter and Mechanic's Helper 
General Purpose Clock Timer 



Finances & Investments 

Biorythm 

Energy Efficiency 

Antenna Design 

Letter Writing 

Recipe Index/Calculator 



"OTHER MYSTERIES" 
VOLUME III 

by Dennis Kitsz 

Call now and place your order for this new 
book, "THE CUSTOM TRS-80™ & OTHER 
MYSTERIES", from IJG, Inc. More than 
300 pages, with over 60 photographs, of 
projects for the hardware hobbyist. In- 
cludes schematics, PC layouts, software 
driver code, etc. for such do-it-yourself 
undertakings as high resolution graphics, 
reverse video, realtime clock/calender, 
music synthesis, ROM/RAM additions and 
more! 

THE CUSTOM TRS-80™ $29.00 

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BOOKS 

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MICROSOFT™ BASIC DECODED $24.95 



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A complete checkup for your MODEL I or 
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drives. Tests motor speed, head positioning, 
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complete instruction manual. 

SYSTEM DIAGNOSTICS $24.95 
For MODEL III $29.95 



Single Sided, Soft-Sectored 5 '/i -inch, 
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DISKETTES 

95 

box of 10 

PLAIN JANE ™ 

These are factory fresh, absolutely first 
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PLAIN JANETM Diskettes $19.95 

PLAIN JANE™ <gf}6/ 

Introducing MTC's premium generic 
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ERROR-FREE certified. Invest in GOLD! 

PLAIN JANE™ CW#/ $24.95 

VERBATIMS PREMIUM DISKETTES 

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Seven data-shielding improvements mean 
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These individually, 100% error-free cer- 
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VERBATIM DATALIFE™ DISKETTES 

5 ! /4-inch (box of 10) 

MD525-01 $26.95 

10 boxes of 10 (each box)$25.95 

8-inch FLOPPIES 

Double-Density, FD34-8000 . $43.95 



'RINGS' & 
THINGS 

HUB RING KIT for 5Y*" disks $10.95 

HUB RING KIT for 8" disks $12.95 

REFILLS (50 Hub Rings) $ 5.95 

CLEANING KIT for 5 l A" drives $24.95 

SV^-inch diskette case $3.50 

8 inch diskette case $3.95 

5 1 /4-inch File Box for 

50diskettes $24.95 

8-inch File Box for 

50 diskettes $29.95 



TRS-80 is a trademark of the 

Radio Shack Division of Tandy 

Corporation. DATALIFE is a 

trademark of VERBATIM. PLAIN 

JANE, AIDS I. AIDS III. CALCS III, 

CALCS IV. MERGE III are 

trademarks of MTC 
1981 by Metatechnologies 
Corporation, Inc. 



MOST ORDERS 

SHIPPED WITHIN 

ONE BUSINESS DAY 

Products damaged in 
transit will be exchanged. 



PRICES IN EFFECT 
Dec. 1, 1981 THRU 
December 31, 1981, 

Prices, Specifications, 

and Offerings subject to 

change without notice. 

8112 



WE ACCEPT 

• VISA 

• MASTER CHARGE 

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• MONEY ORDERS 

• COD 



•Add $3.00 for shipping 

& handling 
• $3.00 EXTRA for COD. 
•Ohio residents add 5 l / 2 % 

sales tax 



nessman, they are sailing in dangerous 
waters. Their salesmen are going to have 
a tougher and tougher time pulling a con 
job on businessmen. The firms are going 
to have to have systems which really do 
what they claim. 

Another Wall Crumbleth 

A fair segment of the computer indus- 
try are the DP managers and systems 
analysts. These people are going to have 
to make some major readjustments to 
their way of life if they are going to sur- 
vive in anything but decreasing num- 
bers. One of the tools of their business in 
the past (and present) is the ignorance of 
the average businessman— and execu- 
tive—about computers. This mystique 
has been kept intact through the use of a 
foreign language, used in many cases 
more as a smoke screen than for real 
communications. Magazines such as 
Desktop Computing will soon blow this 
cover, exposing DP managers to some 
searching questions which they will have 
to start trying to answer in plain English. 

Indeed, the data processing profession- 
al who is not thoroughly familiar with 
microcomputers is already out of date. 
Any firm which hires someone to man- 
age its data processing, or information 
management— or any of the other prolif- 
erating buzzword phrases for saying 
essentially the same thing— and does not 
make sure that the person is also an ex- 
pert on microcomputers is asking for 
huge losses of its computer investments. 

Now. I haven't done a specific study of 
the microcomputer literacy of DP people, 
but I do read all of the same magazines 
and papers they do and I'm reasonably 
sure that they, as a group, don't know 
beans about micros. Computerworld is a 
large and successful publication, but the 
attitude I've seen in it has been the same 
one I've seen at NCC— arrogant amuse- 
ment with these insignificant upstarts. 
This can't help but poison the water for 
the professionals who read it every week. 

The other publications read by the DP 
professionals have carried on in the 
same vein, helping them maintain their 
ignorance of microcomputers and their 
capabilities. It feeds on itself, with the 
writers and editors of these journals all 
being a part of the maxi and mini world 
and thus conditioned to ignore the new 
smaller systems. 

School Debacle Too 

Most of the colleges which have been 
teaching computing have built up sys- 
tems based upon maxi or minicomput- 
ers, and the departments which have run 
these systems have been as biased 
against micros as everyone else in the 
computer field. The result has been 
a twisted perspective on the part of 
the students, who merely follow along 
with the same lack of respect for small 
(toy) computers. 

Indeed. I've talked with many of the 

8 Microcomputing, December 1981 



college DP people and found the preju- 
dice against micros impenetrable. Even 
those who happen to get hired by a mi- 
crocomputer publication have not been 
able to get over this bias. 

Last year I talked with several colleges 
about setting up microcomputer courses. 
I found myself up against entrenched DP 
professionals who felt this would really 
be a waste of time for the students. Why 
should they bother to learn about com- 
puters with such limited capabilities? 
One of these professionals had put to- 
gether an Altair computer, so he was 
even more convinced of his position as 
the owner of a microcomputer. 

This attitude is beginning to change, 
but all too slowly for the good of the com- 
puting industry. We need people who 
have perspective on the place of 
microcomputers and minicomputers 
rather than bigotry. The firm hiring a 
new DP person has every right to expect 
an honest evaluation of its DP needs 
which will give it the most computing for 
the money spent. Today the larger firm 
has two and three quarters strikes 
against it in this respect. 



The Microcomputing Reader 

The totals for the reader surveys in the 
May and June issues of this magazine 
are in. Not bad! I'll try to get a detailed 
report available for advertisers and pro- 
spective advertisers, and just cover the 
highlights here. 

Starting with the age of our readers, we 
had the largest group in the 25-35 year 
bracket, with the average age of the read- 
er being 35. From an advertising point of 
view this is just about ideal because this 
is the group with the most money to 
spend. These people are right in the mid- 
dle of their most productive years. 

The annual income — averaging 
$29.250— surprised me. I was also 
amazed to see that 9.8 percent of the 
readers are making over $50,000 a year. 
Seventy-five percent are making over 
$20,000 a year. That helps to explain the 
remarkable success in selling stories we 
hear from advertisers. 

Advertisers will be interested to learn 
that over two-thirds of our readers claim 
that they either make the purchasing de- 
cisions or have influence in these deci- 
sions when it comes to purchasing com- 
puter equipment for their company. How 
much will the average business be 
spending for computing power in the 
next year? If we make a wild guess and 
estimate an average investment of only 
$5000 per business— with our survey 
showing 220,000 readers per issue— 
this would net out at about $61 million 
per month being purchased just via 
our readers. 

If these 147,400 Microcomputing read- 
ers don't see ads for a system, how can 



you expect them to think about it when it 
is recommendation time? That's about 
12,000 microcomputer systems a month 
which are bought for business as a result 
of our readers. That doesn't include the 
systems they are buying for their own use. 

One statistic which surprised me was 
that 22.9 percent of our readers have not 
yet bought a computer. There's a market 
for another 50,000 computers right off 
the bat. If we estimate the average invest- 
ment at $2550 (which was the average 
claimed by our readers), that would point 
to a ripe market of $127 million in sales. 
That's only another $10 million a month 
if we figure to get all of them during the 
next year. But $10 million here and $10 
million there . . . and soon you're begin- 
ning to talk about real money. 

Kilobaud Microcomputing has been 
viewed by many ad managers as being 
hobby-oriented, so I was interested to see 
that about 60 percent of the readers are 
using their systems for other than per- 
sonal computing applications. We did 
start out aimed largely at the hobbyists, 
which is what the market was in 1977. 
When I saw that the new breed of hobby- 
ist was different from the old one, I 
changed the orientation of the magazine 
to satisfy the needs of this new group. I'm 
not sure that the word "hobbyist" is ap- 
plicable, but we do need some definition 
for the person who has bought a comput- 
er and is now deeply involved in learning 
about it. That is the aim of Microcom- 
puting magazine today. 

A survey of the computer systems in 
use by the readers shows some substan- 
tial changes since our survey a year ago. 
Things are changing . . . and rapidly. For 
one thing, the percentage of Apple own- 
ers is catching up with the TRS-80 
owners. Some of this obviously has to do 
with TRS owners changing their alle- 
giance to 80 Microcomputing. Indeed, we 
were a bit worried that the loss of TRS 
readers to 80 might hurt the circulation 
of KM. It did slow the growth down a bit, 
but that's all. 

From the latest survey it looks as if 
we have something over 400,000 differ- 
ent readers for the two magazines. When 
you consider that Byte has about that 
and charges more for ads than our two 
magazines combined, there are some ad- 
vertising bargains available for the 
shrewd buyer. 

Comfortably in third place now is 
Heath, with almost double the percent- 
age of the PET, which has been dropping 
steeply. That's a pity, but with virtually 
no advertising and a discouraged bunch 
of owners as a result, perhaps that was to 
be expected. In fourth place, coming up 
fast, is OSI. Over 12,000 of our readers 
have the OSI systems so far. 

Well, that's enough of that. I'll try to 
have the dry details in our sister publica- 
tion. Microcomputing Industry, a 
smaller magazine sent to the industry 
every month. 



The New Microcomputing 

Well, that's what manufacturers say 
when they make changes in their prod- 
uct. Since we're always making small 
changes in Microcomputing, perhaps we 
should put "new" on the cover every 
month. With a growing number of publi- 
cations covering the microcomputer 
field, it is obviously important for us to 
keep in mind what you. the readers, want 
in a magazine. I've been trying to keep 
Microcomputing aimed at your needs 
and make it worth your while to spend 
the time needed to read it . . . and worth 
the money to buy it. 

With well over a dozen magazines in 
the field, even if you could afford to 
subscribe to all of them you wouldn't 
have the time to read 'em. There's just 
too much information. So. if we are going 
to continue to be worth your time and 
money we have to provide what you need 
—the articles and programs which you 
will find of personal benefit. 

I get every magazine in the field— and I 
try the best I can to read them— so I know 
what they're doing and what position 
they have in the field. I've tried to figure 
out what areas should be covered by my 
four computer publications so I can help 
the editorial staffs select articles which 
are consistent with what you need. 

Starting with our newest magazine. 
Desktop Computing, we have a publica- 
tion aimed at the businessman and edu- 
cator to tell them in plain English what 
microcomputers are able to do . . . and of- 
fer avuncular advice on what goes into 
the selection and purchase of a system. 
This magazine also explains in plain lan- 
guage what all those peripherals and pro- 
grams do for you. 

Then there is 80 Microcomputing, 
which is aimed at the owner of a TRS-80 
computer. It offers extended documenta- 
tion, evaluations of accessories and pro- 
grams which are commercially available, 
plus a very generous supply of the best 
programs we can get . . . with both full 
listings in the magazine plus an available 
cassette dump of these listings. 80 is, I 
think, one of the most successful techni- 
cal publications of all time. In less than 
two years it has gone to over 100,000 cir- 
culation and over 400 pages. Advertisers 
tell us that they've never seen a 
magazine that comes even close in sell- 
ing power, which explains the steady in- 
crease in advertising and magazine size. 
It is not. like Byte, top-heavy with ads, 
running about 40 percent or so to their 
60-70 percent and usually running 
about three times as many articles. 

Microcomputing [Kilobaud) is aimed 
at the relative newcomer to computers, 
the person who has a computer and 
wants to learn as much as possible about 
using it. The documentation available 
from most system manufacturers is 
scanty, so if you are going to get much 
out of your investment in a computer you 

^See List of Advertisers on page 210 



want to get all the information you can 
about using your system. You want to 
know what is available for it in accesso- 
ries and in programs. And, considering 
the cost of packaged software. Microcom- 
puting has a wealth of usable programs. 

The more advanced computer owner, 
computer scientist and data processing 
professional may find my first magazine. 
Byte, a good bet, despite the small 
amount of editorial matter in each issue 
(15-20 percent). It's now published by 
McGraw-Hill. 

In addition to my three main maga- 
zines. I also publish a smaller one for the 
industry called, imaginatively enough. 
Microcomputing Industry. This is sent to 
every known store selling computers, to 
all manufacturers of hardware for micro- 
computers and to all software firms. In 



this magazine I tell dealers how to sell 
and manufacturers how to manufacture, 
and discuss shows, methods of product 
distribution, the inside skinny on adver- 
tising and so on. 

There are specialized publications for 
the Apple, Heath. Sinclair and other sys- 
tems. These smaller magazines have 
some serious problems which are diffi- 
cult to overcome. It is very hard for them 
to get first-rate material because they 
can't possibly meet the article payments 
authors get from the larger-circulation 
magazines. The same goes for the pro- 
grams they publish. People who write 
programs are. like you and me. anxious 
to get all they can out of the work they 
have put in, so they look first for a soft- 
ware publisher who might be able to 
bring them hundreds or even thousands 



SORCERER SOFTWARE 



SUPER ASTEROIDS by Apollo 

'A new era in real time graphic arcade 
games'. 

Never has there been such a captivating and superbly written 
arcade game for the Sorcerer Styled after the well known and 
very popular ASTEROID DELUXE arcade game. SUPER ASTER 
OIDS is destined to become the most popular piece of demonstra 
tion software used by dealers and users alike. Perhaps it is the 
outstanding use of fine line graphics or the silky smooth 
movement Maybe it is the breathtaking speed, dazzling 
explosions, gripping sound effects or simply the challenge of 
avoiding those fire balls from that persistent flying saucer that 
insidiously follows you across the screen. Whatever it is. we 
warn you NOT to purchase this game for fear that you may join 
the ranks of hundreds of other ASTEROID Addicts who. square 
and bleary eyed at 3 am. |ust MUST have ONE more go at trying 
to beat that High Score. 

The object is to guide a small space ship across the screen 
avoiding but shooting asteroids as they glide past. When an 
asteroid is hit, it will break up into many smaller pieces. By 
repeatedly hitting the pieces they will soon disintergrate and 
disappear. If you crash your ship into an asteroid it will break 
into pieces and splinter across the screen in a shower of sparks! 
However, if you manage to stay in one piece, chances are you'll 
soon be pursued by a flying saucer that shoots balls of fire! Best 
that you treat him with care, else you may make his friends 
VERY aggressive. 

Apollo has used a novel but ingenius method of continually 
reprogramming graphics characters and has obtained stunning 
results! All movement is done pixel by pixel but without speed 
loss. Numbers of asteroids, directions, speeds and such like are 
all totally unpredictable If you can show us a piece of software 
that has finer, smoother and faster graphics than SUPER ASTER 
OIOS, we guarantee to refund your money in full! 

Cassette $29.95 
ZAP80 'Secret Code 

Disassembler', by Ian Robinson 

This is far from your average run of the mill disassembler' Other 
than being a mere 4K long, able to disassemble at the speed of 
light and packed with options, ZAP80 will display before your 
very eyes all those unknown instructions ZILOG never talk 
about! Ian has been doing extensive research into the actions of 
the Z80 processor when confronted with the 700 or so undocu 
mented (and so called illegal) code sequences Over 100 of 
these are VERY useful! Did you know you have extra 8 bit 
registers and a complete set of instructions to manipulate them 7 
Did you know about extra rotate instructions? 

ZAP80 will disassemble ANY code sequence Nothing is illegal! It 
will allow you to program with codes that no other disassembler 
can decipher! Think about that .... 

ZAP80 comes with documentation and explanation of all new 
mnemonics used Three versions are supplied that reside in low, 
mid and high memory. Options include ASCII output, screen 
pause and customised printer control. 

Whether you are a serious programmer, a beginner or simply 
curious, ZAP80 is a piece of software you must have Come and 
play a REAL adventure game! 

Cassette $24.95 



HOW TO ORDER: 

ALL PRICES ARE IN AUSTRALIAN DOLLARS. 

One Australian dollar equals 1.16 American and 1.4 
Canadian. All programs come standard on cassette 
but some may be requested on either Micropolis II 
Quad density or VISTA 5%" diskettes for an addi- 
tional cost of $5.00 per diskette. Note that more 
than one program will fit on a diskette. Programs 
available or diskette include CIRCUS, GALAXIANS, 
GROTNIK WARS and ZAP80. 

$2 discount if this form is used. (Photostat will 
suffice). 



PROGRAM PRICE 






Postage within Australia is $1 for initial item 
and 50c for each additional. Outside Australia is 
$2 and 50c. 


Less $2 Discount 


$2.00 


TOTAL 





I enclose, 

(a) Cheque or money order for the above 
amount, or 

(b) My credit card, expiry date 

(Master Charge, Visa, Bankcard, American 

Express, Diners Club) 

No 

My name and address: 

NAME: 

STREET: 

TOWN/CITY: 

POSTCODE: COUNTRY: 



POST THE ABOVE FORM TO: 

sysrem soFTware 



^ 162 



1 KENT STREET, BICTON 

WESTERN AUSTRALIA 6157 

TELEPHONE: ISD (619) STD (09) 339 3842 

Sunday through to Friday. 

Ask for Richard Swannell for personal service. 

We are a dynamic Western Australian enterprise 

whoe sole aim is to bring you the best in Sorcerer 

software. 

A catalogue such as this is produced regularly and 

sent to approximately 2000 interested Sorcerer 

users in all parts of the world. L et us know if you 

wish to be included on our mailing list. 



Microcomputing, December 1981 9 



of dollars for their program. Next they 
look for the larger magazines. Here Mi- 
crocomputing has a decided advantage, 
since programs submitted for it are also 
considered for publication by Instant 
Software, with all the royalties that can 
bring. In general then, once you are past 
Microcomputing, 80 Microcomputing, 
Desktop Computing and Byte, you are 
likely to be reading material that has 
been rejected by the first teams. 

Speaking of Instant Software, our pro- 
gram-publishing division is now round- 
ing out its third year in business. If you 
are a programmer you should keep pub- 
lishing houses such as this in mind. The 
market for packaged software is growing 
rapidly, with predicted sales going into 
the billions within a few years. With none 
of the systems manufacturers doing very 
much in the way of developing software, 
this represents a great opportunity for 
the home programmer to get a piece of 
the action in this amazing new field. 

There is one other important benefit to 
Microcomputing as compared to, say. 
Byte. They have gone to around 200,000 
circulation, which means that the ad 
rates are impossible for smaller firms, the 
ones most likely to give you the newest 
gadgets and best bargains. We have 
aimed at 100,000 circulation (with about 
half the advertising rates) so you will 
have better ads from which to choose. 



Perhaps, if you've picked up Byte, you've 
noticed the difference in the type of 
advertising. 

Between this publication and 80, we, 
too, have 200,000 circulation, only it is 
spread out in two complementary maga- 
zines. Advertisers wanting to reach 
everyone can advertise in both of our 
magazines, reaching as large a reader- 
ship as in Byte. . .only perhaps less 
weighted with data processing profes- 
sionals. Advertisers not selling TRS- 
oriented products can reach their pro- 
spective customers at half the cost . . . 
while TRS products can use 80, again at 
less than half the cost of Byte. Perhaps 
this is why 80 has increased in ad pages 
this year far more than Byte . . . and last 
year also. 

Our editors enjoy the competition with 
Byte and the other micro magazines. 
Remember that many of us here started 
and edited Byte in its early days. Alas, as 
it mentioned in the Wall Street Journal, I 
and the others here are a cross they have 
to bear. Why did I think of Robert Vesco 
and his problems when I read that? 

At any rate, Microcomputing is edited 
to bring you the information you need as 
a microcomputer owner. It's aimed at the 
relative newcomer rather than the scien- 
tist or hardened professional. We have a 
lot of hobbyists reading us . . . and busi- 
nessmen who want to better understand 




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and use their systems. We do cover all 
computer systems, but since 80 goes 
into the TRS in depth, we do not give that 
system equal time here. If you have a 
TRS you really need to keep in touch via 
both magazines. 



SGL WABER Electric A division of SGL Industries, Inc. 
300 Harvard Avenue/Westville, NJ 08093/(609) 456-5400 



Program Theft 

One of our Instant Software dealers in 
New York complained in frustration the 
other day that he really needs only one 
copy of each new program. Once that is 
sold, he claims, within days it is all over 
town, being given away by a chain of 
stores which sell computers. 

It's difficult to tell whether he is right 
about this or whether he may be overre- 
acting to one or two such cases. And if it 
is happening as he says, the question is 
whether this is something cooked up by a 
local group of these stores or whether it is 
a policy of the whole chain. 

Another chap, who was involved with 
a major computer summer camp proj- 
ect put on by a well-known college 
in conjunction with a major comput- 
er manufacturer, claimed that the 
students were given copies of Instant 
Software programs by the instructors as 
part of the course. 

Then we have the case of a recently-re- 
turned Instant Software program which 
was not made by Instant Software. It was 
a forgery. 

In case there is even the slightest ques- 
tion in anyone's mind about this, all In- 
stant Software programs are copyright- 
ed. They are protected by law from being 
copied for sale or even for a gift. It is il- 
legal to make a copy for anyone other 
than yourself. 

The reason for this should be clear to 
anyone involved with computers. You 
know as well as I how much work is in- 
volved in writing a program. You prob- 
ably have only a dim concept of the work 
and expense which goes into distributing 
that program, but the economics of this 
distribution are such that the program- 
mer ends up with a bit over 10 percent of 
the retail price of the program. Believe 
me, if there was any way to make that 
higher we would. That's appreciably 
more than book authors generally get. 

If programs are copied and exchanged, 
this is a loss to the programmer and to 
the program publisher. Each time there 
is a theft like this there is that much 
less chance of more good programs be- 
ing written. 

Since many people are able to rational- 
ize away buying stolen property, wheth- 
er it is a computer, a typewriter, a car 
or a program, obviously just depend- 
ing on honesty for protection is a weak 
plan. In the case of Instant Software 
I have offered a $10,000 reward for infor- 
mation which enables us to get a convic- 
tion of someone copying our copyrighted 
programs. I am serious about it, even 



10 Microcomputing, December 1981 




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Microcomputing, December 1981 11 



though the Whole Earth people have 
called me a fascist for this. 

I figured that it would take something 
substantial to break down the normal 
reluctance to be involved, even when a 
crime is being perpetrated. $10,000 can 
do a lot of things for you . . . such as an 
all-expense paid trip around the world for 
two . . . or a very big microcomputer sys- 
tem. The main purpose of the large re- 
ward was to discourage stores from giv- 
ing away copies of Instant Software pro- 
grams. Also schools, clubs and so on. 

These thefts are not penny -ante, by the 
way. The New York caper has been esti- 
mated to have cost Instant Software in 
the neighborhood of $750,000 in sales so 
far, while that summer camp theft has 
been estimated to be over $500,000. You 
may be sure that should we get someone 
to come forth and testify against a store, a 
manufacturer, a school or a club that the 
damage claims will be substantial. 

Speaking of clubs, if you are a member 
of an unincorporated computer club and 
that club is engaged in swapping pro- 
grams, you should know that you can be 
sued as a member of the club, even if you 
had nothing to do with the program theft. 
If a software publisher sues a club, they 
will, in all probability, go after every 
member of the club . . . and particularly 
be on the lookout for any members with 
assets which will make them more sue- 
able than the others. Incorporated clubs 
are a bit safer, but you are asking for it if 
you belong to any club which engages in 
program theft. 

I am looking for anyone who will come 
forth and bring evidence of the copying of 
any Instant Software package. Copyright 
infringement cases are not difficult to 
prove and there is a long line of court 
cases where large awards have been 
given. Indeed. I know of some map pub- 



lishers who make hundreds of thousands 
of dollars in such awards every year . . . 
mostly from small firms and clubs who 
have innocently used a map in their 
advertising or promotions, but not 
reckoned with the copyright problems. 
The penalties can be stiff ... all out of 
proportion to the crime. 

Before I succumb to pressures from the 
Instant Software people to encode pro- 
grams so they can't be listed ... or even 
go to a system which will require a hard- 
ware gadget as part of the decoding ... I 
think it's worth a big try at getting the 
cooperation of Microcomputing readers. 

Please keep your eyes peeled for any 
program theft. If you run into it I would 
appreciate a letter. If you are chicken and 
are afraid to openly blow the whistle, 
either don't sign the letter or ask for con- 
fidentiality. I would much prefer you go 
for the $ 10,000 and work out a system for 
getting a program copy which will stand 
up in court when we go after the thieves. 
You may want to use a hidden tape re- 
corder (I always have a microrecorder 
with me), a friend with a small camera. . . 
or the cooperation of a friend in testifying. 

The very least we can do at the present 
is make it quite clear that when anyone 
gives or gets a program from a friend, in a 
store, at a club, in school, etc., that both 
parties are well aware that this is a 
theft . . . that the penalties are severe and 
not a casual matter. You may be sure that 
no one is going to enter a suit for any 
small amounts . . . they will be big, even 
against individuals such as school 
children. Just the legal costs alone could 
put a good percentage of the computer 
stores out of business. 

Should you find yourself tempted to 
run off a copy of an Instant Software pro- 
gram for someone, be awfully careful 
that he is not entrapping you for that trip 



around the world for two. He can always 
find new friends, but how often will he 
get a trip like that? 

Anticopy Programs 

There is a need for a good deal more 
work on both the simple hardware solu- 
tion to the copying problem . . . and a 
possible software solution. Perhaps it is 
getting time to just forget about trying to 
work with honest people and prepare 
products to thwart the crooks. Yes, this 
will make it very difficult to ever make 
any changes in the program . . . or to use 
it as a teaching tool to learn more about 
programming. It will also prevent simple 
repairs in case you make a mistake in 
loading. I don't like that any better than 
you . . . but something has to be done. 
What do you suggest? U 

Tax Deductible 

Treasury regulation 1. 162-5 permits 
an income tax deduction for education- 
al expenses undertaken to maintain or 
improve skills required in one's em- 
ployment or business. 

Since computer literacy is a skill re- 
quired in virtually any business these 
days, a subscription to Kilobaud Micro- 
computing or even the purchase of a 
new computer would be tax deductible 
in most instances. 



MICRO QUIZ 



Digital Electronics 

Draw the most simplified circuit (the 
one that minimizes the number of gates 
used) that takes one-bit numbers as in- 
puts and outputs the least significant bit 
of their sum. 

Answer on page 238. 



AUTHORIZED TRS 80 w DEALER #R491 



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Model III, BASIC 




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WE ACCEPT CHECK, MONEY ORDER, OR PHONE ORDERS WITH VISA OR MASTERCARD. SHIPPING 
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C & S ELECTRONICS MART IS AN AUTHORIZED TRS 80 SALES CENTER ST ORE #R491 

12 Microcomputing, December 1981 



Reader Service tor tacing page ^239 



FORTH 



«<FOR/MAT»>™ 

SCREEN EDITOR 

and 



KV 33 Corporation 

P.O. Box 27246 / Tucson, Arizona 85726 



DATA ENTRY SYSTEM 



An absolute must for the 
serious FORTH programmer... 




Current tab over 
value and CP 
location displayed at 
all times. 



Deupdate command 
included along with 
other utilities. 



Works very well with 
memory mapped 
video. 



Maintains its own 64 
byte buffer that never 
changes location. 
Any text transferred 
to it via CTRL- Twill 
remain until system 
shut-down or another 
CTRL-T transfer. 




Message displayed 
when iNsert mode is 
toggled on via 
CTRL-N. 



A special formatted 
list routine included 
for printer output. 



Screen format for the 



List of commands: These commands are for the TeleVideo 912, but 

are very easily modified to match the character 
set or special functions keys on any terminal. 

DEL Delete — Delete character to left and move CP left one position. 
CTRL-L Right arrow — > — CP advances one position to right. 
CTRL-H Left arrow < CP advances one position to left. 

CTRL-G Get character — Character at CP location is erased when all text on 

line to right is moved left one position. The end of line character 

location is blanked out. 
CTRL-I Tab over to next tab location — The tab over count is stored as a 

variable and can be changed to any number between and 63. 

CP will advance to next location each time command is given. 

CTRL-J Down arrow — CP moves down one line and maintains same 
column position. 

CTRL-K Up arrow — CP moves up one line and maintains same column 

position. 
CTRL-E Erase line — Line occupied by CP will be completely erased. 

CTRL-S Spread open — All lines below and including CP line move down 
one line. . .last line is lost. 

CTRL-T Transfer — Transfer the CP line to the editor buffer. . .the editor 
buffer contents will be overwritten. 

CTRL-R Read — Read a copy of the editor buffer into the line occupied by 
CP. . .editor buffer contents remain unchanged. 

CTRL-D Delete and close — All lines below CP move up one line and last line 
is erased to all spaces. . .original line is overwritten. 

CTRL-C Clear — All lines below and including line occupied by CP are 
erased to all spaces. . .total screen is erased if CP is on first line. 

CTRL-B Beginning of line — CP moves to leftmost position on line. 

HOME Home — CP moves to top leftmost position of Forth screen. 

RETURN Return key — Do a carriage return line feed. 

CTRL-Z Zap to end of line — All text from CP to end of line is erased. 

CTRL-F Find — Search screen starting at CP position for a string that 
matches the contents of the editor buffer. (This routine is 
purchased separately.) 

CTRL-N iNsert mode is toggled on or off — Character input at CP location 
will push text on current line to right one position. . .last character 
on line will be lost. . .delete, valid character entry, control-G and 
control-N are the only commands recognized while in iNsert mode 
. . .control-G works the same. . delete not only deletes the 
character to the left, but also moves text from CP to end of line left 
one position. . .control-N will toggle iNsert mode off. 

CTRL-Q Quit editing and return to Forth. 



CP is never allowed 
outside of the 
FORTH screen 
boundary. 



Less than two lines of 
code need to be 
changed to work on 
most any terminal. 
(Clear screen code 
and the XY cursor 
addressing.) 

standard CRT version. 

Three listings included. The first listing is for use with a standard 
CRT terminal. The second and third listings are for use with a 
Memory Mapped Video (16x64 and 24x80). 

The above example reflects a transfer of line 3 to the editor buffer via 
control-T. The editor buffer contents can be read into any line 
occupied by Character-Pointer via control-R. This buffer never 
changes location and its contents are displayed at all times. It is very 
handy for relocating lines or moving lines from one screen to 
another. 

Please note the "NSERT/ON" message displayed at the upper right 
to indicate that the iNsert mode has been toggled on via CTRL-N. 
This message is erased when iNsert mode is toggled off. 

The TAB over count is stored as a variable so it can be changed at 
any time. The current value is always displayed to the right of TAB='. 

CP location is maintained within the boundaries of the Forth screen 
at all times. Its value is always displayed to the right of 'CP='. 

Memory requirements are well under 2K. 

All code conforms to the Forth-79 Standard. Each line of code is fully 
explained and flow-charted (Forth style) for easy modification. 

Bomb proof. . .all unused control codes are trapped. 

Must be used with a CRT that has cursor addressing or with a 
Memory Mapped Video. 

The FINDWD package is sold separately but space has been 
reserved in the EDitor for future insertion. It will prove to be an 
invaluable tool for finding a word or words in a screen or searching a 
wide range of screens. It is fully documented and flow-charted. We 
spent a tremendous amount of time on this routine and have cut the 
search time down to under a second per screen (for a screen that is 
already in memory). 

Send check or money order in the amount of $50.00, payable to 
KV33 Corporation, and receive complete source code, flow-charts, 
documentation, and instructions for bringing up on your system. 

FINDWD package is $35.00. Must have the above screen editor to 
operate. 

Please include extra postage for overseas orders, shipping weight 10 oz. 



e copyright 1981 KV33 Corporation • P.O. Box 27246 • Tucson, Arizona 85726 • (602) 889-5722 



^289 



t^See List of Advertisers on page 210 



Microcomputing, December 1981 13 



PET-POURRI 



By Robert Baker 



VIC Expands 



Its Horizon 



RS-232 

Interface 
Announced 



VIC-20 RS-232 Interface 

Commodore has finally included an 
RS-232 interface in the new VIC-20, after 
several model PET and CBM machines. 
Since the RS-232 is much more common 
than the IEEE-488 interface, you should 
have less trouble finding printers, 
modems and other peripherals to con- 
nect to the VIC. Keep in mind, though, 
that a special adapter cable will probably 
be needed, since Commodore did not use 
a standard RS-232 connector. You 
should take a little time to understand 
how the new interface works before try- 
ing to use it. 

The RS-232 interface has four levels of 
operation: the BASIC level (as seen by the 
program), the buffer system, the operat- 
ing system byte/bit handling, and the 
special hardware required for proper 
voltage levels. 

The BASIC-level interface uses the nor- 
mal BASIC commands: OPEN, CLOSE, 
CMD, INPUT*, GET* PRINT* and the 
reserved variable ST. The operating sys- 
tem byte/bit-level handler runs under 
control of 6522 device timers and inter- 
rupts. The 6522 generates non-maskable 
interrupt (NMI) requests that allow back- 
ground RS-232 processing during nor- 
mal program execution. 

There are special software routines 
within the operating system to prevent 
disruption of data transfers by the 
RS-232 routines. Thus, during cassette 
or serial bus activities data cannot be 
received from RS-232 devices. 

The VIC-20 RS-232 interface is bidirec- 
tional with a 256-byte first-in/first-out 
(FIFO) buffer for each direction. The 
opening of an RS-232 channel allocates 
these 512 bytes of system memory at the 
top of user memory. If there isn't enough 
free space above the BASIC program 
text, no error is indicated, but the pro- 
gram will be damaged. The INPUT* and 

Address correspondence to Robert 
Baker, 15 Windsor Drive, Atco, NJ 08004. 



14 Microcomputing, December 1981 



GET* commands fetch data from the 
receiving buffer while PRINT* and CMD 
commands place data into the transmit- 
ting buffer. The buffer allocation is then 
reversed by a CLOSE command. 

Only one RS-232 channel should be 
open at any time. A second OPEN state- 
ment will reset the buffer pointers, and 
any untransmitted or received data will 
be lost. Also, if an RS-232 channel is to be 
used, the OPEN command should be per- 
formed before any variable or DIM 
statements. The opening of an RS-232 
channel also performs an automatic CLR 
command which will destroy any previ- 
ously defined values. Remember that the 



program will be destroyed if there are less 
than 512 bytes of space available at the 
time of the OPEN statement. 

When the RS-232 channel is opened, 
up to four characters can be sent in the 
filename field of the OPEN statement. 
The first two are the control and com- 
mand register values that determine how 
the interface will function. The last two 
are reserved for future system options 
and should be avoided at present. 

The control register values select the 
number of stop bits (one or two), the 
serial word length (five to eight bits), and 
the data rate (50 to 2400 bits/second), as 
shown in Fig. 1. The command register 



7 6 5 4 3 2 10 











1 


1 STOP BIT 









2 STOP BITS 


1 








J 




DATA WORD LENGTH 






8 BITS 







7 BITS 


1 




6 BITS 


1 




5 BITS 


1 1 



\ I I A 



BAUD RATE 



UNUSED 















USER RATE 











1 


50 








1 





75 








1 


1 


110 





1 








134. 5 





1 





1 


150 





1 


1 





300 





1 


1 


1 


600 













1200 










1 


1800 







1 





2400 







1 


1 


3600 




1 








4800 




1 





1 


7200 




1 


1 





9600 




1 


1 


1 


19200 



NOT IMPLEMENTED 



NOT IMPLEMENTED 
ON VIC 



Fig. 1 . VIC-20 serial port control register. 



PARITY OPTIONS 



/// 



PARITY DISABLED 

NONE GENERATEO/RCVD 


X 


X 





ODD PARITY 
RCVR/XMTR 








1 


EVEN PARITY 
RCVR/XMTR 





1 


1 


MARK TRANSMITTED 
PARITY CHECK DISABLED 


1 





1 


SPACE TRANSMITTED 
PARITY CHECK DISABLED 


1 


1 


1 



v s, * 

UNUSED 


1 y. 






3-LINE 







X- LINE 


1 



HANDSHAKE 



NOTE: X * DON T CARE 



FULL DUPLEX 



HALF OUPLEX 



Fig. 2. VIC-20 serial port command register. 



values select the parity options, full- or 
half-duplex mode and the handshaking 
options, as shown in Fig. 2. 

These figures can be used to easily find 
the correct bit configuration when com- 
puting the control characters to con- 
figure the RS-232 port. You should be 
aware that there is no error checking on 
the control word to detect a non-imple- 
mented bit rate. An illegal value in the 
lower four bits of the control register will 
cause the system output to operate at a 
slow rate (below 50 bps). 

When receiving data, the VIC system 
internal receive buffer will hold 255 char- 
acters before a buffer overflow is indi- 
cated in the RS-232 status (ST). If this oc- 
curs, all characters received while the 
buffer-full condition exists are lost. Keep 
in mind that BASIC is slow in normal 
handling of data, and frequent garbage 
collects by the operating system will 
probably cause the receive buffer to over- 
flow. If you want to input data at high bit 
rates you'll probably need machine-lan- 
guage routines to handle the higher 
speed interfacing. 

The normal GET* and INPUT* com- 
mands are used to fetch data from the re- 
ceive buffer. If a GET # command does 
not find any data in the buffer, a null char- 
acter (•••*) is returned as expected. When 
an INPUT* command is used, the system 
will hang until a non-null character fol- 
lowed by a carriage return is received. 

If the RS-232 CTS or DSR control lines 
disappear during character INPUT # , the 
system will hang until it is restored. This 
is why the GET # command is highly 
recommended for fetching data from the 
VIC serial interface. 

When sending serial data, the output 
buffer can hold 255 characters before a 
full-buffer hold-off happens. The system 
will wait in the output routine until trans- 
mission is allowed or the restore key is 
used to recover the system. 

There is no carriage return/line feed 
delay built into the output channel, so 
some RS-232 printers will not print cor- 
rectly unless some form of hold-off or in- 
ternal buffering is implemented by the 
printer. If an RS-232 CTS handshake sig- 
nal is implemented, the VIC buffer will fill 
and discontinue output until transmis- 
sion is allowed. Or the program can send 
a number of null characters to allow an 
appropriate delay before sending another 
printable character. This was a common 
method used with older Teletypes for 
printing without fancy handshaking 
lines. 

For example, assume you need a one- 
second delay after a carriage return and 
you are using a 300-bits-per-second in- 
terface. With ten bits per character (1 
start + 8 data+ 1 stop), that's 30 charac- 
ters per second. Thus, sending 30 null 
characters following the carriage return 
will insure the printer has time to com- 
plete the operation and will be ready to 
print again. 



If the printer finishes early, the null 
characters are just ignored, since they're 
nonprinting characters. Any characters 
sent while the printer was busy perform- 
ing the carriage return just won't be seen 
by the printer while it's busy. 

When you are through with the serial 
interface, closing the RS-232 file discards 
all data then in the buffers, stops all bit 
transmitting and receiving, sets the 
RS-232 RTS and Sout lines high, and de- 
allocates the RS-232 buffers. You should 
be careful that all data has been transmit- 
ted before closing the channel. One way 
to check this from BASIC is: 

100IFST = OAND(PEEK(37151) AND64)= 1 GOTO 100 
110 CLOSE If* 

As shown here, the RS-232 status reg- 
ister can be read from BASIC using the 
ST variable following an operation to the 
serial channel. However, when ST is read 
the RS-232 status word is cleared. 
Therefore, you should reassign the value 
of ST to another variable if multiple com- 
pares are desired. Fig. 3 shows the mean- 
ing of the individual binary bits in the 



7 6 5 4 3 2 10 

' 



PARITY ERROR 

FRAMING ERROR 

RCVR BUFFER OVERRUN 

(UNUSEO) 

CTS SIGNAL MISSING 

(UNUSEO) 

DSR SIGNAL MISSING 

BREAK DETECTED 



IF BIT = 0. NO ERROR DETECTED 



Fig. 3. RS-232 status register. 

RS-232 status register. Remember that 
the value read is in decimal and must be 
converted accordingly. 

For those who may be interested, I've 
included a list of low memory addresses 
used by the serial interface (see Table 1) 
and information on the various RS-232 
control and signal lines (see Table 2). 

Two Disks 

Having both 4040 and 8050 disks is a 
real luxury, but there is one small draw- 
back. The disk drives are normally set as 



Address 


Hex Dec 


$00A7 


167 


$00A8 


168 


$00A9 


169 


$00AA 


170 


$00 AB 


171 


$00B4 


180 


$00B5 


181 


$00B6 


182 


$00F7 


247 


$00F9 


249 


$0293 


659 


$0294 


660 


$0295 


661 


$0297 


663 


$0298 


664 


$0299 


665 


$029B 


667 



Usage 

Receiver input bit temp storage 

Receiver bit count 

Receiver flag, start bit check 

Receiver byte buffer/assembly location 

Receiver parity bit storage 

Transmitter bit count 

Transmitter next bit to be sent 

Transmitter byte buffer/disassembly location 

Two-byte pointer to receiver buffer base loc 

Two-byte pointer to transmitter buffer base loc 

Pseudo 6551 control reg (see Fig. 1) 

Pseudo 655 1 command reg (see Fig. 2) 

Two-bytes following control and command in file name field 

(for future use) 

RS-232 status register (see Fig. 3) 

Number of bits to send/receive 

Two-bytes equal to time of one-bit cell (based on system 

clock and baud rate) 

Byte index to end of the receiver FIFO buffer 

Table 1 . Low memory addresses for RS-232 interface. 



Pin 6522 Abv 


Description 


Line 


ID Pin 




Interface 


C PBO Sin 


Received data 


3 


X 


D PB1 RTS 


Request to send 


3 


X 


E PB2 DTR 


Data terminal ready 


3 


X 


F PB3 RI 


Ring indicator 






H PB4 DCD 


Received line signal 




X 


J PB5 xxx 


(Unassigned) 






K PB6 CTS 


Clear to send 




X 


L PB7 DSR 


Data set ready 




X 


B CB1 Sin 


Received data 


3 


X 


M CB2 Sout 


Transmitted data 


3 


X 


A GND GND 


Protective ground 


3 


X 


N GND GND 


Signal ground 




X 


Table 2. RS-232 control and signal lines. (6522— 


location $91 10#$911F) 



Microcomputing, December 1981 15 



STANOARO 

DOUBLE POLE -DOUBLE THROW 

(DPDT) SWITCH 



TO 4040 DISK , 
WIRES FROM CUT 
ADDRESSING PAD 



v-~c 



TO 8050 DISK, 
WIRES FROM CUT 
ADDRESSING PAD 



Fig. 5. Disk address select switch. 



disk will be device #9. The switch can be 
mounted wherever convenient. Mine is 
mounted on the back of one disk unit, out 
of harm's way. Maybe someday Commo- 
dore will make it easy for us by adding 
switches for device address selection. 



device #8 on the IEEE bus when shipped 
from the factory. When you have two 
disk drives, one drive has to be changed 
to another device address. You can only 
have one device on the IEEE bus that re- 
sponds to a given bus address. If both 
disk drives are the same type, there's no 
problem — you or the dealer must simply 
change the internal address selection of 
one drive permanently and forget about it. 

If you have two different disk types 
(say, a 4040 and an 8050), then a new 
problem arises. Most current disk soft- 
ware is written so it will only work with 
the disk addressed as device *8. Further- 
more, some programs are only available 
for one particular drive. Modifying a ma- 
jor software product could be a rather 
complicated task, and then you'd have 
separate versions for each disk. You real- 
ly don't want to permanently change the 
device address of either disk, since it 
would impose serious limitations. 

One simple solution is to connect only 
one drive at a time, with both disks still 
set as device #8. This allows you to use 
any software package, but you have the 
inconvenience of having to switch cables 
to use a different disk type. Also, you've 
paid for two separate disks but you can 
only use one at a time. 

I routinely test many different software 
packages that are written for many differ- 
ent configurations, and I've come across 
a much nicer solution that turns out to be 
extremely convenient. Basically, it in- 
volves connecting an external switch to 
one of the internal bus address select 
lines in each disk drive. When wired cor- 
rectly, one disk will be device # 8 while 
the other will be device #9. When the 
switch is changed, the device addresses 
are reversed. Thus, either disk can be the 
primary disk (device # 8) while both disks 
are always available. 

I would strongly recommend having 
your local dealer make any changes in- 
side the disk drive if you're not skilled in 
these matters. Otherwise, be extremely 
careful near the disk drives themselves 



UEI 



VALUE ADDED TO 8 TO 
FORM BUS ADDRESS 




CUT HERE 
TO BREAK THE CONNECTION. 
SOLDER WIRES ON BOTH SIDES 
AND CONNECT TO SWITCH 



Fig. 4. 
16 Microcomputing, December 1981 



as they are very sensitive to dirt, vibra- 
tion, etc. Also, the printed circuit board 
contains MOS devices that can be easily 
damaged by static electricity. It's best to 
leave the work to a trained technician if 
you're in doubt. 

For whoever is doing the modification, 
the IEEE bus address is determined by 
three pads on the printed circuit board. 
They are located to the left of the IC 
marked ,4 UE1" (see Fig. 4), and are in 
roughly the same location in both the 
4040 and 8050 disks. These pads are nor- 
mally shorted on the board, but may be 
cut to change the bus address as desired. 
Each pad has a binary value of 1, 2 or 4, 
as shown in the diagram. By cutting one 
or more of these pads, the corresponding 
value is added to 8 to create the new bus 
address. As expected, the disk must be 
device 8 through 15 on the IEEE bus. 

To connect an external switch, you 
simply cut the bottom pad in both disks 
as shown in Fig. 5. Then carefully solder 
a wire to each side of the cut pad and at- 
tach to the external switch. When the ex- 
ternal switch is closed the disk is device 
*8 as normal. If the switch is open, the 



Hex location New hex data 


H= SCREEN PRINT ROUTINE 


- FIX 


S039D $D3 




N^FROM 
N: 


MRY ' 


81 COLUMN 






$03A4 $D4 




D0384- 


0302 


1 2 


3 


MNC- 


-CODE 


$03CF $20 




I : 6384 
I : 8386 




R2 04 
8E D4 


08 


LDX 
STX 


=$04 
$O0D4 


$03D0 $83 




I : 0389 




20 BR 


F0 


JSR 


$F0BR 


$03D1 $F1 




I : 038C 
I : 038E 




R0 00 

R9 30 




LDY 
LDR 


= $00 

=$80 


$03D2 $60 




I : 039O 




8D 98 


03 


STR 


$0398 


$03D3 $40 

**k ^""k *~X ■ ^ A. *«*k >— * ^-v 




I : 0393 
I : 0396 




8C 9? 
B9 0U 


03 
80 


STY 
LDR 


$0397 
$8000, Y 


$03D4 $20 




I : 0399 




29 7F 




RND 


=$7F 


Table 3. Hexadecimal values for up- 


I = 039B 




18 




CLC 




dating Screen Print assembly-lan- 


I : 039C 
I : 039F 




2C D3 
F0 02 


03 


BIT 
BEG 


$03D3 
$83R3 


guage program. 




I03H1 




69 40 




ROC 


=$40 






I : 03R3 




2C D4 


03 


BIT 


$03D4 






I : 03R6 




DO 02 




BNE 


$03RR 






I : 03A8 




69 40 




RDC 


=$48 






I : 03Rfi 




20 28 


Fl 


JSR 


$F128 






I : ©3RD 
I : 03RE 




C8 
C0 28 




I NY 
CPV 








=$28 


N 
N 


CORRESPONDING MEMORY DUMP 
FOR SCREEN PRINT ROUTINE FIX 




I : 03B6 
I : 03B2 




DO E4 
ft'3 OD 




BNE 
LDR 


$0396 
=$0D 


N 






I : 03B4 




20 28 


Fl 


JSR 


$F128 


ri 


0384-03D4 12 3 4 5 


6 7 


I : 03B7 




R9 OR 




LDR 


=*Ofl 


H 


0384-038B R2 04 8E D4 00 20 


ER FO 


I : 03B9 




20 28 


Fl 


JSR 


$F128 


H 


038C-0393 RO 00 R9 SO SD 98 


03 SC 


I : 03BC 




98 




TYR 




M 


0394-0391 97 03 B9 00 SO 29 


7F IS 


I : 03BD 




13 




CLC 




H 


039C-03R3 2C D3 03 FO 02 69 


40 2C 


I : 03BE 




6D 97 


03 


RDC 


$0397 


M 


03R4-03RB D4 03 DO 02 63 40 


20 28 


I03C1 




3D 97 


03 


STR 


$0397 


M 


03RC-03B3 Fl C8 CO 28 DO E4 


R9 00 


I : 03C4 




90 03 




BCC 


$83C9 


H 


03B4-03BB 20 28 Fl R3 OR 20 


23 Fl 


I : 03C6 




EE 98 


03 


INC 


$0398 


H 


03BC-03C3 98 13 6D 97 03 SD 


97 03 


I : 03C9 




R0 00 




LDY 


= $00 


H 


03C4-03CB 90 03 EE 98 03 RO 


00 C9 


I : 03CB 




C9 E8 




CMP 


=$E8 


H 


03CC-03D3 E8 DO C7 20 S3 Fl 


60 40 


1 : 03CD 




D0 C7 




BNE 


$0396 


W : U3D4-03DB 20 09 00 00 00 00 


00 00 


I : 03CF 
I : 03D2 




20 83 
60 


Fl 


JSR 
RTS 


$F183 


Table 4. Corresponding memory 


Program listing. Screen Print routine 


dump for Screen Print routine fix. 


fix. 















Screen Print Fix 

In the May 1981 column I used a sim- 
ple screen print program as an example 
while talking about machine-language 
programming. I mentioned in the col- 
umn that the method used may not be 
the preferred way to use the IEEE printer 
from a machine-language program, but it 
does work. 

A reader from Italy recently sent in a 
simple change to the routine that elimi- 
nates a minor problem. As written, the 
routine will leave the selected printer 
with the printer's LED on when the rou- 
tine ends. This can be fixed by adding 
one more subroutine call at the end of the 
routine. However, the two constants after 
the routine must be moved and their ref- 
erences fixed to allow for the additional 
instruction. 

To correct the source program, add a 
JSR $7183 instruction just before the 
RTS instruction at the end of the routine. 
This changes the hex locations as shown 
in Table 3. 

I've included new monitor displays and 
a disassembly listing to make things 
easier for those who may want to add 
the changes. □ 



EXCITING NEWS FOR TRS-80" MODEL III USERS! 



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STOCKPAK not only delivers a "stand-alone" Port- 
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Here's How STOCKPAK Will Help You: 

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tions for maximizing the usefulness of the system. 




STOCKPAK SELECTION SYSTEM 



The heart of STOCKPAK is a powerful, analytical 
stock selection tool which enables investors to choose 
stocks which meet their investment criteria. For exam- 
ple, you may wish to select only those oil and gas stocks 
with price/earnings ratios of less than 7 and yields of 6% 
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can store it as a separate data file for continuing use. 

REPORT WRITER 



You can define the report formats you would like to 
see on those stocks meeting your investment objec- 
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PORTFOLIO MANAGEMENT SYSTEM 

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or "sell" decisions. 

HOW TO ORDER STOCKPAK 

STOCKPAK is designed exclusively for TRS-80 
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7/ 



S 60 



Standard & Poor's Corporation 

25 BROADWAY, NEW YORK, NY 10004 (212) 248-3993/3374 



v*See List of Advertisers on page 210 



Microcomputing, December 1981 17 



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DIAL-UP DIRECTORY 



By Frank J. Derfler Jr. 



Modems to 

Keep in TOUCh FromlnayerPrentice 



The Gift of 
Communication 



Christmas is almost here again! This 
month we will look at some terrific hard- 
ware and software you might want to find 
under your tree. We will also look at an- 
other new and interesting use of an infor- 
mation utility. 



A Modem under the Tree? 

Would you like to find a modem under 
your tree? Here are two that can meet 
anyone's needs. I really love my Hayes 
Stack Smartmodem! I described it in de- 
tail in the August 1981 issue, but now I 
have lived with it for a while and I'm still 
impressed. This little box (Photo 1) will 
autodial and auto-answer with any ter- 
minal, or any microcomputer acting as a 
terminal — regardless of the software the 
terminal has inside. 

The Hayes Stack Smartmodem is an 
intelligent peripheral device. You send it 
commands over the ASCII line from the 
keyboard of any terminal device. When it 
is off-line it will respond to a command 
such as AT D703734 1387 by dialing that 
telephone number with rotary dial 
pulses. The "AT" means "wake up, mo- 
dem!" The "D" tells it to rotary dial; a 
"T" would set it for tone dialing. You can 
instruct it to wait and mix dial pulses and 
tone dialing to meet practically any dial- 
ing situation. When it is on-line, you sim- 
ply prefix your commands with an es- 
cape code to get its attention. 

The modem will auto-answer after you 
give it a simple command such as AT 
SO = 3 (answer on the third ring). It will 
wait for the third ring and then welcome 
whoever is calling with an answer tone. 
The speaker built into the SmartModem 
lets you hear the connection being made 
(either dialing or answering), and also op- 
erates under control of the Smartmodem 
software. 

I*m not going to go into all of the details 
of how this device operates, but I will say 
that it should be number one on the 

20 Microcomputing, December 1981 



Christmas list of anyone who uses an RS- 
232C port for data communications. It is 
a well-built, easy-to-use device with full 
operating capabilities. Santa would have 
to pay about $280 for a Smartmodem at 
his local computer store. The elves at 
Hayes Microcomputer Products, 5835 
Peachtree Corners East, Norcross, GA 
30092 can supply more information. 

If you don't need a modem with all of 
those capabilities, the Prentice Star 
would be a nice thing to find under the 
tree with the toy soldiers and the dolls. 
The Prentice Corporation has been in the 
modem business for a long time, but 
most of their products go to the full-time 
heavy-duty communications market. 
The Star represents their new entry into 
the market of modems for personal or 
portable use. As Photo 2 shows, the Star 
is an acoustically-coupled device. It is 
well constructed, with deep cups for the 
telephone handset and a full comple- 
ment of LEDs to show what is happening 
on the circuit. The switches and LEDs 
are conveniently placed in the front of the 
unit. The Star is available for under $130 
from several of the advertisers in Micro- 
computing. It is a commercial-quality 
acoustic modem at a "hobby" price. Con- 
tact Prentice Corporation at 266 Caspian 
Drive, Sunnyvale, CA 94086. 

The Apple II and CP/M 

The CP/M operating system from 
Digital Research has grown in impor- 
tance in the last few months. Xerox is us- 
ing it in their nifty 820 system, and CP/M 
will be available for the IBM Personal 
Computer system despite IBM's accep- 
tance of a different operating system as 
their standard. There are more micro- 
computers now running under CP/M 
than under any other single operating 
system. 

It is only natural that the Apple II com- 
munity would not be left behind simply 
because CP/M is an 8080 operating sys- 



tem and the Apple uses a 6502 CPU. Mi- 
crosoft came to the rescue with their Soft- 
card for the Apple II which actually gives 
that system an extra Z-80 CPU. With the 
Softcard, Apple II users can run all of the 
CP/M software available and still play 
Raster Blaster in their spare time. 

As Apple 11+ CP/M owners grew to 
know and love programs like WordStar, 
they needed to be able to transmit and re- 
ceive their CP/M files through a modem. 
Several capable programs are now enter- 
ing the Apple II + CP/M arena, including 
Crosstalk, which we discussed last 
month. But the first one on the market 
was Z-Term, written by Bill Blue. 

Z-Term 

Bill Blue was (along with Craig 
Vaughan) one of the developers of the or- 
iginal Apple Bulletin Board software. 
Bill's focus has always been on providing 
software with a high degree of "human 
engineering": i.e.. software that's easy to 
use. His ASCII Express package for the 
Apple II has long set the standard for Ap- 
ple terminal software programs. Z-Term 
is not a warmed-over ASCII Express; it is 
better. 

Z-Term is written in 8080 assembly 
language. It has the features normally 
found in a smart terminal program, such 
as the ability to transmit and receive 
standard ASCII text files through a buffer 
(38K bytes in a 56K system) and transmit 
prepared files in either a line-by-line or 
character-by-character mode in response 
to prompts from the other system. 

The program also provides for the use 
of up to 12 macro files which can auto- 
matically dial a telephone number 
(through the Hayes Micromodem II, 
SmartModem, Apple Lynx or the new 
Radio Shack Modem II), and transmit ele- 
ments of information such as sign-on 
codes for the system being entered. Most 
of these capabilities are standard with 
the best terminal programs, but Z-Term I 



also has some features found in very few 
other terminal packages. 

Z-Term can review the buffer while on 
line. The only other program I know of 
that can do this is Omniterm for the 
TRS-80. The ability to look back in the 
buffer is valuable to people using elec- 
tronic mail systems. This feature im- 
proves the quality of electronic message 
exchanges because it lets you look back 
at the messages you have received and 
formulate more meaningful replies. 
Z-Term provides very flexible use of the 
buffer. The buffer can be examined, 
cleared, saved to disk or expanded 



without changing the contents. This is a 
rare and valuable feature. 

Z-Term also has some translation abil- 
ity. Translation, in this case, refers to the 
ability of the program to change a re- 
ceived or transmitted ASCII character to 
a different character. Translation can be 
used to protect a printer from strange 
control codes, and to tailor a microcom- 
puter to perform in certain ways. 

Z-Term can tailor the Apple II to re- 
spond like a specific brand and model 
commercial terminal. This is particularly 
useful when communicating with time- 
sharing systems that have software writ- 




Photo 1 . The Hayes Stack Smartmodem is a complete auto-answer and autodial RS- 
232C modem that needs no software in the terminal to operate at its full 
capabilities. A Z-8 microprocessor runs its own internal program which responds to 
commands sent over the RS-232C data line. 




Photo 2. The Prentice Star modem is a high-quality acoustically coupled device for 
computers with an RS-232C port. It features switchable originate/answer and 
full/half-duplex operation. Various test features and a full set of diagnostic LEDs 
I enhance its operation. 



ten for a particular terminal. 

The Z-Term manual includes informa- 
tion on how to tailor the cursor move- 
ment, screen blanking, reverse video and 
other features to match those of common 
commercial terminals. (These terminal 
emulations require that you have an 
80-eolumn display card in your Apple.) 

Z-Term is flexible in the way it handles 
its menu. The menu usually is not dis- 
played, so the frequent user can zip right 
in and out of commands with little delay. 
If it is needed, however, the menu can be 
called immediately; it provides helpful 
guidance in using the commands. 
Z-Term is one of the best available ter- 
minal programs. 

But Wait! 

But Z-Term, as good as it is, now has a 
"big brother." Bill Blue has written an 
enhanced version of Z-Term called The 
Professional (Z-Pro). At this writing. I 
have not run Z-Pro long enough to award 
it the title of Best Terminal Package, but 
it's a prime contender. Z-Pro contains the 
protocol file transfer capability that 
Z-Term lacks. It also has unique hand- 
shaking macros. 

Protocol Transfer 

People seem to have taken two sepa- 
rate paths in their use of microcom- 
puters as data communications devices. 
One type of system (generally non-CP/M) 
is used mainly for electronic mail func- 
tions and bulletin boards. Another type 
of system (usually running under CP/M) 
concentrates on file transfer protocols 
needed to exchange programs and 
databases. 

Several handshaking protocols have 
been developed to ensure the accurate 
transfer of data. The protocols in use 
include the cyclic redundancy check 
(CRC) and the Christensen protocol (cre- 
ated by Ward Christensen, one of the 
CBBS developers). Some programs, such 
as ST80-III. written by Lance Micklus. 
take the middle course — they check the 
transmitted data against the received 
echo and warn of errors. But most ter- 
minal programs ignore error detection 
and correction. 

Z-Pro seems to span both camps. It has 
the prompted file transmission common 
in terminal programs and the error detec- 
tion and correction found in the dedicat- 
ed file transfer programs. Z-Pro will also 
support the PAN electronic mail format. 
(See last month's column for a brief dis- 
cussion of PAN.) 

Z-Pro also has something completely 
new: interactive macros. Most macro 
files (including those in Z-Term) are sim- 
ply files of data that are prestored and 
transmitted out of the modem port at the 
appropriate time. The first bytes often 
cause a modem to dial a number, and the 
remaining bytes may transmit a sign-on 
or directive code, but the timing of most 

Microcomputing, December 1981 21 



systems makes it nearly impossible to 
get dialed in and signed on with one key- 
stroke. The macro is really sending blind 
unless you direct the transmissions at 
every appropriate time. 

The macros in Z-Pro are actually 
miniprograms. Once you get them set for 
your needs, you can initiate the macro 
and walk away. The system can dial the 
number, sign on to a carrier like GTE 
Telenet, request an information utility 
like The Source, sign on to the utility, 
refuse the bulletins, refuse Chat and 
check your mail while you are making 
your first cup of coffee. It can do this 
despite the irregular system response 
times that fool every other smart ter- 
minal program. 

All that power might make you think, 
"It should be easy to tie in the macro ac- 
tivation with a clock card and eliminate 
the need for the human element. The sys- 
tem could sign on during the lowest rate 
period, receive mail, dump prestored 
mail and sign-off automatically. The user 
would be cut loose from one bond of the 
time tyranny of telecommunications." 
When are you going to go the final inch, 
Bill? 

Z-Pro has a lot of other features, in- 
cluding a buffer for the printer and the 
ability to exchange data at 1200 bits per 
second (using an appropriate modem). It 
can be fully integrated with the powerful 
Apple Cat II, and can make use of that de- 
vice's Baudot/Murray code capabilities. 

Cost and Requirements 

Both Z-Term and Z-Pro require an Ap- 
ple II with the Microsoft Softcard, CP/M 
and at least 44K bytes of RAM. They can 
support various integrated modems and 
communications cards. They also get 
along fine with lowercase adapters and 
80-column display boards. They are 
available from Southwestern Data Sys- 



tems, 10159-G Mission Gorge Road, 
Santee, C A 9207 1 . Z-Term costs $99 and 
Z-Pro is $149. 

With The Utilities 

Stroke for stroke. The Source and Com- 
puServe are still giving the spectators a 
good race. CompuServe continues to im- 
prove its Consumer Information Service 
with some really useful special-interest 
groups and unique bulletin boards. The 
Source, however, has come up with yet 
another way to attract the attention of the 
crowd. 

College via Computer 

On October 5, Colorado Technical 
College began offering three college- 
credit courses on The Source. Electronic 
English, Supervision and Small Business 
Management are taught concurrently as 
classroom and telecommuting courses. 
The methods of instruction include class 
discussion, reports, computer conferenc- 
ing and a teaching method dubbed 
"electure." 

Colorado Technical College is ac- 
credited by the North Central Association 
and ABET. It offers both bachelor's and 
associate's degrees. Telecommuting stu- 
dents are accepted into the courses under 
the same admission policies as local 
students. Telecommuting students must 
be on line for at least two of the eleven 
classes for a minimum of one hour. 

The Chat mode of The Source is used to 
link the telecommuting students with 
the class and instructor in Colorado dur- 
ing these synchronous sessions. The rest 
of the assignments, discussions and lec- 
tures can be done at times convenient to 
the student by using The Source's stor- 
age capability to bring the classroom 
alive for the student. 

Each course requires the student to 
turn in written reports over The Source. 



The tuition is $210 per course, but this 
does not include your on-line charges. At 
$4.25 a connect hour (assuming no long- 
distance calls are needed to enter The 
Source), the Source usage charges will 
run between $45 and $75 per course. 
This may seem high at first, but consider 
the cost of the gas needed to commute to 
your local school over a semester and the 
freedom this method of education gives 
you in setting your own time. You may 
find these novel courses to be a bargain. 
Other course offerings will be coming 
soon. 

I should add that The Source has no tie 
with Colorado Technical College. Profes- 
sor David R. Hughes is pioneering this 
use of a new medium for formal educa- 
tion. The college might decide to use 
other electronic transmission systems 
(including direct dial) as appropriate, but 
The Source certainly provides an appro- 
priate "meeting room" for students 
learning about business and language in 
the electronic-information age. 

If you are interested, contact the Colo- 
rado Technical College placement direc- 
tor at 303-598-0200. 1 will be watching to 
see whether this use of data communica- 
tions systems grows. Who knows? I 
might be good for a guest "electure" or 
two myself. 

Tell me! 

If you intend to start the new year by 
marketing equipment or programs for 
communicating microcomputers, let me 
know. If you have any specific questions 
about communicating-microcomputer 
systems, ask me. but please include a 
stamped envelope for the reply. Send pa- 
per mail to PO Box 691, Herndon. VA 
22070. Save a tree and send electronic 
mail to TCB967 on The Source, 
70003,455 on CompuServe or to the 
AMRAD CBBS, 703-734-1 387. □ 



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22 Microcomputing, December 1981 



Reader Service for facing page ^253— 




Data communications can open up a whole new world to you and your computer. A world of the future. Now. 
A world full of information resources, time-sharing computer systems, and electronic "bulletin boards." All you 
need for admission to this world is your CP/M - based computer, a modem, and the proper software. That's where we 
come in. We have the proper software. CROSSTALK,™ our smart terminal & file transfer program for CP/M, allows 
you to call into thousands of dial-up computer systems around the world, and communicate with them. REMOTE, 
our CP/M remote console program, allows you to operate your CP/M system from a remote terminal, giving your 
computer added flexibility and usefulness. 

CROSSTALK 

• Allows your computer and modem to communicate with other computers, including other CROSSTALK systems, 
public-access "bulletin board" systems, main frame computers, subscription "Information utilities" such as THE 
SOURCE,™ and much more. 

• Simple, easy to use "plain English" command structure makes CROSSTALK easy to learn, yet provides a powerful 
tool for exchanging files, capturing data, and controlling modem parameters. 

• Concurrent printer and video allows you to print data while viewing it on the CRT. 

• Fully error-checked file transfers using 16 bit CRC protocol. Protocol transfers allow exchanging files which are 
larger than the systems memory. 

• Built in "DIR" command. 

• Data capture allows saving received data onto your disk. 

• Auto-dial, redial, and auto-answer (if supported by modem). 

Available for the following modems: Hayes 80-103a 

Hayes Smartmodem™ 

Hayes Micromodem 100™ 

PMMI Communications MM-103 

Hayes Micromodem II™ for the Apple II* 

Any RS-232 modem, including 1200 baud modems 

REMOTE 

• Allows remote use of your computer from a remote terminal location. 

• May be called as a subroutine from BASIC, PASCAL, or any other program to allow answering under program control. 

• Provides nulls if needed for printing terminals. 

• Uses less than 1 k of memory space. 

• Automatically selects proper baud rate. 

• Available for S-100 modems (Hayes and PMMI) only. 

For details, see your computer retailer, or contact us directly. 

Microstuf, Inc. *^ 253 
1900 Leland Drive, Suite 12 
Marietta, Georgia 30067 
(404) 9520267 

Smartmodem™and Micromodem'" are trademarks of Hayes Microcomputer Products, Inc. /Apple is a registered trademark of Apple Computers. Inc 
CROSSTALK is a trademark of Microstuf, Inc. /CP/M is a registered trademark of Digital Research Inc. 







DEALER INQUIRIES WELCOME. 



COMPUTER BLACKBOARD 

The Value 
Of Models 



By Walter Koetke 



Aids in 

Solving 

Problems 



Mathematical Models 

You are already familiar with many dif- 
ferent types of models— model airplanes, 
model ships, model cars, doll houses, or 
even dolls themselves; One model is usu- 
ally called "better" than another if 
it is more realistic. For example, toy 
dolls, which are intended to be models of 
real people, are made to walk, to blink 
their eyes, to have real hair, and to have 
many other properties of the people they 
represent. 

All models, however, are not just toys. 
Scientists, engineers and mathemati- 
cians try to model all aspects of space 
travel before a rocket is launched. If a 
model spacecraft is found to be unsafe 
before the actual spacecraft is built, then 
not only money and time, but human 
lives can also be saved. Political can- 
didates and the news media try to model 
the voting patterns of people so they can 
predict the winners of important elec- 
tions. The design of a new airplane, the 
results of rapid population growth, the 
durability of a new product, the 
widespread effects of building a new 
dam, and many other very complex prob- 
lems are modeled by very serious people 
with very elaborate equipment. 

With the assistance of the rapid com- 
putation speed available on modern com- 
puters, the usefulness and accuracy of 
models has increased sharply. Many 
modern models are mathematical 
models. A mathematical model for the 
design of a new airplane wing does not 
look very much like an airplane wing, but 
consists of a series of expressions and 
equations that represents the new wing. 
The model also represents the many dif- 
ferent factors such as air pressure, air 
speed, temperature and altitude that can 
affect the wing's performance. With the 
aid of the computer, a mathematical 
model can simulate the behavior of the 
new wing under many different operat- 
ing conditions. After the mathematical 
model indicates that the new wing design 

24 Microcomputing, December 1981 



is acceptable, then a more conventional 
model that looks like a wing can be con- 
structed and tested in a wind tunnel. 

In other applications mathematical 
models can simulate relationships that 
are impractical or impossible to simulate 
with physical models. The long-term ef- 
fects of several different techniques for 
treating a polluted river cannot be reli- 
ably simulated with a physical model. 
However, very realistic mathematical 
models can be constructed. First the 
mathematical models indicate the most 
effective treatment. Then the actual 
stream can be economically treated us- 
ing the technique that has already been 
proven successful in model form. 



C START J 



INITIAL VALUES 



B'lOO 



0-0 



STARTING 
BALANCE IN 
ACCOUNT. 
NUMBER OF DAYS 
INTEREST HAS 
BEEN PAID. 



COMPUTE INTEREST 
FOR ONE DAY 



I«- B«\ 



05 



365 23. 



ADO DAY'S INTEREST 
TO PRESENT BALANCE 

■ «-■♦! 



A00 I TO COUNT OF 
DAYS COMPLETED 
D*-0 ♦ I 




NO 



PRINT B, THE 
PRESENT BALANCE 



( DONE ) 



Fig. 1. Algorithm to determine the 
balance in a savings account. 



Let's examine what appears to be a 
simple but useful mathematical model. 
Suppose that while cleaning the garage, 
Dave's mother in ids a bank book in an 
old suitcase. The book shows that a 
single deposit oi one hundred dollars was 
made in a local bank on April 1, 1941. 
The book was probably then lost, since 
there are no other entries. The account 
indicates that tut Dank pays an annual 
interest rate of 5 percent, which is com- 
pounded daily and added to the account 
quarterly on January 1, April 1, July 1 
and October 1 each year. 

Dave is anxious to take the book to the 
bank to diseovti how much money the 
account now eoniains. Since today is 
April 1, 1981, exactly 40 years' worth of 
interest should be added. However, since 
today is also Sunday and he must go to 
school next week, his curiosity may not 
be satisfied beioie next Saturday. 

Fortunately, his problem can be solved 
with the help of a mathematical model 
and the computer iacilities at his school. 
The total balance of any savings account 
(started with A dollars, to which an an- 
nual interest rate of P percent is com- 
pounded T times per year for Y years) can 
be obtained using the expression: 

A , I+ WW0,Y.T 

T 

Since Dave knows the value of each 
variable: 

A = 100 dollars 

P = 5 percent 

T = 365.25 days per year 

Y = 40 years 

the expression can be used to determine 
the current balance of the old savings ac- 
count. By substituting these numerical 
values into the expression, he obtains: 

100(1+ 3Q22riO»366.25 

365.25 

which can be written as: 



100(1 + 



.05 



I4blu 



365.25 

This expression, evaluated using a 
calculator or the very short BASIC pro- 
gram: 



10 PRINT 100M1 + .05/365.25)t 14610 
20 END 

represents a balance of $738.28. The ex- 
pression A(l +(P/100)-rT)t(Y*T) is a 
mathematical model that can be used to 
determine the balance in a savings ac- 
count without using any money, without 
consulting a bank, without waiting for 
several years to elapse, and without even 
having a savings account. 

Another model for computing this 
same balance, and one that does not de- 
pend upon knowing a special expression, 
is the algorithm shown in Fig. 1. This 
algorithm is represented by the BASIC 
program: 

10 LET B= 100 

20 LETD = 

30 LET I = B*( .05/365.25) 

40 LETB = B + 1 

50 LET D = D + 1 

60 IF LK = 14610 THEN 30 

70 PRINT B 

80 END 

The balance output by a run of this pro- 
gram is $738,905. Unfortunately, Dave is 
confused because these two models do 
not yield the same balance. To make 
matters worse, his mother went to the 
bank, which computed the current bal- 
ance of this account as $738.88. Why did 
the models indicate balances of $738.28 
and $738,905, when the correct balance 
is $738.88? Since the better model is the 
more realistic one, Dave is anxious to 
learn why neither model gave the exact 
answer. His mother observed the follow- 
ing ideas that were not correctly simulat- 
ed by Dave's model. 

1. The number of days in a year is not 
365.25, but exactly 365 days except dur- 
ing leap years. During leap years there 
are exactly 366 days. This means that 
the daily interest payment should be 
B*(.05/365) or B*(.05/366) depending on 
the year. During the years 1933 through 
1973 there were ten leap years — 
1936,1940,1944 and every fourth year 
thereafter. 

2. The bank adds interest payments to 
the account four times each year. The 
balance is always rounded to the nearest 
cent when the interest is paid. The 
balance is not rounded to the nearest 
cent in either of the two models. 

A mathematical model that includes 
these two ideas would be more com- 
plicated, but would yield the correct 
balance. In fact, most banks use com- 
puters and similar mathematical models 
to compute the current balance of all ac- 
counts. Whenever a mathematical model 
is created, you must exercise extreme 
care to make the results as accurate as 
possible. If the model is not 100 percent 
accurate, the percent error of the model 
should be calculated. 

Dave's mother was also concerned 
about another question, but she wasn't 
sure how to explain the problem to him. 
After he had initially obtained two dif- 
ferent answers on his TRS-80, his mother 
asked her friend to do both computations 
on her Apple. Unfortunately, the Apple 



produced 738.80 and 738.905, respec- 
tively. When she then tried to use the 
PDP 11/70 at the local college, she was 
confidently given yet a third pair of 
answers. 738.47 and 738.905. She was 
confused as to why three different com- 
puters would calculate three different 
values for the same mathematical ex- 
pression. An explanation of this will be 
the subject of a future column. For the 
moment, however, be advised that you 
should not assign a programming prob- 
lem to students without first attempting 
to solve that problem. And you must 
never label a student's answer incorrect 
without considering the possibility of 
computational error that the student was 
not prepared to anticipate. 

Homework Assignments 

As promised last month, lets now ex- 
amine a few problems appropriate for 
student solution with computer support. 
None require s any nioie mathematical 
background than a lew months ol 
algebra. 

1. Doris is studying the population 
growth of a certain type of lly In her 
biology class. She begins her experiment 



Let's now examine 

a few problems 

appropriate for 

student solution 

with computer support. 



with ten flies, and has predicted the 
following pattern to the population 
growth: 

• Each month, every pair of flies can pro- 
duce exactly ten new pairs of flies. 

• After producing their offspring, the 
parent flies always die. 

• Twenty percent of the pairs of ilks 
born each month will die without 
reproducing. 

A. If Doris conducts her experiment lor 
the entire ten-month school year, exactly 
how many flies will be alive when she 
finishes her work? 

B. Write a program that will allow a 
user to enter the number of flies at the 
beginning of the experiment and the 
number of months that the experiment 
will last. The program should then 
calculate and display the approximate 
number of flies expected to be alive when 
the experiment concludes. 

Notice that this problem can be solved 
without any flies and without waiting ten 
months. The problem should be solved 
by creating a mathematical model that 
simulates the fly population. 

2. A program that models the 
Gregorian calendar can be both fun and 



interesting. Although the Gregorian I 
calendar is very accurate— an error of 
only one day in 3320 years— it is only 
based on a few simple facts. 

• There are 30 days during April. June, 
September and November: 28 days dur- 
ing February except in leap year when 
there are 29; and 31 days in all other 
months. 

• Leap years are those years that are 
divisible by 4 but not by luo or are divisi- 
ble by 400. 

• January 1. 1800, was a Wednesday. 

• The calendar will repeat every 40U 
years. 

Using these facts you can write pro- 
grams that: print a calendar for any given 
year: determine on which day of the week 
a particular date did or will ot c ur : oi print 
any information that can be de tern lined 
by looking at calendars. For a specific 
task, write a program that will permit a 
user to enter the month, day and year of 
any date after January 1. 1800. The pro- 
gram should then print the day of the 
week that corresponds to the given date. 
The output from a run of your program 
might appear as: 

RUN 

.' 10. 2. 19J9 represents October 2. 1939 
MONDAY 

3. Suppose you are a baseball manager 
in the unhappy situation of having an en- 
tire team with individual batting 
averages of .220. To make matters worse, 
when a player gets a hit there is only a 
one-tenth chanee that the hit is a double 
lather than a single. What is the average 
number oi runs your team will score in a 
nine inning game? Assume that a single 
will advance each runner one base while 
a double advances each runner two 
bases. 

Alter answering this question you may 
be interested in expanding your program 
>>o the nine diiterent batting averages of 
an entire team can be entered. By doing 
tins and running several simulations, 
you can discover the most effective bat- 
ting order. When properly used, com- 
puters can make positive contributions 
in some unexpected areas. What other 
Junctions of a baseball manager might a 
computer assist? 

4. Suppose you must cross a 1200 mile 
desert in your jeep. The gas tank holds 30 
gallons and you are confident of obtain- 
ing 15 miles per gallon. At your home on 
one side of the desert you can obtain all of 
the gasoline you require. What is the 
minimum number of gallons required to 
cross the desert? No, the answer is not 
that you cant go further than 450 miles, 
nor is the answer a trick. If you need help, 
consider the methods used to climb Mt. 
Everest. 

Mathematical models and simulations 
are playing an ever-increasing role in our 
lives. Providing students with the 
background and facilities for creating 
their own models should be an integral 
part of today's science and mathematics 
classes. G 

Microcomputing, December 1981 25 



MICROSCOPE 



Put on Your 
Running Shoes 



Compiled by Eric Maloney 



Nike Lab 

Uses Micros 

For Research 



Nike Goes Micro 

The treadmill rotates tirelessly as the 
runner strides on its platform, running 
hard but never moving ahead. Off to the 
side, two men sit in front of a tangle of 
machinery, looking at dials, screens and 
only occasionally at the lonely runner 
himself. One of the men turns a dial and 
the platform of the treadmill angles up- 
ward ever so slightly. The runner sud- 
denly finds himself moving backward 
and must increase his efforts to stay in 
place— at the cost of a greater expendi- 
ture of energy. 

Soon, the runner, breathing into a plas- 
tic mask connected to a flexible tube, 
begins to falter and, with a wave of his left 
hand, signals that he has had enough. 
The treadmill slows to a halt. The second 
man types a few keystrokes into an Apple 
microcomputer and reports, "In a min- 
ute we'll know your V0 2 ." 

These men, exercise physiologist Jack 



Daniels and technician Jamie Larsen, 
work for Nike Corp., one of the world's 
largest manufacturers of shoes for run- 
ners. The tests they perform on the run- 
ners who visit the Nike Reasearch and 
Development facility in Exeter, NH, are 
helping them amass data to better under- 
stand the dynamics of endurance exer- 
cise and running efficiency. To help 
in these tasks, Nike uses an Apple 
microcomputer. 

The Biomechanics Lab, under the di- 
rection of E.C. (Ned) Frederick, originally 
acquired its Apple as a backup to its Digi- 
tal Equipment Corporation PDP- 11/34 
minicomputer — the Apple can easily 
communicate with its larger brother. 
The Lab was also looking for a portable 
device. Daniels and Frederick plan to use 
the Apple in outdoor running tests 
designed to measure important physio- 
logical factors under real conditions. 
Since the computer was obtained, the 
personnel at Nike have found an increas- 
ing number of ways to use it. 




An Apple plays a key role in the Nike lab. 
26 Microcomputing, December 1981 



Running Efficiency 

The Apple's principal role at present is 
to monitor the tests of running efficiency 
performed by Daniels and Larsen. These 
tests, conducted on the treadmill, meas- 
ure efficiency by analyzing the gases ex- 
haled by the athlete while he runs. His 
exhalations are trapped by a mask on his 
face, and fed into an oxygen analyzer and 
a Beckman carbon dioxide analyzer. 
These devices are connected electroni- 
cally to an analog-to-digital converter, 
then a controller and finally to the Apple 
computer via its RS-232 interface. 

Using a program called Classical Gas. 
the Apple calculates the ratio of oxygen 
to carbon dioxide in the runner's exhala- 
tion and compares these figures to the 
quantities of these gases in the free air. It 
then calculates how much oxygen the 
runner is using. Its calculations are 
displayed in milliliters of oxygen per 
kilogram of body weight per minute. 

When a runner is forced to cross over 
from aerobic (with oxygen) to anaerobic 
(in the absence of oxygen) modes of burn- 
ing energy, increasing amounts of ox- 
ygen do not produce greater energy. It is 
at this point that the runner reaches his 
maximal oxygen uptake, or V0 2 max. 
For an endurance athlete like a runner, 
this is his highest level of efficiency. 

The Classical Gas program, written in 
BASIC by Jamie Larsen, is just one of 
several that the Nike Lab has produced. 
Another program, called Fat Factor, cal- 
culates from height and weight a relative 
measure of an athlete's ideal weight 
range. IMP is a statistical model that sim- 
ulates the effect that weight, height and 
running speed have on impact forces. 
Race Organization is a program under 
development to help score cross-country 
races and print out results. Impact Li- 
brary is a data file on the variety of 
materials used in Nike shoes, storing in- 
formation on rebound time, compaction 
characteristics, energy loss and other 
factors. 

All work makes for dull guys so the 

boys in the lab have come up with Race 



Invaders, a game for athletes (still under 
wraps in a dark corner of the lab). 

Undoubtedly, however, the lab's most 
famous program is its Performance 
Predictor. This program estimates from 
previous race times a time for any other 
distance. Nike used the program at the 
198 1 Boston and New York marathons to 
predict the times of hundreds of runners. 
In Boston, the program predicted winner 
Toshihiko Seko's time within 20 sec- 
onds. For most other runners in the race, 
predictions were within two minutes, 
even for finishers in the four-hour range. 
Many runners wrote to Nike after the 
event to report their time—and many 
apologized for not finishing in the time 
predicted! 

Manufacturing and the Apple 

The Nike Lab has passed the word to 
the rest of the company that a versatile 
microcomputer is a valuable tool. The 
company is now developing programs to 
analyze the data collected in its wear- 
testing project. This project is designed 
to help Nike evaluate the comfort and 
wearability of its new prototype shoes, 
using over 2000 volunteer runners 
around the country. The research and 
development facility plans to use an Ap- 
ple to track the progress of its prototypes 
through the manufacturing process, in- 
cluding keeping track of inventory. The 
marketing division feeds data from sur- 
veys of preferred colors, customer surveys 
and biomechanical questionnaire results 
to Exeter and the Apple is used to analyze 
and organize the statistics that result. 

All this information guzzling goes into 
the production of shoes that can theo- 
retically improve performance. Nike now 
offers 35 different models of running 
shoes, many designed for specific classes 
of runners. 

Even though the search for new knowl- 
edge about the physiology of running 
continues, Ned Frederick cautions: "We 
are at about the same stage that the 
American auto industry was in the early 
1950s. We're just beginning to perceive 
just how much we don't yet know." 

With an Apple at its core, the search 
goes on. 

G. Michael Vose 
Microcomputing staff 



English Computing Show 
Draws 16,000 

The rush to personal computing is on 
in England, as shown by a turnout of 
16,440 persons for the fourth annual Per- 
sonal Computer World Show, Sept. 
10-12 in the Cunard Hotel, London. 

Compare that kind of response with the 
30,000 who attended the seventh Com- 
puter Faire last April in San Francisco, 
the heart of the world computer com- 
munity, and you get some idea of just 



how interested the British have become 
in personal computing. 
Three key factors are at work: 

• The availability of cheap, useful 
machines such as the Sinclair ZX-80 and 
ZX-81 and the Acorn Atom, all of which 
offer true (if limited) computing for less 
than $300. 

• The British Broadcasting Company's 
upcoming computer literacy series, com- 
plete with tutorials based on a special 
BBC Microcomputer, which was on dis- 
play at the show. 

• The Prestel home television/computer 
system, which, while still beyond the 
economics of most English families, has 
created large awareness and intense in- 
terest in individual interaction with per- 
sonal computers. 

The organizers of the PCW show, spon- 
sored by England's largest computing 
magazine, had given much attention to 
organization, but even they didn't expect 
the turnout that saw a quarter-mile long 
line awaiting admission the first day. The 



No one expected 
the turnout that 

saw a quarter-mile 

long line waiting 

the first day. 



show occupied two exhibition floors of 
the Cunard — with recreational exhibitors 
on the lower floor and business hardware 
and software on the upper level. 

Represented among the almost 100 ex- 
hibitors were user groups, hardware 
manufacturers, software publishers, 
magazines and even an instant copying 
stand, kept busy churning out photo re- 
productions of manuals purchased by 
one visitor who just wanted the extra 
copies for "backup." 

Among the busiest stands was the Tan- 
dy booth, which dominated the upper 
level, with its full range of demo TRS-80s. 
In an England sorely pressed by a soft 
economy and high inflation rates, the 
Tandy machine may be the top of the 
line— along with Commodore ("Don't 
call it PET. We've outgrown that 
image!") and Apple. 

Clive Sinclair, who stirred things up 
last year with his ZX-80 (50,000 units 
sold at $200 each), was back with the 
ZX-81. Priced even lower than the first 
generation, at about $100 for a kit ver- 
sion or $150 assembled, the ZX-81 uses 
only four chips, has an 8K BASIC 
ROM and is expandable with 16K plug-in 
RAM pack. 

Another low-end piece of hardware on 
display was the Acorn Atom, available in 
kit for about $200, and assembled for 



about $270. The bare-bones Atom, using 
a 6502 CPU and offering a 16 by 32 video 
diplay, features 8K of ROM and 2K of 
RAM. It has its own peculiar AtomBasic, 
which does not allow READ. . DATA 
operations, which offers two bewildering 
PRINT statements, and which precedes 
string handling operations with the $. 
The Atom was designed to be expanded, 
and offers such upgrades as IK RAM sets 
at $15 each, a 4K floating point ROM at 
$35, printer driver at $25 and color en- 
coder and buffer at $36. 

The Atom was selected by BBC as the 
mode for its Microcomputer, much to the 
chagrin of Sinclair, who grumped at the 
time: "What the BBC is doing, it is do- 
ing badly." 

The BBC micro, slightly more expen- 
sive than the Atom, seems to be a lot of 
machine. It has a 73-key QWERTY full- 
travel keyboard and 16K of ROM, uses 
Microsoft BASIC, has 32x40 or 25x40 
video output and supports color graphics 
up to 320 by 256 on a standard European 
PAL system television receiver. In addi- 
tion, the Model B, the top of the line, of- 
fers 32K of RAM, 640 by 256 color graph- 
ics, a Centronics-type parallel printer 
port, a RS-423 serial interface compatible 
with the RS-232C and the ability to net- 
work with up to 255 other users. 

Another machine unfamiliar to the 
States worth mentioning is the DAI per- 
sonal computer, from Data Applications 
International of Brussels. It was born 
under a development agreement with TI. 
TI then walked away from it and Data In- 
ternational, whose main business is in- 
dustrial controls, was left wondering 
what to do with a high-performance color 
and sound generating machine that 
could be sold for around $1100. They 
figured it out. 

The machine is based on the 8080A 
microprocessor and is available with up 
to 48K of RAM, plus 24K of bank switched 
ROM that contains the resident software 
and a BASIC interpreter that emulates 
Microsoft, monitor and other housekeep- 
ing functions. Housed in an integral full- 
travel keyboard, the machine features 
16-color, 256 by 336 high-resolution 
graphics, stereographic sound genera- 
tion, and plugs for everything except 
your electric shaver. The interfaces 
include game paddle sockets, dual cas- 
sette input, and RS-232C and DCEbus 
interfaces. 

If there was a noticeable shortcoming 
in the show, and perhaps in British per- 
sonal computing as a whole, it was in the 
area of software. One dealer explained: 
"It seems that we have to import it all, 
either from the States or the Continent, 
and then translate it. You Yanks don't 
even know how to spell programme." 

As might be expected, most of the soft- 
ware on display was aimed at the small 
machines mentioned above. The busi- 
ness software was largely Apple and Tan- 
dy, with only a few offerings in CP/M and 

Microcomputing, December 1981 27 



other larger system formats 

One of the major si ich offerings was Sil- 
icon OtTiee. billed as a eomplete office 
management system— word processing, 
payroll, financial, etc.— one package 
The problem, according to a competitor, 
is that it is "designed for a machine that 
doesn't yet exist (the Commodore 9602) 

The second major piece of software, 
which drew large crowds to its Tandy- 
machine demonstration area, was The 
Last One, a code-generator first intro- 
duced in San Francisco in April and 
which has been supported bv what is 
believed to be a million-dollar advertising 
budget. Michael Falter. vice-president of 
marketing for DJ "AT Systems, Inc.. the 
publisher, would not denv nor confirm 
the published report that about $9 mil- 
lion in orders have been taken for the pro- 
gram, which was expected to be shipped 
in October. 

The user groups and club displavs 
were constantly active signing new 
members. The magazine publisher 
booths sold briskly. (Tip to show-goers: 
Wait till late afternoon of the last day. 
You can get two, three or four for the 
price of one. No publisher wants to carry 
all those back issues home again.) 

The second annual Microcomputer 
Chess Championship was won by a 
homebrew program that brushed aside 
all five of its opponents in the 12-entry 



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field, whieh ineluded sueh popular and 
well-known systems as Gambiet 81. 
Philidor and Chess Champion Mark V. 

Riehard Lang, who wrote Cyrus in 
about six months of spare time, is a 
26-year-old researeh programmer for the 
English natural gas utility. His winning 
program, written in Z-80 assembler lan- 
guage, oecupies just over 7K of memory 
and ineludes an opening book table of 
1.25K whieh "I took straight out of the 
Penguin paperbaek of chess openings." 

According to Michael Stean, an inter- 
national master, the program is par- 
tirularly exciting in its ability to mount 
powerful coordinated attacks using nu- 
merous pieces, without the emphasis on 
the queen shown by many programs. Cy- 
rus's end-play capabilities are a matter of 
conjecture, however; Lang noted, "He 
usually doesn't get that far before win- 
ning." All five games in the tournament 
were won in the middle game. 

When last seen, Lang was fending off 
potential marketers, and saying. Ver- 
sion 2, which is almost finished, will be 
considerably stronger." 

As the show wound down on a glorious 
fall Saturday afternoon, David Tebbutt, 
former editor of PCW and now President 
of Caxton Software. Ltd., and the man 
who spurred these first four PCW shows, 
said: "It looks like they'll be seeking 
much bigger space next year." 



And who knows what Sinclair will be 
offering then? 

By Edgar F. Coudal 
Special to Microcomputing 




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^254 



RFI Regs Defeat 
Compucolor II 

The Federal Comrnunieations Com- 
mission's new radio frequency interfer- 
ence regulations have claimed at least 
one victim in the microcomputer world. 

Intelligent Systems Corp. has decided 
to pull its Compucolor II from the U.S. 
market. The reason: changes required to 
meet the FCC's class B standards would 
cost too much money. 

'The Compucolor II was not especially 
profitahle for us to begin with," says 
Susan Sheridan, ISC's manager of mar- 
keting communications. "When the FCC 
came up with its ruling, we looked into 
what changes would be required, and 
decided that it would cost too much in 
money and resources." 

Sheridan says that the necessary 
changes were probably no more involved 
than those made by Apple or other com- 
panies. But, she adds. Apple's Apple II 
was making too much money to be pulled 
from the market. The Compucolor II has 
not brought in enough revenue to make 
the investment worthwhile. 

Much of the problem lay with a lack of 
manpower, Sheridan says. 

"For example, we would have had to 
change the analog board," she says. "At 
the time, we were designing a new analog 
board for our other computers, and it 
would have meant pulling one of our en- 
gineers from that project." 

Also, says Sheridan, ISC has a comput- 
er in its Intecolor series which is in a price 
range to be used as a home computer. 

The Compucolor II is based on the 
8080A microprocessor, and includes 8K, 
16K or 32K byte models. Its base price is 
$1895-82495, and is targeted for the 
home and school market. 

Although the micro will no longer be 
sold in the U.S., the company has prom- 
ised to maintain customer support. It will 
still publish Coloreue, a bimonthly 
magazine for Compucolor and Intecolor 
owners, and provide parts and repair. 

ISC will continue to market the Com- 
pucolor II in Europe. 

The FCC regulations require that Class 
B computing devices — those intended for 
home use— meet stringent regulations to 
control potential interference with other 
electronic and communications devices. 
The major micro manufacturers— in- 
cluding Apple, Radio Shack. Ohio Scien- 
tific, Commodore and Atari— have re- 
ceived certification for their micros. 

A complete story on the new regula- 
tions appeared in Microcomputing's 
April issue ("FCC Takes Aim Against RFI 
Polluters." p. 30). n 



28 Microcomputing, December 1981 





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LETTERS TO THE EDITOR 



You Have Won A New 
Ferrari! 

In your Sept. issue you had a fascinat- 
ing piece on instant mail (Publisher's 
Remarks, p.6). The article touches on the 
fly in the ointment of instant mail— the 
junk mail problem. Can you imagine the 
benefit to the direct mail advertiser of a 
message that must be at least partially 
scanned? Currently you can pretty well 
tell if a letter is junk mail and trash it 
unread or at least defer it. With the use of 
electronic mail you will need to read at 
least part of it to determine content, 
and at that the probability of sales 
multiplies. 

Please do not interpret this as nit- 
picking. It's merely that I can see logging 
on my home terminal and immediately 
getting a raft of messages— most of them 
to the effect that I have won a Ferrari, a 

ssna, a new home or a solid walnut 
toothpick if I will visit some dumb devel- 
opment. Since buried in this mass of mail 
may be a letter informing me the city has 
tripled my property taxes, or I have in- 
herited controlling interest in a major oil 
company, none of the mail can be ig- 
nored, so I will be stuck with reading at 
least some part of each piece. 

The economics for the personal or busi- 
ness mailer would have the advantage of 
finer demographic targeting with area- 
code-prefix coding. They would be able to 
buy a couple of WATS lines, program 
their computers to dial the selected area 
and prefix and deposit their message in 
every mailbox for that prefix. With the 
development of standard protocols and 
low-cost fax equipment, the transmis- 
sion of pictures, graphs and other 
brochure equivalents, perhaps even in 
color, could go along with the mail. All 
designed to capture the attention of the 
reader. 

The avoidance of this corruption of 
what is really a potentially outstanding 
tool will require a great deal of thought. 
Such techniques as capturing and pass- 
ing through the originating number with 
the receiver being able to program his 
site to ignore WATS originated entries 
are possible but would compromise some 
of the system's value. I would hold out no 
hope of governmental regulation since 
the direct mail people have such a strong 
and well-financed lobby. 

Another possible control would be for 
the subject to provide all the possible 
mailers with a priority number or code 
controlled by him. The program at the 
terminal would scan for such codes and 
direct the mail to the appropriate bucket, 
each of which could be scanned at will. 

30 Microcomputing, December 1981 



Those pieces not having a priority would 
be put in a file 13 equivalent that would 
be looked at when nothing else is going 
on (or dumped). Obviously creditors 
would not be given one of the high priori- 
ty codes. 

As an old-timer (nearly 25 years) in the 
use of computers, I long ago learned that 
very little comes up as clean and unclut- 
tered as initially envisioned. However, as 
an old-timer I have long since learned not 
to put any limit on what can be done. 
Therefore I am in full accord with you 
that direct mail will be accomplished and 
indeed look forward to seeing how it is 
done. 

Richard J. Kelley 
Sapulpa, OK 



Electronic Mailbox Now 

Mr. Green's plea for an electronic mail- 
box in September's "Publisher's Re- 
marks" has already been answered, at 
least in part. British Telecom has even 
implemented the encoded dictionary 
that he envisioned. 

For background information: Prestel 
adapters cost about $260 and up. TVs 
with adapters are available from rental 
companies. A local telephone call is 
about 7 cents for two minutes at peak 
time, falling to seven cents for 12 
minutes from 6 pm to 8 am. 

R. Larkin 
London, England 



Speed Up FILEMAP 

I was very excited about the FILEMAP 
program found in your September 1980 
issue ("FILEMAP," by Douglas L. Jones, 
p. 166) because many of my programs are 
in excess of 17K and there are hassles in- 
volved in hunting down variables when- 
ever extensive changes must be made. 

Therefore, I entered this program onto 
my system for a try. I found somewhat to 
my disappointment that the program is 
slow. 

After close examination of the pro- 
gram, it appeared subroutine 1 100- 1 120 
could be speeded up. The main problem 
as I saw it was the RESTORE usage and 
the serial search for the BASIC command 
string. From the typical list of BASIC 
commands one can find a reasonable al- 
phabetical distribution of them. 

The task was easy. Read in all the 
BASIC commands into an array. Set up a 
second array containing the alphabetical 
pointers (see lines 185-195 in Listing 1). 

The second half of the problem was 
adapting this approach to subroutine 
1100-1120. This subroutine improve- 
ment simply checked the first letter of 
the string and then would serially search 
BASIC commands beginning with that 
letter. For example, if the first letter of the 
string SS$ was O then the subroutine 
would compare OCT$. ON, OPEN, OR 
and OUT thus skipping ABS. AND, . . . 
etc. until it got to OCT$. Obviously, this 

(continued on p. 211) 



1105 



185 DATA1, 7, 7, 21, 33, 43, 50, 53, 54, 60, 

60,61,74,81,86,91,96,96,105,116, 
121,125,129,129,129,129,129 
190 CLEAR5000:DEFINTA-F:BS=129:CX$=CHR$ (12) :DIMCH$ (BS) ,CC(27) 
195 F0RJ=1T0BS:READCH$ (J) :NEXT: F0RJ=1T027 :READCC (J) :NEXT 
1100 FL=0:N=ASC(S$) :IFN<650RN>91THEN1115 ELSE N=N-64 

F0RNN=CC (N ) T0CC (N+l ) -1 : 

IFLEFT$ (S$,LEN(CH$ (NN) ) ) =CH$ (NN) THEN 

FL=LEN(CH$(NN)) :T=FL:NN=CC (N+l ) -1 

NEXT 

IFFLO0THENS$=RIGHT$ (S$ ,LEN (S$) -T) :S2$ = "" 

S=LEN (S$) : RETURN 

•SPOOL 

WIDTH80 

INPUT"D0 YOU WANT (C)RT OR (L) INE PRINTER OUTPUT" ;F3$ 

IFF3$O"C"ANDF3$O"L"THEN1320 

OPEN"I",1,F2$,0 

IFEOF(1)THEN1390 

LINEINPUT#1,A$ 

IFF3$="C"THENPRINTA$ ELSE LPRINTA$ 

GOTO1350 

CLOSE 

END 



1110 
1115 
1120 
1300 
1310 
1320 
1330 
1340 
1350 
1360 
1370 
1380 
1390 
1400 



Listing 1. 



ANNOUNCING A INVOLUTION 
IN TH€ COST OF PROFESSIONAL SOFTWARE 




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RLL SVST€MS is able to provide you VisRccount at this incredible 
low price because it runs on so many different machines. Through 
volume sales we are able to substantially reduce our prices. 

OUR GUARANTY — Buy both our software and that of our 
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t Microcomputers for Business Applications. 1979 



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operation 

Available for TRS-80 I, II & III, Apple* and most others. 
*The Apple version requires the Microsoft Z80 softcord. 
CSCA hos CBASIC2, CP/M ond Microsoft Z80 softcord in stock. 





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Microcomputing, December 1981 31 



For home, business or industrial applications, this single-board do-it-yourself system 

has broad appeal due to its simplicity and low cost. 



Everyman's Computer System 



By John McKown and Steve Sarns 




The 8073 single-board computer system. 
32 Microcomputing, December 1981 



If you haven't yet taken the plunge into microproces- 
sors, here is a system that can make a beginner suc- 
cessful. You can assemble the computer and be program- 
ming it on the same day. If you're considering an intelli- 
gent home-security or energy-management system, you 
can build a low-cost system that won't tie up your not-so- 
low-cost personal computer. Changes to software can be 
made in one-tenth the time of most single-board com- 
puters, because this one talks an English-like BASIC 
language. 

The system is designed to overcome the problems 
we've met in dealing with a variety of controller prod- 
ucts. The number of computer applications in our com- 
pany has skyrocketed over the last few years. Our non- 
product uses include controlling production equipment, 
running lab experiments, automatic printed circuit (PC) 
board testing, data logging and assisting test techs with 
tedious calibrations. 

Usually, we've contracted with outside consultants to 
design and install systems. We now have a hodgepodge 
of custom designs with half a dozen different micropro- 
cessors. The documentation has been cryptic or worse, 
forcing us to rely on the designers for servicing. Since 
few of our people can program even one microprocessor 
in machine language, the biggest headache has been 
making software changes. Even so, it couldn't be done on 
the production floor where real-time tweaking is a must. 



John McKown and Steve Sarns are engineers at Cobe Laboratories Inc 
1201 Oak St., Lakewood, CO 80215. 



Once again, we had to rely on the outside organizations 
to make even minor changes. 

What we needed was a universal microprocessor sys- 
tem that was sufficiently simple so both our engineers 
and technicians could handle the hardware and soft- 
ware. Yet, it had to be powerful enough for most of our 
applications. Since we owned a lot of examples of what 
we didn't want, it wasn't difficult to develop the follow- 
ing criteria: 

•Circuitry had to be readily understood by a wide range 
of personnel. 

• It had to be programmable by nonprogrammers. 

•It had to be field-programmable with nonvolatile 
memory. 

•It needed a simple, inexpensive power supply. 

• It had to be plug-replaceable, easy to package and 
serviceable. 

•It needed sufficient I/O for most applications. 
•It had to be easily expandable. 

Since the system would be operated by personnel with 
little or no microprocessor experience, a high-level lan- 
guage was mandatory. We decided that a small BASIC in- 
terpreter would be ideal. To possibly simplify the cir- 
cuitry, we also looked at several central-processor unit 
(CPU) chips with integral BASIC interpreters. Unfortu- 
nately, many Tiny BASICs have inconsistent syntax and 
lack meaningful error messages. However, we found an 
enhanced version that looked very good. 

The design of a system was not yet a company project, 
so we got together nights and weekends to work out the 
hardware configuration. After trying several schemes, 
we settled on what appeared to be the least complicated 



READ CYCLE 



ADDRESS IMPEDANCE 



X 



NRDS IMPEDANCE 



VALID ADDRESS 



/l\! 



\ 



250 



DATA INPUT 



Hl-Z 



/ 



1000 



250 



IGH 
MPEDANCE 



Hl-Z 



600 



X VALID \/~ ui 
DATA /^ HI-. 



^ACCESS* 



WRITE CYCLE 



ADDRESS 



NWDS 



Hl-Z 



X 



Hl-Z 



VALID ADDRESS 



X 



500 



\ 



/ 



750 



250 



Hl-Z 



Hl-Z 



DATA OUTPUT 



Hl-Z 



A 



VALID DATA 



250 



A 



Hl-Z 



250 



Fig. 1. The 8073 bus external memory read/write cycle timing. All times 
are given in nanoseconds and the system clock runs at 4 MHz. 



version. The circuit can be wire-wrapped on a 4.5 by 4.5 
inch PC card, but we used a standard 4.5 by 6.5 inch card 
so that some breadboard space would be left. Two cards 
were made and run through their paces independently. 
We then wrote a set of utilities that would make the card 
a "tiny" development system. 

Of the several CPUs with resident BASIC interpreters, 
the National Semiconductor INS8073 is by far the easiest 
to use. It's hard to imagine a bus and control structure 
more straightforward than National's MICROBUS. There 
are no multiplexed address and data lines and no tricky 
timing requirements, and it readily interfaces with all the 
common peripheral chips. NSC Tiny BASIC was devel- 
oped specifically for control applications and has been 
used for several years with SC/MP and 8080 processors. 

(This interpreter was originally called NIBL. All refer- 
ences to BASIC in the remainder of this article will be 
NSC Tiny BASIC.) 

The Microprocessor 

This microprocessor supports a classic eight-bit bidi- 
rectional data bus and a 16-bit wide address bus. Three 
active low I/O strobes are provided. The Read (NRDS) 
strobe transfers data from the data bus into an internal 
register. The Write (NWDS) strobe occurs when the data 
put on the bus is valid. Pulling the Hold (NHOLD) low 
locks the information on the data and address buses until 
released. This feature allows interfacing with slow pe- 
ripheral devices. The timing diagram is shown in Fig. 1. 

The microprocessor alone supports minimal I/O in the 
form of two sense inputs and three flag outputs. The 
sense inputs can generate interrupts (if enabled) and the 
flag outputs are latched. (In our system one flag and 
sense line are dedicated to the RS-232 port.) An internal 
oscillator will accommodate either a crystal or resistance- 
capacitance network. It is possible to construct a working 
system with only three devices— the microprocessor, a 
programmable random-access memory (RAM) chip and 
an erasable-programmable read-only memory (EPROM) 
chip containing the user program. The block diagram 
(Fig. 2) shows the interconnections for this system. 

Upon power-up or reset the interpreter performs the 
following tasks: 

•The size of RAM is determined. 
•RAM is nondestructively tested. 
•Variables and stacks are initialized. 
•The data rate is established. 

•A check for a program in ROM at 8000 (hexadecimal) is 
made. If one is present, program execution begins. Oth- 
erwise, the command mode is entered and the inter- 
preter waits for user input. 

Programs are entered directly into RAM via the RS-232 
port. All characters are stored in memory as ASCII val- 
ues, and thus no tedious code conversion is necessary 
while examining memory during debugging. 

The Language 

A high-level language will be recognized as a boon to 
anyone who has fought through the hand assembly of ob- 
ject code or purchased a costly development system. One 
of the prices paid in using a high-level language is that of 
speed. Fortunately, most control applications do not re- 
quire the fast execution speed of machine language. 
However, should the need arise, the LINK command will 
jump from BASIC to an object-code subroutine and re- 

Microcomputing, December 1981 33 



turn. (The interpreter comes in handy when debugging 
machine-language programs.) 

Another possible limitation of this BASIC is that of in- 
teger math. The two-byte format limits the integer-value 
range to ±32,767. In most instances this does not repre- 
sent a serious constraint. By carefully scaling the data, 
the loss of resolution can be minimized; indeed, through 
more advanced programming, the problem may vanish. 

The common BASIC statements supported include: 
•NEW— sets the end of program pointer equal to the be- 
ginning address effectively erasing any program resident 
in RAM and signalling new program entry. 

• RUN— runs the current program. 

•CONT— continues execution at the point of suspension. 

• LIST <expression>— lists the current program starting 
at line number (expression); default value is the first line 
number. 

•REM (Remark)— skipped over during execution. 
•CLEAR— initializes all variables and stacks; done auto- 
matically when a program is run. 
•LET— optional. 

• PRINT <expression>— prints value of <expression>. 
(Multiple outputs are separated by a comma. An ending 
semicolon suppresses the carriage return.) 

• IF/THEN-THEN is optional. 

• FOR/NEXT. . .STEP-STEP is optional. 

• DO/UNTIL. 

•GOTO <expression>— expression can be a number or 

variable. 

•GOSUB <expression> / RETURN— expression same as 

GOTO. 

• INPUT— inputs can be a number or a string. 

• DELAY <expression>— delays up to 1040 ms in steps 

of 1 ms. 

•LINK <expression>— executes machine-language rou- 
tine beginning at memory location (expression). 
•TOP— returns the next available RAM address. 

• MOD <a,b>— returns the remainder of a/b. 

• RND <a,b>— returns a random number between a and 
b inclusively. 

In addition to these standard statements NSC Tiny BA- 
SIC has the following enhancements. 
•ON <expression>— causes vectored interrupts from 
the sense inputs— the statement ON 2,200 causes a jump 
to line 200 when sense B (pin 39) goes low. 
•NEW <address>— initializes pointer to a BASIC pro- 
gram without destroying any other program; thus, sever- 
al different programs may reside in memory (RAM and/ 
or EPROM) at once. 

• STAT— allows examination and modification of the 
status register. 

•@<expression>— a shorthand version of PEEK and 
POKE. 

@2000 = 67— puts 67 at address 2000. 
A = @1200— gives variable A the value at address 1200. 
Let @3000 = @4000— copies contents of address 3000 in- 
to address 4000. 

•INC <X>, DEC <X>— these are used in multiprocess- 
ing applications (see National's literature). 

Four arithmetic, six relational and three logical opera- 
tors are recognized: 

• + , - , * , / add, subtract, multiply and divide 

•<, =<, > = , > less than, less than or equal to, greater than or 

equal to, and greater than 
•< >, = not equal to, equal to 

•AND, OR, NOT logical and, or, not 

34 Microcomputing, December 1981 



The capacity for string handling enhances the versatili- 
ty of the interpreter. Strings are stored in ASCII starting 
at the address contained in the variable named. The 
statement A = 9000 tells the interpreter to store $A in 
memory beginning at location 9000. Thus: 

>A = 9000 : $A = "NSC TINY BASIC" : PRINT A,$A 

will produce 9000 NSC TINY BASIC. A string move 
statement is supported, allowing very fast reading from 
or writing to peripheral devices. 

The error codes of the 8073 are a substantial improve- 
ment over the "HOW" and "WHAT" of the early inter- 
preters. (See Fig. 3.) 

The Hardware 

The circuit was reduced to simplest form without com- 
promising function. We set the size and capabilities of 
the system to match most of the applications we had 
seen. More than 150 lines of BASIC text can be stored in 
4K bytes of EPROM. The 4K of available RAM might be 
used for program development while only 2K might be 
used for an operating system. Even the slowest EPROM 
and RAM chips have more than adequate timing mar- 
gins. (The Toshiba 2016, Hitachi 6116, T.I. 4016, Mostek 
4802 and others all work well.) 

The system has the following features: 
•Up to 4K bytes of RAM in 2K increments. 
•Up to 4K of EPROM in 2K increments. 

• Up to 8K of external RAM and/or EPROM. 
•Addresses up to 2000 peripheral devices. 
•A resident EPROM programmer. 

• + 5 V operation (EPROM programmer requires +25 V). 
•27 programmable I/O ports. 

•A peripheral device select line. 

•Serial I/O port- 110, 300, 1200 and 4800 bits per sec- 
ond (bps). 

The design of a microprocessor hardware system usu- 
ally begins with the assignment of a memory location to 
each of the various components of the system (see Fig. 4). 
This is known as memory mapping. The interpreter ex- 
pects to find data rate information at memory address 
FD00 (hexadecimal) and the auto-run EPROM at 8000, 
and it begins the RAM search at 1000. The second RAM 
must then be at 1800 while the second EPROM must be 



INS8073 



PROGRAM 
ROM/EPROM 



USER I/O 



SA/INTA ADDRESS 



SB/INTB 

Fl 

F2 

F3 



DATA 



NRDS 



NWDS 




ADDRESS 

DATA 

ENABLE 



RAM 

(256 BYTES 
MINIMUM) 



ADDRESS 
DATA 

READ 
WRITE 



Fig. 2. Block diagram of the minimum ROM/EPROM-based system. 



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Wayne Green Books 




A B® 







A COURSE 
IN DIGITAL 
ELECTRONICS 

where you 
build your 
own cornputerf 

n mcmtrnm 




*TRS-80 is a trademark of 

Radio Shack Division of Tandy Corp. 



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Microcomputing, December 1981 35 



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at 8800 for continuous memory. The internal BASIC in- 
terpreter is located at 0000, and the internal RAM is 
mapped at FFCO. 

These addresses set the decoding scheme. The remain- 
ing decoder outputs map the programmable interface at 
0A00 and the peripheral function select at 9800 (2000 ad- 
dresses). The 4000-7FFF block of code is an "image" of 
the C000-FFBF data rate address and cannot be used. 
This leaves 2000-3FFF free for external decoding, if de- 
sired (8000 addresses). 

Circuit Description 

The 8073 requires few external components. The self- 
contained crystal oscillator is buffered to drive four low- 
power Schottky transistor-transistor logic (LSTTL) loads. 
While the oscillator will operate over a range of 100 kHz 
to 4 MHz, the 4 MHz used in this system is necessary for 
accurate data rates. The data and address lines will drive 
four LSTTL loads. 

The RS-232 input circuit operates over a ± 3 V to + 12 V 
range. Ql acts as a threshold detector and inverter. The 
output stage (Q2) swings from about -4.5 V to +5 V, 
which exceeds the minimum RS-232 specs. The - 5 V for 
the output stage is supplied by the voltage converter, 
Ull. R3 and C7 form a power-up reset for the processor. 
This line is buffered and inverted for the 8255 and exter- 
nal devices. 

Since the pin-outs of the 2K by eight-bit RAMs and 
EPROMs are the same, the devices are interchangeable 
in the RUN mode. If your operating system requires only 
one RAM chip and you want to save a little money, a IK 
by eight-bit RAM like the 4118 could be used for Ul. 
(Caution: You can't use a IK RAM while developing pro- 
grams because the interpreter expects 2K.) 

The data rate is set by tying U9 to P12 and U9 to P14 
high or low. The processor wait or hold line (NHOLD) is 
activated either by the EPROM programmer or an exter- 
nal input (active low) through U10. (See Fig. 5.) 

The 8225, U5, programmable peripheral interface chip 
has 24 I/O lines that can be individually software config- 
ured as either an input or output so that no external hard- 
ware is needed. The chip has three operating modes, but 
the description is too detailed to discuss in this article. 
We will briefly cover mode 0, the most common, and 
suggest that those who are interested in the remaining 
modes consult the data sheet. 

The device is divided into three ports: (A) PA0 to PA7, 



Error code 


Explanation 


1 


Out of memory 


2 


Statement used improperly 


3 


Unexpected character (after legal statement) 


4 


Syntax error 


5 


Value (format) error 


6 


Ending quote missing from string 


7 


GO target line does not exist 


8 


RETURN without previous GOSUB 


9 


Expression, FOR-NEXT, DO-UNTIL or GOSUB 




nested too deeply 


10 


NEXT without previous matching FOR 


11 


UNTIL without previous DO 


12 


Division by zero 




Fig. 3. The 8073 error codes. 



36 Microcomputing, December 1981 



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Microcomputing, December 1981 37 



(B) PBO to PB7 and (C) PCO to PC7. The chip select line 
(U5 to P6) is mapped at 0A00 (hexadecimal) so that port A 
is addressed at 0A00, port B at 0A01 and port C at 0A02. 
An internal control register is mapped at 0A03. The con- 
trol word determines the I/O configuration. For example, 
the control word 10 (hexadecimal) makes all lines inputs 
and the control word 9B makes them all outputs. 

> @ #0A03 = #10 REM MAKE THEM ALL INPUTS 

> @ #0A03 = #9B REM MAKE THEM ALL OUTPUTS 

See the 8255 data sheet for the other combinations. 
Drive requirements in excess of about one TTL load will 
require external buffers. On power-up the 8255 initializes 
into the all-input mode. 

The EPROM programmer is read at 8000 (hexadecimal) 
and written to at 9000. When you power-up or type NEW 
#8000, the interpreter determines whether that location 



is RAM or ROM by saving the information at 8000 and 
trying to write a test number into 8000. If it is successful, 
it restores the previous byte and treats that location as 
RAM. If not, it concludes that ROM is at 8000. If you 
have your utility chip in that socket and your +25 V pro- 
gramming supply is on, it will write over the first byte 
rendering your utility chip useless. Thus, placing the pro- 
grammer at 9000 minimizes this type of error. 

When writing to 9000 through 97FF with the + 25 V 
programming supply connected, data will be pro- 
grammmed into U4. The decoded address (U8 to P9) and 
the write (NWDS) are applied to pins 2 and 3 of U2. The 
output goes high triggering the 50 ms one-shot, U7. The 
output (U7 to P6) drives the NHOLD line (U6 to P5) low 
via U10. This locks both the address and data buses in 
their present state until the one-shot output goes low. 



OPR"SYS-lA *OCTAGON SYSTEMS CORP* (C) 8/81" 

1S=S)#FFD9*256+#E8: T=S+20: U=S)#FFD5*256: *S=" " : PR" M 5 PR "Select " 

2PR*S:PR"<1> MOVE BASIC PROGRAM" 

3PR"<2> COPY MEMORY" 

4PR"<3> HEX DUMP" 

5PR"<4> DEC/HEX CONVERT" 

6PR"<5> LLIST SERIAL" 

7INPUTI:PR"":GQT0I*10*<I>0) *<I<6) 

8Y=5HJ + I) : IF(Y=127)0R<Y>57)0R<Y<49)X=0 

9RETURN 

10PR*(U+#77> : PR " SOURCE " : G0SUB80: G0SUB81 : INPUT J: IFJ=OGOT01 

1 1 J=J-#10FF* ( J = l ) -#7FFE* < J=2) : V=#l 100: W=#8000: X- #9000 1 Z=#9800 

12IF(J<V)0R< <J>S)AND<J<W) ) OR < J >=X ) PR"*NO SOURCE" : GOTO 10 

1 3PR " DEST I NAT I ON " : G0SUB8 1 : I NPUTK : K=K-# 1 OFF * < K= 1 ) -#SFFE * < K=2 ) 

14IF( <K<V)AND<K>=0) ) OR < (K>S) AND <K< X) ) OR < <K>=Z) AND <K<0> )PR"*NO DEST":G0T013 

15L=0: IF < J=V) AND <S> (TOP-1 ) =127) L=TOP-V-l 

161=0: IFK<0G0SUB82:G0T019 

17*<K+I)=*<J+I) :PR*<K+I) :DO: 1 = 1 + 1 : UNTILS) <J + I ) =13: 1 = 1 + 1 : G0SUB8: IFXO0G0T017 

1 90 < K+ 1 ) = 1 27 : G0SUB90 : GOTO 1 

20PR*(U+#93) :G0SUB80: PR "destination"; : I NPUTK: IFK=OGOT01 

21PR"source start ";: INPUTJ : PR"source end";:INPUTL 

25D0: S>K=S)J : K=K+1 : J=J + 1 : UNTIL J >L: GOTOl 

30PR*<U+#A8) :GOSUB80:PR"start at " ; : INPUTJ: IFJ=OGOT01 

33F0R I = J TO J +255STEP 1 6 : N=5># 1011: G0SUB70 : N=5># 1 1 : G0SUB70 : PR " " ; 

35*S=" ":F0RK=0T015:L=I+K:N=S>L:G0SUB70:PR" "; 

36IF <N>31 ) AND (N< 127) S (S+K) =N 

37NEXTK: PR" " , *S: NEXTI : G0T030 

40PR* <U+#BA) : G0SUB80 

41PR"":PR"dec = "; : INPUTD: N=S>#1007: G0SUB70: N=S>#1006: G0SUB70: IFD=OGOT01 

42G0T041 

50PR*<U+#D2) ;, "source"; : INPUTJ: PR"printer on": : INPUT*T 

51 PR* J : DO: J=j + 1 : UNTILS)J = 13: J=J + 1 : DELAY200: IF5)J < M27GQT051 

52 PR"print OFF" : INPUT*T: GOTOl 

70*T="00" : 5) <T+1 ) =MOD <N, 16) +48: 5>T=N/ 16+48: 5)T=5)T- <5)T>57) %7 

715><T+1)=3(T+1)-<5><T+1) >57) *7:PR*T; : RETURN 

80PR"<0> EXIT TO MENU": RETURN 

81PR"<1> RAM (#1100) " sPR"<2> EPROM" : PR" 'address > OTHER" : RETURN 

82PR"length="; : IFL=OL=J : DO: L=L+1 : UNTIL^L=127: L=L-J 

83PRL+1, "bytes": IFL>2047PR"*N0 FIT <cont>":STOP 

84PR"Turn on +25" ; : INPUT*T 

85*<K+I)=*<J + I) :PR*(K+I~4096) : IF3 (K+I-4096) OS) ( J + I ) PR"*BAD BIT" -.STOP 

86D0: 1 = 1 + 1: UNTIL*) (J + I) = 13: 1 = 1 + 1 : G0SUB8: IFXO0G0T085 

87PR"turn OFF 25V" : INPUT*T: RETURN 

90PR"":PR*(U+#65) : PR*S: G0SUB80: PR"< 1 > go to dest ": INPUTH: I FHOl RETURN 

9 1 S>#FFD4=S># 1014: S)#FFD5=S)# 1015 

92 1 = I +K : I FK >OS)#FFD6=S># 1010: 9#FFD7=:D# 1011 

Listing 1. Utility programs for our 8073 system are Dump, Move, Copy Memory, Dec/Hex and LList. 



38 Microcomputing, December 1981 



The microprocessor actually halts during this interval. 

Programming the System 

Generally speaking, this system programs like bigger 
computers. National Semiconductor has two publica- 
tions that contain detailed information on the language. 
Using NSC Tiny BASIC is a 20-page summary of the lan- 
guage which will be adequate for anyone who has had 
previous programming experience. The NSC Tiny BASIC 
User's Manual is much more detailed, with some pro- 
grammed instruction. The presentation is somewhat un- 
even, and there are a few minor errors, but it would be 
excellent for those who have never programmed in any 
high-level language. It is not possible to cover the lan- 
guage in detail in this article, but we can offer some hints 
and information that will help in programming: 
•Program lines may contain multiple statements sepa- 
rated by a colon. 

•Maximum line length is 72 characters. 
•A string is any sequence of numbers or ASCII 
characters terminated with a carriage return. There is no 
limit to the length of a string. 

• Each statement is stored literally, not as a single-byte 
token. For example, PRINT requires five memory 
locations. 

•Including the optional LET will speed program 
execution. 

•Multiple statements on a line generally speed execution. 
•Use parentheses in complicated arithmetic expressions. 
•Memory can be saved (although it's cheap these days) 
by leaving out optional words, remarks and extra spaces, 
and by using more than one statement per line. 
•The break key will stop normal program execution. 
Control-C must be used to break an INPUT statement. 
•More than one program may reside in RAM at one time 
but only the current program may be modified. How- 



Location (Hexadecimal) 


Function 


0000-09FF 


BASIC interpreter ROM 


OAOO-OFFF 


Programmable Interface 


1000-17FF 


First 2K of RAM 


1800-1FFF 


Second 2K of RAM 


2000-3FFF 


Unused 


4000-7FFF 


Data Rate Select 


8000-87FF 


First 2K of EPROM 


8800-8FFF 


Second 2K of EPROM 


9000-9800 


EPROM programmer 


9800-9FFF 


Peripheral Device Select 


A000-BFFF 


Unused 


C000-FFBF 


Data Rate Select 


FFC0-FFFF 


Internal 64 bytes of RAM 


Fig. 4. Memory map indicating the 


memory locations of the various com- 


ponents of the system. 





Data Rate 


Dl 


D2 


110 


H 


H 


300 


L 


H 


1200 


H 


L 


4800 


L 


L 


Fig. 5. These data rates achieved by four combinations of high/low inputs. 



MULLEN 

S-lOO PRODUCTS 

| EXTENDER BOARD WITH LOGIC PROBE $89 assm/tested 

with these features for use in testing your S-100 boards. 

• Logic probe with display shows; (H) for TTL logic 
high, (L) for low, (0) for open or 3-state, and 
(P) for pulse. 

• Pulse catcher switch latches (P) aids in detecting 
infrequent pulses. 

• Jumper links in +8 and +16 volt lines allow 
current measurement, switching and fusing. 

• Interlaced signal and ground traces reduce noise. 

• Pushbutton reset allows restarting test programs. 

• Formed leads on both sides of the edge connector 
for easy scope probe attachment. 

• Prototyping area and regulated 5 volts allows 
construction of special test circuits on the board. 

• Edge connector label shows signal names and pin numbers. 

• 5 1/2" high, on quality FR-4 material, solder masked 
and gold plated on mating surfaces. 

2 INDUSTRIAL EXTENDER BOARD $99 ass. /tested 
saves time where many boards are tested every day. 

• ZERO-INSERTION FORCE edge connector. 

• Switch and indicator light control +8 and +16 volt 
power. 

• Pushbutton reset allows restarting test programs. 

• Fuses in power lines protect test computer. 

• Interlaced signal and ground traces reduce noise. 

• Formed leads on both sides of edge connector for 
easy scope probe attachment. 

• Edge connector labels show signal names and pin numbers 

• 6" high, on quality FR-4 material, solder masked and 
gold plated on mating surfaces. 

3 RELAY OPTO-ISOLATOR CONTROLLER BOARD $219 ass ■/ tested 
for signal switching, or controlling low power devices. 

• 8 reed relays. 

• 8 opto-isolators with input bridge rectifiers, 
series resistors, and filter capacitors. 

• 256 switch selectable port addresses. 

• Removable terminal block for use with up to 
16 AWG wire. 

• LED indicators in relay drive circuits. 

• Socket for input simulation or testing. 

• Quality FR-4 material, solder masked & gold plated 
on bus connector. 

• Instructions Include programming examples. 

4tRIAC OPTO-ISOLATOR CONTROLLER BOARD $219 assm/tested 
for controlling line voltage AC devices. 

• 8 trlacs with snubbers for controlling inductive 
loads, and zero crossing isolated drive circuitry. 

• 8 opto-isolators with input bridge rectifiers, 
series resistors, and filter capacitors. 

• 256 switch selectable port addresses. 

• Removable terminal block for use with up to 
16 AWG wire. 

• LED indicators in triac drive circuits. 

• Socket for input simulation or testing. 

• Quality FR-4 material, solder masked & gold plated 
on bus connector. 

• Instructions include programming examples. 

MULLEN COMPUTER PRODUCTS ^37 
BOX 6214, HAYWARD, CA 94544 

OR PHONE (415) 783-2866 • VISA/MASTERCHARGE ACCEPTED 

INCLUDE $1 .50 FOR SHIPPING & HANDLING 

CALIFORNIA RESIDENTS ADD TAX 



Microcomputing, December 1981 39 



Super 

Compuprism 

Color Graphics 



. • - 



•* 



WmmWfmmfm 



For the S-100 Bus. 32K of on board memory 
allows a 288 H. x 192V. dot matrix, for a total 
of 55,296 pixels. Every pixel is programable in 
any one of 1 6 colors or 1 6 grey levels 
completely independent of all other pixels in the 
matrix . 

Compuprism Bore Board with documentation 
$45, kit $240, ass. and tested $280. 
(16K Memory 144H. x 192V.) 

Super Compuprism Bare Board with 

documentation $50, kit $350, ass. and tested 

$395 

(32K ^4emory 288H. x 192V.) 

Add $ 1 5 to A & T price for 1 6 level grey scale . 
Add $ 1 5 to A & T price for memory 
management port 

Compuprism software package, includes alpa- 
numberics, point plot, line draw, and TRS-80* 
graphics simulation $20 or FREE with A & T unit. 



Z-80 Users 

You Can Usol 

TRS-80 * 

Software 



We offer an assembled hardware 
interface which we guarantee 
will load data from TRS-80* 
cassettes into any Z-80 based 
system. (Except sealed units.) 
The documentation explains how 
to patch the TRS-80* software 
to your system. In fact you can 
virtually change your Z-80 
machine into a TRS-80* without 
making a single hardware 
change The documentation also 
includes an example of patching 
SARGON II** into a Z-80 
system . 

The price is $30 or FREE with the| 
purchase of an assembled 
compuprism or super compuprism 
unit. 

AD, DA Board 

S-100 board provides 16 chan- 
nels of analog to digital input 
and 8 channels of digital to 
analog output. With on board 
kluge area. Total cost of board 
and parts less than $120. Bare 
board with documentation $45. 



ALL COD ORDERS SHIPPED WITHIN 72 HOURS. 4MHz MOD FOR S.D. SYSTEMS. 
EXPANDORAM $10. 

J.E.S. GRAPHICS, P.O. Box 2752 
Tulsa, OK 74101, (918) 742-7 1 04 

TRS-80* is a trademark of Tandy Corp. •'ISO 

SARGON II* * is a trademark of Hayden Book Co. 



MBC SYSTEMS INC. (203) 342-2747 



COMPUTERS 

NORTH STAR 

•ADVANTAGE 64K-QD $3550 

HRZ-2-64K-DD-ASM $CALL 

HRZ-2-64K-QD-ASM $CALL 

HEWLETT-PACKARD 

HP-85A $2 795 

HP-83A $CALL 

ZENITH Z-89 ALL-IN-ONE-COMPUTER $2275 

ATARI 800 16K $ 759 

400 16K $ 345 

COMMODORE BUSINESS MACHINES 

8032 LARGE 80 COLUMN SCREEN $CALL 

CBM.PET COMPUTER 32K LIMITED TIME & QUANITY $ 975 

8050 DUAL FLOPPY DRIVE 1 MEG STORAGE $CALL 

INTERTEC SUPERBRAIN 64K-DD $2775 

PRINTERS 

DIABLO 630 LETTER QUALITY DAISY WHEEL PRINTER SCALL 

NEC 7710/7730 LETTER QUALITY PRINTER $CALL 

C.ITOH LETTER QUALITY PRINTER $1499 

OLYMPIA ES-100 TYPEWRITER/PRINTER ALL INTERFACES AVAILABLE. ... $1250 

IDS PAPER TIGER 445G $CALL 

460G $CALL 

560G 132 COLUMN 15" PAPER $1150 

ANADEX 9500/9501 132 COLUMN 15" PAPER $1290 

EPSON MX-80 WITH FRICTION ATTACHMENT $CALL 

MX-70 $395 

MX-100 132 COLUMN, 15" PAPER, FRICTION & TRACTOR SCALL 

OKIDATA MICROLINE 80 $ 375 

MICROLINE 83 132 COLUMN, 15 "PAPER, BI-DIRECTIONAL $ 750 

VERBATIM DISKETTS 

525-01/10/16 (10 PER BOX) $24.50 

550-01/10/16 (10 PER BOX) $3 7.50 

TERMINALS 

TELEVIDEO 920C $ 850 

950 $1050 

ZENITH Z19 $ 820 

INTERTUBE III OR EMULATOR $ 725 

ZENITH 12" GREEN MONITOR $ 139 

LEEDEX/AMDEK 100 GREEN MONITOR $ 165 

ABOVE ITEMS MAY BE ORDERED BY MAIL OR PHONE. VISA AND MASTER CHARGE 
FACTORY SEALED, MANUFACTURERS WARRANTY. PRICES AR E SUBJECT TO CHANGE 

Multi-Business Computer Systems Inc. 

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PORTLAND, CONN. 06480 «•*• 

M-F 9-6 SAT. 9:30-3:00 TWX 710 "8-6345 



ever, the others may be listed and run. 

• Pushing the reset button does not destroy the contents 

of RAM or your program but it does destroy the program 

pointers. You can still run or list the program but you 

can't modify it without changing the pointers. 

•The interpreter accepts only uppercase characters but 

it can print both upper and lowercase. 

•The first statement of an auto-run EPROM must be 

CLEAR. 

To begin writing a program, you must give the comput- 
er a beginning address. The interpreter allocates the first 
256 bytes of RAM. Since RAM starts at 1000 (hexadeci- 
mal) the first available location for the user is 1100. Any 
higher RAM address may also be used. This BASIC uses 
the # symbol to designate a hexadecimal number. Thus 
you enter: 

>NEW#1100 

You now tell the computer that you want to start a new 

program: 

>NEW 

The interpreter writes an end-of -program marker (127) 
into 1 100, effectively erasing the previous program as far 
as the interpreter is concerned. The interpreter is now 
ready to begin entering your program into RAM. 

System Utility Library 

Utility programs can provide the user with handy soft- 
ware to aid in developing, debugging and storing pro- 
grams. Most utilities for small systems (and many large 
systems) include an abbreviated notation that must be re- 
ferred to if the utility is not often used. A menu-driven 
utility with prompting in everyday English significantly 
reduces the hassle. Our routines have as many error- 
catching features as memory would allow (2048 bytes are 
used). A very brief overview of the utilities (given in 
Listing 1) follows: 



♦ 5V 



DO 
Dl 
D2 
D3 
D4 
D5 
D6 

D7 

AO 
A I 
A2 



17 



14 



15 



8 



18 



11 



20 



21 



25 



29 



23 



NRDS 
NUPS 

NWDS 




6 
22 




hj 



12 



ADC0809 



DO 
Dl 
D2 

D3 
D4 
D5 
D6 
D7 

AO 
Al 
A2 



OE 

ST 
LE 



INO 
INI 
IN2 

IN3 
IN4 
IN5 
IN6 
IN7 



CK 



DG 



AG 



J 



26 



27 



28. 



ANALOG 
> INPUTS 
0-5V 



10 



CLOCK 



16 



Fig. 6. Eight-channel, eight-bit AID converter. 



40 Microcomputing, December 1981 



Now for theTRS-80 Models I & 





• DOUBLE Sided & DOUBLE Density support. 
♦AUTOMATIC Density recognition. 

• 35, 40, 77, 80 and any other track counts are supported. 

• All available drive stepping rates are supported. 

• Hard Drive support, can be HANDLED AS A SINGLE DRIVE. 

• Hard drive partitioning, one drive can act as up to six. 

• Intermix 5", 8" and Hard drives, up to a total of 8 drives. 

• Compatible with the Model I Radio Shack Expansion Interface. 

• Upward compatible with TRSDOS (2.3 & 1.2 as documented). 

• Fully supports Microsoft language products for the TRS-80. 

• Complete media compatibility Model I to Model III and back. 

• Full support for LOBO's LX-80 interface. 

• Full support for AEROCOMP LC double density controller(DDC). 

• Full support for PERCOM's DOUBLER II. 

• Complete documentation (well over 250 pages). 

• Complete technical information. 

• A TOLL-FREE 800 number for customer service. 

• An LDOS users bulletin board on MicroNET. 

• A Quarterly LDOS users magazine (The LDOS QUARTERLY). 

• A liberal update policy. 

• An enhanced BASIC (LBASIC) including: 

> Upward compatible with Microsoft Basic. 

> High speed LOAD and SAVE. 

> Run multiple programs with common variables. 

> BLOCKED (variable length) files are supported. 

> DOS commands may be executed from LBASIC. 

> Built in string array. SORT. 

> Single stepper for debugging. 

> Several new statements and file modes. 



• A compiled JOB CONTROL LANGUAGE ( JCL). 

• CONVert utility to move files from Model III TRSDOS. 

• An Extended Debugging and Monitor program (with diskaccess). 

• CMDFILE for movement of disk and/or tape system (/CMD)f iles. 

• Device independent operation. 

•Full LINKing, ROUTEing, FILTERing and SETting are supported. 

• MiniDOS feature for constant access to certain DOS commands. 

• RS-232 DRIVER for serial support. 

• Sophisticated communications software included. 

• Wildcard characters and partial Filespecs are supported. 

• DATED FILES, show when a file was last written to. 

• Backup: Mirror, by Class, if Modified, by Date, by Extension, etc. 

• Selectable PURGE for fast disk "cleanup" of unwanted files. 

• Print formatter, for control of printer output. 

• Built in printer SPOOLER, to both disk and ram. 

• Joblog to record all system operations with time stamps. 

• UPPER and lower case support, throughout the system. 

• Blinking cursor with selectable cursor character. 

• 128 character TYPE AHEAD buffering for keyboard input. 
•Assign strings to individual keys with Key Stroke Multiply (KSM). 

• SUPER FAST operation with the SYSRES feature. 

• Extensive user control and system feedback. 

• Advanced PATCH utility for easy maintenance. 

• Complete transportability of software among all Z-80 LDOS 

systems through the use of the LDOS high ram supervisory 

call system (SVC). 

• Dealers to serve users Nationwide and in the Common Market. 

• The only DOS with a limited ONE YEAR WARRANTY" 

• Enjoy a professional operating system on YOUR TRS-80! 



* Specific hardware is required to use these features. 



The Ultimate In 
Operating Systems 
For Model I & 



Only $ 



169 

Version 5.1 



00 



* Model I LDOS provided on 35 track single density media. 

* Model III LDOS provided on 40 track double density media. 

* LDOS can be provided on special media configurations at an 
additional charge. 

* Prices & Specifications are subject to change without notice. 
+ Although not required, LSI recommends two or more drives 

when using LDOS. 



For Further Information Contact The Distributor Or Dealer Nearest You 



(West) 
LOBO DRIVES INT'L 

354 S. Fairview Ave. 

Goleta.CA 93117 

(805) 683-1576 



(Central) 
GALACTIC SOFTWARE LTD. 

11520 N. Port Washington Rd. 

Mequon, Wl 53092 

(414) 241-8030 



(East) 
MISOSYS 

5904 Edgehill Dr. 

Alexandria, VA 22303 

(703) 960-2998 



(The Common Market) 

MOLIMERX LTD. 

1 Buckhurst Rd., Bexhill 

Sussex, England 

(0424)-220391 



DEALER INQUIRIES WELCOME. LDOS is a product of LSI. TRS-80 & Radio Shack are trademarks. 




OGICAL 




INC. 



^322 



Mequon, Wl 53092 
(414)241-3066 




Fig. 7. A circuit, using an MM58174 real-time clock, that gives you an 8073 home energy and security management system 



42 Microcomputing, December 1981 



• DUMP— Prints lines of memory in hexadecimal and 
ASCII. 

•MOVE PROGRAM-Block-moves a BASIC program 
from EPROM or RAM to another RAM location. 
•COPY MEMORY-Copies any block of code from one 
part of memory to another. 

Either the MOVE or COPY command may be used to 
program an EPROM. The destination address is 9000, 
the EPROM programmer. 

•DEC/HEX— Converts any decimal number 0-32767 to 
its hexadecimal equivalent. (A hex/dec converter is built 
into the interpreter.) 

• LLIST— Sends the program text to a serial printer. 
You can enter this software into RAM, test it and, using 

its own EPROM routines, program a 2716 EPROM. Place 
the EPROM in the socket at U4, type <NEW #8800> 
and you are off. The prompting makes each routine self- 
explanatory. 

System Applications 

To program the system, you will need to communicate 
through the RS-232 port. This can be done with nearly 
any dumb terminal, a computer with a similar port, or 
one of the $150 terminal kits and your TV set. The inter- 
preter accepts only uppercase characters and operates in 
the full duplex mode. 

Before you can run, you must set the data rate. The 
data rate is programmed by strapping the inputs (P12, 14) 
of U9 either low or high. A data rate of 4800 bps is the 
usual choice for terminals. A pull-up resistor keeps 
D7 high during the data rate read time. (Fig. 5 lists the 
four combinations.) 

The next step is to set the pulse width of the EPROM 
programmer. Make sure that the socket at U4 is empty 
and place a scope probe on U7 to P6. Now enter the fol- 
lowing program: 

>NEW#1100 

>NEW 

>10 @ #9000 = 255 : GOTO 10 

>RUN 

Adjust the 20k potentiometer until the pulse width 
(positive) is just 50 ms. When properly adjusted, about 16 
pulses per second will be seen. Setting it more than 55 ms 
may damage EPROMs and less than 45 ms may result in 
incomplete programming. 

Hard copy of your programs can be printed by a low- 
cost serial printer or the 8255 can be programmed to han- 
dle a Centronics or similar parallel interface. We use Ep- 
son MX-70 printers in our systems with software written 
in machine language to get the maximum printing speed. 
The BASIC interpreter was an invaluable aid in writing 
that software. Once the program is written, debugged 
and committed to EPROM, the terminal does not need to 
be used. For example, a simple security system might 
have only switch inputs, and indicator and alarm outputs. 

A common need for both industrial and home applica- 
tions is analog-to-digital (A/D) conversion. An ideal chip 
for this system is the ADC0809 (National and Texas In- 
struments), which is an eight-channel, eight-bit convert- 
er with a to +5V input range. The clock signal can be 
divided down from pin 7 of the 8073 oscillator or it can 
be a simple two-gate oscillator. The interface for this chip 
is shown in Fig. 6. 

This 50-cent interface illustrates the simplicity of the 
bus structure. The software is also uncomplicated. A/D 
conversion is started by writing to the channel number 

^See List of Advertisers on page 210 




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memory, PUNK II constructs your program on disk. 
You gain complete use of your computer's memory, 
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PUNK II also constructs applications larger 
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Ideal for use with all popular high level 
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Reach out towards the infinite through PUNK 
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Microcomputing, December 1981 43 



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you want. Since the 100 /is conversion time of the 
ADC0809 is faster than the command interpretation, you 
can read out the data in the same program line. The one- 
line program below prints out A/D channel as fast as 
the interpreter can execute the instructions (about 35 
conversions and printouts per second). The is arbitrary 
and could be any number. (The software examples have 
extra spaces for clarity and include helpful remarks. 
These could be omitted in an actual program.) 

>10 @#9800 = : PRINT @#9800 : GOTO10 

A program to convert and print out all eight channels is 
still relatively simple: 

>10FORX = 0TO7 

>20@(#9800 + X) = 

>30 PRINT @(#9800 + X); 

>40 NEXTX : PRINT"" : GOTO10 



REM SCAN ALL 8 CHANNELS 
REM CONVERT 
REM PRINT IT 
REM DO IT AGAIN 



The trailing semicolon in line 30 suppresses the car- 
riage return so that all eight channels are printed on one 
line. The statement PRINT "" performs a carriage return 
and line feed. Despite using about twice as much code as 
the first example, the speed is still more than 25 conver- 
sions per second [joystick heaven!). 

Here in Colorado, we're facing another large energy 
cost increase this winter. More homeowners are consid- 
ering energy-saving devices, such as automatic setback 
thermostats. Using a computer system for this task has 
several advantages over electromechanical devices. You 
can have as many different cycles as you need without 
increasing the cost. It can easily control other energy-sav- 
ing devices. It has the power and flexibility to simultane- 
ously perform other tasks, such as home security. 

In our state, 45 percent of the cost of a setback thermo- 
stat is deductible from income taxes (30 percent state, 15 
percent federal). Fig. 7 shows a possible application. The 



key to this circuit is a National MM58174 real-time clock 
which counts seconds, minutes, hours and dates. You 
can access any of these counters separately. Other real- 
time clock chips could also be used. 

A thermistor connected to the A/D converter can be 
placed near your present thermostat. One output of the 
8255 drives a small relay that controls the off/on cycles of 
the furnace. 

Also shown is a peak demand controller that could be 
used both in home and industrial environments. In most 
localities, the power company will sell electricity at a re- 
duced rate if your usage is below a certain peak value. 
Say that you have an electric home with the heat on in all 
rooms. When you turn on the electric dryer, the line cur- 
rent exceeds the peak limit. Your computer system could 
temporarily shut down the heat in the laundry room to 
compensate. The scheme measures the total ac current, 
detects when the peak has been exceeded and goes to a 
lookup table to determine what to shut down. Using a 
real-time clock, the table could vary according to the time 
of day. It's easy to see that tuning up the system is so much 
easier by changing the software rather than hardware. 

Other inputs and outputs can handle the security sys- 
tem. Even in this simple application, the computer system 
is less expensive than the assortment of components need- 
ed to do the same task. It's convenient to be able to quickly 
step through the program to check the external hardware. 

Industrial users often need to prompt operators. This 
has usually been done with back-lighted buttons or nu- 
meric displays. There are now a number of alphanumer- 
ic displays that readily interface with computers. The 
major advantage of alphanumerics is that all the mes- 
sages may be completely spelled out and require only a 
few minutes on the keyboard to change. This feature 



♦ 5V 



♦ 5V 



t 



10 



vcc 



DL24I6 



CUE 



ra m m m 

ffl ffl a 



COM _>«/_ 



DO Dl 02 03 04 05 06 A0 A 



II 



12 



13 



14 



17 



16 



15 



8 



CLWRCSI CS2 



A 



A 



DO Dl D2 D3 D4 D5 D6 AO Al 



NWDS 



DL24I6 



szi m 

ZN 0\ 



S3 S3 

03 03 



v C c 



COM 



CUE 



DO D 



II 



D2 D3 D4 D5 D6 AO Al C 



L WR CSI CS2 



12 



13 



14 



17 



15 



8 



t 





A2 



NRST NUPS 
Fig. 8. Simple interface needed for an eight-digit alphanumeric display. 



44 Microcomputing, December 1981 




o NEW PRODUCTS! 

NOW AVAILABLE FROM AUTOMATED EQUIPMENT 



TELEVIDEO SYSTEM I 

The Televideo System I is a CP/M® based single- 
user computer system. State-of-the-art design and 
single board construction accounts for Televideo's 
reliability and exceptional price performance. 
Cobal. Basic, PL/1 and Fortran are just a few of the 
high level languages available. As your needs grow 
so can your Televideo computer system. The 
System I can be a satellite computer of a larger 
network of user stations using the multi-processor 
multi-tasking System II or System III. System I 
includes TS-81 computer, Televideo 910 terminal 
(950 terminal available at additional cost) and 
CP/M® 2.2. Nation wide on-site service is available 
through General Electric service company. 

System I specifications: Z80A. 64K Ram, 4K diag- 
nostic Eprom, two 5" 360K drives, serial and parallel 
port. 





CP/M® is a licensed product supplied by Digital 
Research, Inc. 

See Televideo System Ad. 



NORTHSTAR ADVANTAGE 
COMPUTER 

The Northstar Advantage Computer is an integrated 
package including full graphics capability. Line 
charts, bar graphs, pie charts and 3 dimensional 
displays are all possible as part of Northstars 
optional graphics/DOS operating system or CP/M® 
graphics package. All Northstar applications soft- 
ware is available for the Advantage Computer. Slots 
for 6 additional expansion cards are included. 

Specifications: Z80A CPU, 64 K Ram, Green screen 
12" monitor, 240 x 640 pixel graphics resolution, 
sculptured typewriter-like keyboard, two 5" 360K 
drives. 

V.I.P.'s call A.E.I. 



ZENITH 

Zenith Data Systems with world famous quality and 
reliability are now available from A.E.I. TheZ89and 
Z90 are standalone micro computers with a one 
piece design that simplifies installation and opera- 
tion. With the board line of PeachTree accounting 
software and Micro-Pro word processing software 
the Zenith computers are the ideal small business 
systems. Heathkit/Zenith educational courses are 
available making the Zenith computer an excellent 
choice for the first time buyer. 

Zenith specifications: 

Z89— 48K ram standard, Z80cpu, 2 serial ports, built 
in 12" terminal, one 5" 100K drive, expandable. 

Z90— 64K ram standard, Z80 cpu, 2 serial ports, 
built in 12" terminal, one 5" 200K drive, expandable. 

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LOBO Add-On 

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Subsystems 

FOr Apple, TRS-80, S-100 

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APPLE 



•Double Density Controller 

3101 Minifloppy. $399 31011 Minifloppy w/mterface card $489 

8101CA One SA800 in cabinet w/power. DDC* Controller, cable and manual $1449 

8202CA Two SA800 in cabinet w/power. DDC* Controller, cable and manual $1889 

5101CA One SA850 in cabinet w/power, DDC* Controller, cable and manual $1759 

5202CA Two SA850 in cabinet w/power, DDC* Controller, cable and manual $2364 

LCA 22 Double Density Controller only $599 



S-100 BASED 
COMPUTERS 

MODEL NO DESCRIPTION 

4101C SA400 in cabinet w/power $369 

821 2C Two SA801 in cabinet w/power $1329 

521 2C Two SA851 in cabinet w/power $1799 



GENERAL 



MODEL NO DESCRIPTION 

821 2C Two SA801 in cabinet 

w/power $1329 

5212C Two SA851 in cabinet 

w/power $1799 



TRS80 



MODEL NO DESCRIPTION 

4101C SA400 in cabinet w/power $369 

81 01 C II One SA800 in cabinet w/power for Mod II $909 

8202C II Two SA800 in cabinet w/power for Mod II $1349 

LX80 Double density expansion interface $641 

RS232 Dual Serial Port Option $75 



is 126 



1 



master charge-] 

tMt N't «B*H« ■ *M, , 




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(805) 688-8781 



^See List of Advertisers on page 210 



Microcomputing, December 1981 45 



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46 Microcomputing, December 1981 



MOB = #9800 
>20 INPUT $B 
>30 GOTO 20 



eliminates costly and time-consuming hardware modifi- 
cation. The interface for the Litronix DL-1416 or DL-2416 
four-digit display is almost trivial. This is due in part to 
the fact that latching, decoding and character generation 
are built into the chip. Only three inverters are needed 
for eight digits of alphanumeric display. (See Fig. 8.) 

Note that the address lines A0 and Al are inverted to 
make the left-most digit 9800 (hexadecimal) and the right- 
most digit 9807. You can display information in several 
ways. For example, running the program below will il- 
lustrate the blazing speed of a string move and allow you 
to enter your own messages. 

REM DISPLAY ADDRESS 
REM GET $B AND DISPLAY IT 
REM DO IT AGAIN 

ASCII characters can also be directly poked into any of 
the eight locations using the @<expression> = ASCII 
statement. 

Conclusion 

The system we have just described is a powerful and 
flexible microprocessor system. The choice of CPU and 
careful circuit design has yielded a system that can be un- 
derstood by those with different levels of electronics 
background. Because it uses the BASIC language, even 
those who have no formal training in electronics can pro- 
gram the system. The basic system has sufficient I/O to 
meet the needs of most small controllers and can be ex- 
panded to control literally hundreds of external devices. 
The user can write programs, debug them and commit 
them to nonvolatile memory while sitting at his desk. 
Programming takes one-tenth the time of assembly-lan- 
guage programming at a cost of less than one-tenth of a 
development system. The system's low cost will make it 
useful for home as well as industrial applications. ■ 



Other Applications 

We have done a number of things not described in the article with 
our 8073 system. These involve the following: 

• 500 bit per second enhanced cassette interface 

• Parallel interface for the Epson MX-70/80 printers 

• Synthesized speech 

1. NSC Digitalker 

2. Votrax Type & Talk 

• Eight-channel 12-bit A/D converter 

• Various D/A converters 

• 128-channel, two- wire serial data acquisition and remote control 
•Carrier control of remote line operated devices (BSR type) 
•Various machine-control applications 

• Nonvolatile RAM data save 

• Numeric and alphanumeric displays 

1. Low cost, numeric, eight-digit LED with single chip driver 

2. 64 character, LED, alphanumeric 

3. 32 character, LCD dot matrix, alphanumeric 

4. 40 character, vacuum flourescent, dot matrix, alphanumeric 

• Software 

1. BASIC text line editor 

2. Advanced utilities for both BASIC and object-code programming 

3. Assembler for object-code programs 

4. Disassembler for object-code programs 

5. Parallel printer interfaces with handshaking 

6. Numerous subroutines in BASIC and object code for control 
applications. 

The computer in this article is available as a kit ($175). The kit in- 
cludes all components, screened and solder-masked PC board, 2K 
bytes of RAM, a 2716 programmed with utility library and 150 pages 
of documentation ($25, separately). Octagon Systems Corp., 2849 
West 35th Ave., Denver, CO 80211. (303-458-1705). 

^See List of Advertisers on page 210 



SPECIAL DELIVERY 



WORDPROCESSING 

• POWER - 

for the TRS-80® 

"...If you're presently looking for a mailing list proc- 
essor, this represents the current state of the art." 

80 MICROCOMPUTING - 80 REVIEWS - JULY 1980 

MAILFORM is data entry at its best, just fill in 

the form! FAST, EASY to use functions include: 

search, sort, extract, page forward and back. 

Transparent cursor', insert /delete characters, 

and MORE! 

MAILRITE prints 'personalized' form letters 

by inserting information from MAILFORM into 

Electric Pencil®, Scripsit®, or BASIC text files. 

Print letters, labels, even envelopes! Boldface, 

underscore, change margins, pause, print 

'unprintable' characters, and MORE! 

XTRAl includes: MAILFORM; MAILRITE - 
with capability of printing variable text from 
a 'key' file; MAI LA BEL - 1, 2, 3, or 4 across 
label printer; and MAILSORT - sort a full 
40 track double density data diskette in 
only 48K! 

ALL MACHINE LANGUAGE 

means unsurpased 

SPEED. RELIABILITY & EASE OF USE 
For VISA, Master Card & COD orders only 

Call NOW - TOLLFREE 

(800) 824-7888 

ASK FOR OPERATOR 203 

California (800) 852-7777 
Hawaii & Alaska (800) 824-7919 

For more information call (214) 233-3998 
(Requires min 32K single disk drive) 

FOR THE MODEL I & III 

SPECIAL DELIVERY $125 

XTRA SPECIAL DELIVERY .. $199 

FOR THE MODEL II 

SPECIAL DELIVERY $199 

(Raquir** Mod II DOS varaion 2.0) 

TKS 80 is a reqislered trademark ol. Tandy Corp 












mastei charge 



software concepts 

• 385 ■» 

13534 Preston Rd. Suite 142 
Dallas, Texas 75240 

Dealer Inquiries invited 

Microcomputing, December 1981 47 



4 K STATIC RAM 



iTt 



I 



2114 LOW POWER 200 NS 



74LS00 



74C00 CMOS 



74LS00 


25 


74LS123 


.90 


74LS259 


2.80 










74LS01 


.25 


74LS124 


2.95 


74LS260 


.60 










74LS02 


.25 


74LS125 


.90 


74LS261 


2.45 










74LS03 


.25 


74LS126 


.80 


74LS266 


.50 










74LS04 


.25 


74LS132 


.75 


74LS273 


1.60 


74SX 


.40 


74S163 


3.70 


74LS06 


25 


74LS136 


.50 


74LS275 


3.X 


74S02 


.45 


74S168 


4.X 


74LS06 


.30 


74LS138 


.75 


74LS279 


.X 


74S03 


.45 


74S169 


5.40 


74LS09 


25 


74LS139 


.75 


74LS280 


1.95 


74S04 


.75 


74S174 


1.X 


74LS10 


25 


74LS145 


1.10 


74LS283 


.95 


74S05 


.75 


74S175 


1.X 


74LS11 


.X 


74LS147 


2.25 


74LS290 


120 


74S08 


.45 


74S181 


4.45 


74LS12 


.X 


74LS148 


1.25 


74LS293 


1.X 


74S09 


.75 


74S182 


2.X 


74LS13 


.40 


74LS151 


.75 


74LS295 


1.X 


74S10 


.X 


74S188 


3.X 


74LS14 


.75 


74LS153 


.75 


74LS298 


.95 


74S11 


.X 


74S189 


14.X 


74LS15 


.X 


74LS155 


.90 


74LS299 


2.X 


74S15 


.X 


74S194 


2.X 


74LS20 


.25 


74LS156 


.90 


74LS323 


3.95 


74S20 


.X 


74S1X 


1.X 


74LS21 


.30 


74LS157 


.75 


74LS324 


1.75 


74S22 


.75 


74S1X 


4.X 


74LS22 


.25 


74LS158 


.75 


74LS347 


1.95 


74SX 


.45 


74S197 


420 


74LS26 


.X 


74LS160 


.90 


74LS348 


1.95 


74S32 


.X 


74S201 


14.X 


74LS27 


.35 


74LS161 


.90 


74LS352 


1.X 


74S37 


1.X 


74S225 


8.X 


74LS28 


.35 


74LS162 


.90 


74LS353 


1.X 


74SX 


1.X 


74S240 


3.X 


74LS30 


.25 


74LS163 


.90 


74LS363 


1.X 


74S40 


.40 


74S241 


3.70 


74LS32 


.35 


74LS164 


.90 


74LS365 


.X 


74S51 


.75 


74S251 


1.X 


74LS35 


.55 


74LS165 


.90 


74LS366 


X 


74S64 


.75 


74S253 


7.40 


74LS37 


.50 


74LS166 


2.00 


74LS367 


.65 


74S65 


1.20 


74S257 


1.X 


74LS38 


.35 


74LS168 


1.70 


74LS368 


.65 


74S74 


.X 


74S258 


1.45 


74LS40 


.25 


74LS169 


1.70 


74LS373 


1.15 


74S85 


2.X 


74S260 


1.X 


74LS42 


.50 


74LS170 


1.70 


74LS374 


1.75 


74SX 


1.40 


74S274 


19.X 


74LS47 


.75 


74LS173 


.75 


74LS375 


.65 


74S112 


1.X 


74S275 


19.X 


74LS48 


.75 


74LS174 


.90 


74LS377 


1.40 


74S113 


1.X 


74S2X 


2.X 


74LS49 


.75 


74LS175 


.90 


74LS385 


1.85 


74S114 


1.45 


74S287 


4.70 


74LS51 


25 


74LS181 


2.10 


74I S3flR 


.X 


74S124 


2.75 


74S2X 


4.40 


74LS54 


.35 


74LS189 


9.95 


74LS390 


1.85 


74S132 


1.X 


74S289 


6.X 


74LSX 


.35 


74LS190 


.95 


74LS393 


1.85 


74S1X 


.X 


74SX1 


6.X 


74LS63 


120 


74LS191 


.95 


74LS395 


1.X 


74S134 


.X 


74S373 


3.40 


74LS73 


.35 


74LS192 


.80 


74LS399 


1.65 


74S1X 


1.45 


74S374 


3.40 


74LS74 


.40 


74LS193 


.90 


74LS424 


295 


74S138 


1.X 


74SX1 


7.X 


74LS75 


.50 


74LS194 


.95 


74LS447 


.35 


74S1X 


120 


74SX7 


5.70 


74LS76 


40 


74LS195 


.90 


74LS490 


1.X 


74S140 


1.40 


74S412 


2.X 


74LS78 


.50 


74LS196 


.80 


74LS630 


75.X 


74S151 


1.15 


74S471 


9.X 


74LS83 


.75 


74LS197 


.80 


74LS640 


3.X 


74S153 


1.15 


74S472 


16.X 


74LS85 


1.10 


74LS221 


1.15 


74LS641 


3.X 


74S157 


1.15 


74S474 


17.X 


74LS86 


.40 


74LS240 


1.15 


74LS642 


3.X 


74S158 


1.40 


74S482 


15.X 


74LS90 


60 


74LS241 


1.15 


74LS645 


3.X 


74S161 


2.X 


74S570 


7.75 


74LS91 


.80 


74LS242 


1.85 


74IS668 


1.65 


74S162 


3.70 


74S572 


7.75 


74LS92 
74LS93 


.65 
.60 


74LS243 
74LS244 


1.85 
1.00 


74LS669 
74LS670 


1.85 

O IK 










2>10 










74LS95 


.80 


74LS245 


1.95 


74LS674 


9.X 










74LS96 


.80 


74LS247 


.75 


74IS68? 


3.15 










74LS107 


.40 


74LS248 


120 


74I S683 


225 










74LS109 


.40 


74LS249 


.95 


74LS684 


2.X 










74LS112 


.40 


74LS251 


125 


74I .S685 


2.X 






OA 


f\ 


74LS113 


.40 


74I S253 


.80 


74LS688 


2.X 






Ml 


1 1- 


74LS114 


.50 


74LS257 


.80 


74LS689 


2.X 






\J\J 


w 


74LS122 


.45 


74LS258 


.80 















74CX 


X 


74C1X 


2.X 


74C02 


X 


74C221 


2.X 


74C04 


X 


74C240 


2.X 


74CX 


X 


74C244 


2.X 


74C10 


X 


74C373 


2.70 


74C14 


1.45 


74C374 


2.70 


74C20 


X 


74CX1 


.X 


74CX 


X 


74C902 


.X 


74C32 


.X 


74C903 


.X 


74C42 


1.70 


74C904 


.X 


74C48 


2.X 


74C9X 


10.X 


74C73 


X 


74CX6 


X 


74C74 


.X 


74CX7 


.X 


74C76 


1.X 


74CX8 


2.X 


74C83 


1.X 


74C909 


2.70 


74CX 


.X 


74C910 


9.X 


74CX 


4.X 


74C911 


9.X 


74CX 


1.70 


74C912 


9.X 


74C93 


1.70 


74C914 


1.X 


74CX 


1.70 


74C915 


1.X 


74C107 


X 


74C917 


2.70 


74C1X 


5.70 


74C918 


1.X 


74C151 


2.X 


74C920 


16.X 


74C154 


3.X 


74C922 


5.X 


74C157 


1.75 


74C923 


5.X 


74C1X 


1.X 


74C925 


6.70 


74C161 


1.X 


74C926 


7.X 


74C162 


1.X 


74C927 


7.X 


74C163 


1.X 


74C928 


7.X 


74C164 


1.X 


74C929 


7.X 


74C1X 


1.X 


74C9X 


7.X 


74C173 


1.X 


74C932 


1.X 


74C174 


220 


74C941 


2.75 


74C175 


2.X 


74C9X 


9.X 


74C192 


2.X 


80CX 


X 


74C1X 


220 


80CX 


.X 


80C97 


.X 


88CX 


3.X 


82C19 


4.X 


88C29 


3.X 





41 




;mos 






II II 


4X0 


.X 


4040 


.X 


4X1 


.X 


4X1 


X 


4041 


.95 


4602 


X 


4002 


.X 


4042 


.75 


4503 


X 


4X6 


X 


4043 


X 


46X 


8.X 


4X7 


.X 


4044 


X 


45X 


125 


4X8 


.X 


4046 


.X 


4X7 


X 


4009 


.45 


4047 


.X 


45X 


1.95 


4010 


.45 


4048 


.75 


4510 


.X 


4011 


X 


4049 


.56 


4511 


.X 


4012 


X 


4050 


.55 


4512 


.X 


4013 


.45 


4X1 


.X 


4514 


225 


4014 


.X 


4052 


X 


4515 


225 


4015 


X 


4053 


.X 


4516 


1.X 


4016 


.45 


4065 


2.75 


4618 


125 


4017 


X 


4056 


2.75 


4519 


125 


4018 


X 


4059 


9.X 


46X 


125 


4019 


.45 


4060 


125 


4522 


125 


4020 


X 


4X6 


.75 


4526 


125 


4021 


X 


4068 


.40 


4527 


1.75 


4022 


.X 


4069 


.40 


4628 


125 


4023 


X 


4070 


.40 


4531 


.X 


4024 


.75 


4071 


.X 


4532 


1.75 


4025 


X 


4072 


.X 


45X 


1.75 


4026 


1.96 


4073 


.X 


4543 


1.95 


4027 


65 


4075 


.X 


4553 


4.X 


4028 


80 


4076 


.95 


4555 


.95 


4029 


X 


4078 


.X 


45X 


.X 


4030 


.45 


4081 


.40 


4558 


2.25 


4031 


1.50 


4082 


.40 


4568 


5.X 


4032 


2.75 


4065 


95 


4581 


1.X 


4033 


2.75 


4086 


X 


4582 


1.95 


4034 


2.75 


4093 


.X 


4584 


X 


4035 


X 


4094 


3.X 


45X 


X 


4037 


2.X 


4099 


1.75 


4702 


9.X 



206-643-0792 







LINEAR 




7X5CT 


.X 


LMX1V 


.75 


LMX7V 


125 






LMX6V 


.75 


LM723 


X 


781 2CT 


.X 


LMX9K 


1.50 


LM733 


.X 


781 5CT 


.X 


LM311V 


X 


LM741V 


.X 






LM317T 


1.90 


LM747 


.75 


78XKT 


1.40 


LM317K 


3.75 


LM748V 


.X 


781 2KT 


1.40 


LM318N 


1.50 


LM1414 


1.50 


781 5KT 


1.40 


LM323K 


3.75 


LM 1458V 


.X 


78LX 


.X 


LM324N 


.X 


DS1488N 


1.X 


78L12 


.X 


LMX7K 


3.X 


DS1489D 


1.X 


7X5CT 


.X 


LM339 


.75 


LM1889 


2.45 


791 2CT 


.X 


LM377 


2.25 


LM39X 


.X 


791 5CT 


1.15 


LM3X 


125 


LM3909 


.X 






LM3XV 


1.25 


LM3914 


3.75 


7X6K 


1.X 






LMX15 


3.75 


791 2K 


1.50 


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iH 



An elegant solution to unscramble word puzzles. For the PET, Apple or TRS-80. 



Popping and Pushing 
Permutations in BASIC 



By Kenneth Wasserman 



A permutation of a sequence of ob- 
jects is a rearrangement of their 
order. Occasionally, when writing a 
program, one needs to compute all 
possible permutations of a group of 
objects. Most people with some 
mathematical background will know 
that given N objects there will be N! 
(read as N factorial, representing the 

product N x (N-l) x (N-2) x x 

2x1) ways of permuting a given se- 
quence. However, when it comes to 
explicitly listing all these N! se- 
quences, people are often hard- 
pressed to come up with a general 
algorithm. 

Some Motivation 

Why, you might ask, would anyone 
want an exhaustive list of all possible 
arrangements of a series of objects? 
Edward Rager, in his article entitled 
"Scramble" (Microcomputing, Janu- 
ary 1981, p. 78), provides a program 
to assist the user in solving anagram 
puzzles, words or phrases whose let- 
ter or word positions have been re- 
arranged to mask their true spelling 
or meaning. He suggests that his pro- 
gram is of great help in unscrambling 
such puzzles often presented in the 
game sections of newspapers. His 
program will output all possible letter 
permutations of any word given as 
input, providing that the word has 
either three, four, five or six letters. 
The restrictions on word length arise 
because each word length is treated 
by a separate subroutine in BASIC. 

50 Microcomputing, December 1981 



To handle the four cases of different- 
length words, Rager needs to use 
about 80 BASIC statements, not 
counting input, output or remarks. 

This article will present a more 
general algorithm that uses only 
seven BASIC statements. 

Rager' s general strategy is to use 
brute force in listing all permutations 
of three-letter words, and to use this 
subroutine as the kernel for longer 
words. That is, a four-letter word is 
handled by removing the first letter 
and permuting the remaining three 
by use of the "brute force" sub- 
routine. Then the second letter is re- 
moved, and the new group of the 
three remaining letters is permuted. 
Next the third letter is held back, and 
again the three-permutation is done. 
Finally, the last letter is removed, and 
the first three letters of the original 
word are permuted. 

At each stage the letter held back is 
concatenated to the front of each 
three-letter permutation before it is 
printed. Words five letters long are 
treated in a similar manner, except 
that the routine just described for 
four permutations is called after each 
one of the initial five letters is re- 
moved. Again, the letter is first stuck 
onto the front of the four-permuta- 
tion before it is printed. Six-letter 
words are similarly permuted. 

An Elegant Solution 

The basic concept embodied in 
Scramble is central to the functioning 



of a recursive program; that is, the so- 
lution to a problem by the use of a 
program segment which calls itself as 
a subroutine. To avoid a seemingly 
infinite number of subroutine calls, a 
recursive program usually has a con- 
ditional statement that checks to see 
if some base level has been reached. 
If this base level is reached, then a re- 
turn from a subroutine statement is 
executed, avoiding an infinite recur- 
sion. 

In Scramble, this base level is a 
word that is three letters long. How- 
ever, this program is not recursive in 
that each different-length word is in- 
itially handled by a separate subrou- 
tine; thus, no part of the program 
calls itself as a subroutine. 

Unfortunately, the BASIC language 
does not allow truly recursive sub- 
routines. This stems from the fact 
that all variables are global; that is, 
they are known to all parts of the pro- 
gram at all times. A recursive subrou- 
tine should allow for local variables 
known only within the subroutine 
and known only at one particular 
level in the recursion. The concept of 
a level of recursion is very useful if 

one wants to simulate a recursive 
routine in BASIC. To understand the 
idea of a level of recursion, as applied 
to the permutation problem, you can 
think of the length of the word that is 

Address correspondence to Kenneth Wasserman, 
154 W. 70th St, Apt. 6E, New York, NY 10023. 



being permuted as the level of recur- 
sion. 

For example, if you wanted to use a 
recursive procedure to find all per- 
mutations of the word CAT, you 
would start at level 3. You would 
remove each letter and call the per- 
mutation procedure with the 
"words" AT, CT and CA. Each of 
these two-letter words would be pro- 
cessed at level 2 in the procedure. In 
level 2 you would call the permuta- 
tion subroutine at level 1 with the 
word A and then with T for the word 
AT. You would do a similar call with 
C, T and C, A for the words CT and 
CA, respectively. Finally, in level 1 
each word would simply cause a 
return of itself. Level 1 is the base 
level so that it defines the enumera- 
tion of permutations of a one-letter 
word as only that single letter. 

After reaching level 1, the proce- 
dure pops back up to level 2, where 
the letter that was removed is con- 
catenated onto the front of the word. 
The second letter of the word at level 
2 is then removed and you push 
down to level 1, which then pops 
back up to level 2, where the re- 
moved letter is stuck onto the front of 
the single-letter word. Having fin- 
ished both letters of the word at level 
2, the procedure pops up to level 3 
and proceeds with processing the 
next letter of the three-letter word, 
CAT. When all processing is com- 
plete at level 3, it finally pops back up 
to the main program, which called 
the permutation procedure in the 
first place. 

All this pushing and popping sug- 
gests that a pushdown stack is a good 
way to implement recursive routines. 
Stacks are easy to handle in BASIC, 
and are thus what I will use to write 
this recursive routine. A stack is most 
easily implemented with a one-di- 
mensional array and a stack pointer 
or simply an index into the array. 
Thus, if you call the stack I and the 
stack pointer L, you can locate the 
next stack entry by I(L). To add an en- 
try on the stack you use L = L + 1 , then 
I(L) = entry. To remove an entry you 
use entry = I(L) and assign L = L-1. 

How to Do It 

You are now ready to describe per- 
mutations, a simple routine in BASIC 
for enumerating all possible permu- 
tations of a given word of unrestrict- 
ed length. This program was written 
in PET BASIC and works equally 
well on an Apple or TRS-80 (see Pro- 
gram listing). Lines 1000 through 
1060 contain the permutation sub- 



routine that does all the work. 

Only three variables are used by 
the subroutine. The variable L serves 
a dual purpose; it indicates the level 
of recursion as well as the length of 
the word at that level. I(L) is the push- 
down stack (described above) used to 
indicate what letter, at the current 
level of recursion, is to be removed 
from W$(L). W$(L) is the word to be 
permuted at level L. W$ is a variable 
used to hold the top level word need- 
ed by the print subroutine at line 
2000. 

The subroutine must be called with 
L set equal to the length of the word 
you wish to permute and with W$ 
equal to W$(L), the word itself. Line 
1000 checks to see if the base level of 
the recursion has been reached. If it 
has, the subroutine at line 2000 is 
called and the procedure pops back 
up to the next-higher level. Other- 
wise it sets up a FOR . . . NEXT type 
loop between lines 1010 and 1060. 

The counter variable I(L) is initial- 
ized to L in line 1010. Line 1020 in- 
serts the letter currently being re- 
moved at level L into the proper place 
in W$. Line 1030 forms the word to 
be permuted at the next lower recur- 
sive level. The actual recursive sub- 
routine call occurs in line 1040. Note 
that you must explicitly decrement 
and later increment the value of L, 
because all variables are global in 
BASIC and you need a way of keep- 



ing track of the current level. 

Lines 1050 and 1060 finish off the 
FOR . . . NEXT type loop by decre- 
menting the loop counter, I(L), and 
checking for termination. If the loop 
at level L is finished, the procedure 
returns to the next higher level; 
otherwise it goes to line 1020 and re- 
moves the next letter. 

The only operator used which 
might vary among versions of BASIC 
is the MID$ function. When given 
three arguments, MID$ will return 
the substring of the first argument 
starting at the position specified by 
the second argument with a length 
given by the third argument. How- 
ever, when only two arguments are 
given to MID$, it will return the sub- 
string of the first argument, starting 
at the position specified by the sec- 
ond argument and continuing until 
the end of the original string. If your 
version of BASIC does not have this 
feature, it should be easy enough to 
simulate using the LEN (length) func- 
tion. 

Hopefully, the user will find many 
other applications for this procedure 
and the techniques it uses. One possi- 
ble application involves analyzing 
playing card hands for numerical se- 
quences, as in poker or cribbage. All 
possible orderings can be generated 
and a simple check of each will deter- 
mine if a beneficial sequence exists 
within the hand.H 



10 

20 

30 

40 

50 

60 

70 

80 : 

100 

110 

120 

130 

140 

150 

999 

1000 

1010 

1020 

1030 

1040 

1050 

1060 

1999 

2000 

2010 

2020 

2030 

2040 

2050 



REM PERMUTATIONS BY KENNETH WASSERMAN 3/12/81 



EM THIS PROGRAM WILL LIST ALL POSSIBLE PERMUTATIONS OF THE WORD GIVEN AS 

EM INPUT. A RECURSIVE SUBROUTINE IN LINES 1000-1060 PRODUCES THE NEXT WORD 

EM TO BE OUTPUT. THE SUBROUTINE IN LINES 2000-2050 CAN BE USED TO SIMPLY 

EM PRINT THE REARRANGED WORD OR IT CAN BE EXTENDED TO REQUEST FURTHER 

EM ANALYSIS ON THE WORD PRESENTED TO IT. 



INPUT W$ 

L«LEN(W$) 

DIM W$(L),I(L) 

W$(L)«W$ 

G0SUB 1000 

END 

• 

IF L«0 THEN G0SUB 2000: RETURN 

KL)-L 

W$-MID$(W$.1,L-1)+MID$(W$(L),I(L),1)+MID$(W$,L+1) 

W$(L-1)«MID$(W$(L),1,I(L)-1)+MID$(W$(L).I(L)+1) 

L-L-l: G0SUB 1000: L-L+l 

I(L)-I(L)-1: IF I(L)«0 THEN RETURN 

GOTO 1020 

REM THIS SUBROUTINE IS PASSED A WORD IN THE VARIABLE W$ . NOTE THAT W$ 
REM IS A PERMUTATION OF THE ORIGINAL WORD INPUT TO THIS PROGRAM. ITS 
REM VALUE SHOULD NOT BE CHANGED BY THIS SUBROUTINE. 

• 

PRINT W$, 
RETURN 



Program listing. The Permutations program was written in BASIC on a Commodore PET, but it will 

run "as is" on an Apple II with Applesoft. It will also run on a TRS-80 with Level II BASIC if you add 

the following line: 

90 CLEAR 1000 

If you want to check the permutations of a ten-letter word, plan on spending a few days in front of your 

computer's display— there are 3,628,800 permutations to watch. 



Microcomputing, December 1981 51 



If you're a prospective computer buyer who's tired of hearing about "the other guys, " 

Intertec offers you another choice which is worth considering. 



The Secret World 
Of the Superbrain 



When I started in 1976 as a hard- 
ware hacker, I never thought I 
would own a machine as powerful as 
the Superbrain. In those days IK 
bytes of 2102 RAM and a hex display 
were all that anyone could ask for. 
Today I can pick up a phone and or- 
der a full system which can be de- 
livered within the week. Which is ex- 
actly what I did. 

I started with some basic criteria. 
First, I wanted a system that wasn't 
strung together with cables and ex- 
pansion boxes. Second, I wanted 
built-in disks and a proven operating 
system. Finally, I wanted a system 
that would accept Microsoft BASIC. 

I had just about chosen the Super- 
brain when Tandy unveiled the Mod- 
el III. Both computers sounded as if 
they were what I was looking for. I 



By Lawrence J. Bregoli 

took the trip to a nearby Radio Shack 
computer store. 

There it was sitting on the shelf— 
the Model III with dual disks, Micro- 
soft BASIC and TRSDOS. What more 
could you ask for? I wanted to tuck it 
under my arm and leave, and the 
salesperson knew it. 

Then he turned it on. It couldn't be 
true— a 64 character by 16 line for- 
mat, just like the Model I. I had ex- 
pected an 80 by 24 format. 

It was then that I decided. Since I 
wanted my system for text writing 
and editing, I felt that I needed an 
80-character format. I placed my or- 
der for the Superbrain. 

Vital Stats 

Since I had never used a CP/M 




operating system, I had a few funda- 
mentals to learn. The first two chap- 
ters of the manual give a brief over- 
view of the hardware. Its vital statis- 
tics include: 

•The Superbrain uses two Z-80 mi- 
croprocessors, one for computing 
and screen functions and one for disk 
I/O. Both operate at 4 MHz. 
•Two types of disks are available: 
single-sided double-density and dou- 
ble-sided double-density (quad densi- 
ty). They hold over 350K and 700K 
bytes respectively. 
•Two memory sizes, 32K bytes and 
64K bytes, are available. 
•The display size is 80 characters by 
24 lines, with upper- and lowercase 
displayed in a 5 x 7 matrix on a 7 x 10 
field. A 15 MHz CRT is used. 
•There are two built-in RS-232 asyn- 
chronous serial ports and a 40-pin 
Z-90A data bus. Intertec sells an op- 
tional S-100 adapter for this bus. 
•The main 62-key keyboard has a 
standard character set plus an alpha 
caps-lock, backspace, linefeed, 
break, delete, escape, here is, con- 
trol, return and a set of reset keys 
which must be pressed at the same 
time to cause a system reset. An 
18-key numeric keypad has its own 
enter key and four cursor control 
keys. 

•The operating system is CP/M ver- 
sion 2.2. 

System Programs 

The programs provided on the orig- 
inal diskette are shown in Table 1. 
Some of the programs unique to the 
Superbrain include 32CPM5/1, 
32CPM5/5, 64CPM5/1 and 64CPM 



Intertec's Superbrain QD features a double-sided drive system for over 700K bytes of disk storage and a 
full 64K of RAM. 

52 Microcomputing, December 1981 



Address correspondence to Lawrence J. Bregoli, 
106 S. Longyard Road, Southwick, MA 01077. 



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Microcomputing, December 1981 53 



5/5. All are different operating sys- 
tems for use with 32K and 64K ma- 
chines. The two programs ending in 
/l are used to convert programs creat- 
ed on earlier versions of the Super- 
brain to the present system. The only 
one of the above programs I use is 
64CPM5/5, to put the operating sys- 
tem on a newly-formatted diskette. 

The programs 32K TEST and 64K 
TEST are memory exercise tests to 
verify that the RAM is okay. 

The FORMAT program does what 
it implies— formats new diskettes. 

The TX and RX programs are used 
to transmit serial data through the 
RS-232 ports. The program TX/RX.- 
DES is a description of the TX and RX 
programs. 

SYSTEM. DES is a Superbrain DOS 
3.0 description. 

The program 32BS5/5.ASM is an 
assembly-language program which 
can be used to modify the BASIC I/O 
system. 

The CONFIGUR.COM program 
lets you configure the main and auxil- 
iary RS-232 ports to match the Super- 
brain to a peripheral piece of equip- 
ment. CONFIGUR allows you to set 
the baud rate (up to 9600 baud), 
number of character bits, number of 
stop bits and parity status for either 
port, and also handshaking on the 
auxiliary port. 

You may also configure the disk 
system to allow disk read-after-write 
verification. After making your 
changes, a new operating system is 
written onto your disk until you need 
to configure again. 

The rest of the CP/M programs 
make Superbrain a powerful ma- 
chine for assembly-language pro- 
gramming and file handling. 

My favorite computer-based lan- 
guage, however, is BASIC, and Mi- 
crosoft BASIC is the best of all those 
available. So after backing up and 
properly labeling my MBASIC5 disk- 
ette, I was ready to get started. 

(By the way, to run MBASIC5 on 
the Superbrain you need a 64K 
system. While Microsoft was packing 
all that power into MBASIC5, they 
made the interpreter 26K long. With 
this and a 12K monitor there's just 
not enough room in a 32K machine. 
With 64K you wind up with 28187 
bytes of available program space, 
which is enough for most program- 
ming needs. If you need more room, 
MBASIC5 makes it easy with the 
CHAIN command.) 

The power of MBASIC5 has been 
discussed in several articles appear- 

54 Microcomputing, December 1981 



ing previously in this journal. Some 
unique features of the Superbrain let 
you use MBASIC5 for some sophisti- 
cated programming. A few examples 
include: 

Absolute cursor addressing. A BASIC 
statement of the type 

100 PRINT CHR$(27)"Y"CHR$(ROW + 32) 
CHR$(COL + 32); 

where ROW ranges between and 23 
and COL ranges between and 79 
will place the next print position any- 
where on the screen. ROW = and 
COL = is the upper left-hand corner. 
Erase to end of line. The statement 

110 PRINT CHR$(27)CHR$(126)"K"; 

will erase data from the current cur- 
sor position to the end of the current 
line. 
Erase to end of page. The statement 

120 PRINT CHR$(27)CHR$(126)"k"; 

will erase data from the current cur- 
sor position to the end of the screen. 
Combinations of the statements 
can provide some interesting split 
screen programming. One of my fa- 
vorites is 

BLINKING: 

Using certain CHR$ codes in a 
BASIC program can make a character 
or group of screen characters blink. 
This feature can be used to make im- 
portant portions of your displayed 
text or prompts blink on and off. 

In BASIC, a statement of the type 

200 PRINT CHR$(27)CHR$(126)"B"; 

turns on the blinking mode for any 
text that follows and 

220 PRINT CHR$(27)CHR$(126)"b"; 

turns the blinking mode off. Any text 
printed to the screen between these 
two statements will blink, but the 
rest of the screen will have normal 
characters. Any text set in the blink- 
ing mode will remain blinking until it 
is scrolled off the screen. 

Reverse video. For those of you who 
would rather look at black on a white 
background, you can reverse the 
video with an OUT command from 
BASIC. The statement 

250 OUT &H68,&HC3 



will reverse the video system to a 
white background, while the state- 
ment 

260 OUT &H68.&H43 

will set the video back to normal. 

Display control characters. There 
are another 32 special characters cor- 
responding to the control code val- 
ues. They consist of arrows pointing 
in all four directions, plus two more 
arrows in the up-left direction and in 
the down-left direction. Other graph- 
ics included in this set are a small bell 
corresponding to the keyboard's 
CTRL"G" command and various 
other underlined numbers and let- 
ters, plus a set of up and down 
chevrons. 

To get at these characters from 
BASIC you again use the CHR$ 
codes. The statement 

300 PRINT CHR$(27)CHR$(126)"E"; 

will enable the transparent mode for 
these control characters. A following 
statement of the type 

310 PRINT CHR$(X); 

where X is between and 31, will pro- 
duce one of the control codes printed 
on the screen. If X falls between 128 
and 160, the control codes will be dis- 
played in the blinking mode. 

Cursor Controls. As stated previ- 
ously, the numeric keypad has a set 
of cursor control keys labeled with 
arrows in four directions. These keys 
plus the tab key on the standard 
keyboard are all functional under 
BASIC, and are handy for text editor 
programs. The break key is not allo- 
cated in BASIC and may be used in 
any fashion you wish under program 
control. 

Conclusions 

I have not covered all the features 
of the Superbrain. But I hoped to get 
across that other computers are out 
there. These computers offer many 
special features which a computer 
user may want or need in his applica- 
tion; we shouldn't ignore them be- 
cause we don't read about them 
regularly. ■ 



32CPM5/5 COM 


64CPM5/5 COM 


32CPM5/1 


1 

COM 


64CPM5/1 COM 


32KTEST COM 


64KTEST 


COM 


FORMAT COM 


32BS5/5 ASM 


SYSTEM 


DES 


TX COM 


RX COM 


TX/RX 


DES 


CONFIGUR COM 


HEXDUMP COM 


SUBMIT22 


COM 


XSUB22 COM 


ED22 COM 


DUMP22 


COM 


ASM22 COM 


LOAD22 COM 


SYSGEN22 


COM 


STAT22 COM 


PIP22 COM 


DDT22 


COM 


Table 1. System diskette programs. 





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Medical(PAS-3) $849/$40 

Dental (PAS-3) $849/$40 

ASYST DESIGN 

Prof Time Accounting $549/$40 

General Subroutine $269/$40 

Application Utilities $439/$40 

COMPLETE BUS. SYSTEMS 

Creator $269/$25 

Reporter $169/$20 

Both $399/$45 

COMPUTER CONTROL 



MICROTAX 

>s Individual $250 

s Professional $1000 

>s Partnership $750 

s Package $ 1 500 

ORGANIC SOFTWARE 
TextWriter III $ 1 1 1/525 

DateBook II $269/$25 

Milestone $269/$30 



PASCAL 

Pascal/MT + 
Pascal/Z 

Pascal/UCSD4 
Pascal/M 



$429/$30 
$349/$30 
$429/$50 
$189/$ 20 



Fabs(B-tree) 
UltraSort II 



$159/$20 
$159/$25 






COMPUTER PATHWAYS 

Pearl (level 1) $ 99/$25 

Pearl (level 2) $299/$40 

Pearl (level 3) $549/$50 

DIGITAL RESEARCH 

CP/M 2 2 

NorthStar $149/$25 

TRS-80 Model II (P+T)$159/$35 

Micropolis $ 1 69/$25 

Cromemco $189/$25 

PL/l-80 $459/$35 

BT-80 $179/$30 

Mac $ 85/$ 15 

Sid $ 65/$ 15 

Z-Sid $ 90/$ 15 

Tex $ 90/$ 15 

DeSpool $ 50/$ 10 

CB-80 $459/$35 

CBasic-2 $ 98/$20 

DMA. 

Ascom $149/$ 15 

DMA-DOS $179/$35 

CBS $369/$45 

Formula $539/$45 

GRAHAM-DORIAN 

General Ledger $729/$40 

Acct Receivable $729/$40 

Acct Payable $729/$40 



OSBORNE 

General Ledger 
Acct Rec/Acct Pay 
Payroll w/Cost 
All 3 

All 3 + CBASIC-2 
Enhanced Osborne 
With C Basic 



WORD PROCESSING 

WordSearch $179/$ 50 

SpellGuard $229/$25 

VTS/80 $259/$65 

Magic Wand $289/$45 

Soell Binder $349/$45 



$ 59/$20 
$ 59/$20 
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$129/$60 
$199/$75 
$269/$60 
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PEACHTREE" 

General Ledger $399/$40 

Acct Receivable $399/$40 

Acct Payable $399/$40 

Payroll $399/$40 

Inventory $399/$40 

Surveyor $399/$40 

Property Mgt $799/$40 

CPA Client Write-up $799/$40 

P5 Version Add $129 

SOFTWARE WORKS 

Adapt (CDOS to CP/M) $ 69/$na 

Ratfor $ 86/$na 



SOHO GROUP 

MatchMaker 
Worksheet 



$ 97/$20 
$177/$20 



$729/$40 
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Payroll II 

Inventory II 

Payroll 

Inventory 

Cash Register $493/$40 

Apartment Mgt $493/$40 

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S-Basic $269/$25 

Selector IV $469/$35 

MICRO DATA BASE SYSTEMS 

MDBS $269/$35 

MDBS $795/$40 

DRSorQRSorRTL $269/$10 
MDBS PKG $1295/$60 

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Customization Notes 
Mail-Merge 
WordStar/ Mail-Merge 
DataStar 
WordMaster 

SuperSort I 

Spell Star 



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<s GL or AR or AP or Pay $849/$40 
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Analyst $199/$25 

Letteright $179/$25 

QSort $ 89/$20 

NAD $ 87/$20 

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Diagnostic I $ 49/$20 

Diagnostic II $ 84/$20 

Disk Doctor $ 84/$20 

Forth (8080 or Z80) . . $ 1 49/$30 

Fortran $219/$30 

Fortran w/Ratfor $289/$35 

s C Compiler $ 1 74/$20 

-'Star Edit $189/$30 

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Target 


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MicroStat 


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Visicalc 3 3 $159 

Desktop/Plan II $159 

Visiterm $129 

Visidex $159 

Visiplot $149 

Visitrend/Visiplot $229 

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FMS-80 $649/$45 

dBASE II $595/$50 

Condor II $899/$50 

Access 80 Level 1 $249 

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Access 80 Level 3 $679 

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Microcomputing, December 1981 55 



Sooner or later, as certain as death and taxes, you'll need to expand your system. Here's an inexpensive 

way to expand the memory of your Superboard II or Challenger CI P. 



Poor Man's Memory 
Expansion for the OSI 



By John E. Young 



The Ohio Scientific Superboard II 
and Challenger C1P are excellent 
values for the money, giving you up 
to 8K memory, an 8K BASIC-in-ROM, 
cassette interface, 50 key upper and 
lowercase keyboard, and many other 
features on a single board. All you 
need to add is a TV or monitor and a 
cassette recorder, and you are up and 
running. 

But as the saying goes, "Into every 
life some rain must fall." Expansion 
of this computer is a rather expensive 
proposition— the OSI 610 expansion 
board with an additional 8K memory 



6ND 


• 


40 


1 


• 


IRQ 


GNO 


• 


39 


2 


• 


NMI 


GNO 


• 


38 


3 


• 


DD 


GND 


• 


37 


4 


• 


BOO 


BD4 


• 


36 


3 


• 


BDI 


BD5 


• 


35 


6 


• 


BD2 


BD6 


• 


34 


7 


• 


BD3 


BD7 


• 


33 


8 


• 


GND 


R/W 


• 


32 


9 


• 


GND 


02 


• 


31 


10 


• 


GND 


GND 


• 


30 


II 


• 


1 N/C 


GND 


• 


29 


12 


• 


A2 


GND 


• 


28 


13 


• 


Al 


AI5 


• 


27 


14 


• 


AO 


AI4 


• 


26 


13 


• 


A3 


AI3 


• 


23 


16 


• 


A4 


AI2 


• 


24 


17 


• 


A5 


All 


• 


23 


16 


• 


A6 


AIO 


• 


22 


19 


• 


A7 


A9 


• 


21 


20 


• 


A8 



Fig. 1. Pin assignments for OSI 40-pin DIP sock- 
et. 

Address correspondence to John E. Young, 6701 
King Court, Woodridge, IL 60517. 

56 Microcomputing, December 1981 



is $300, a cost very nearly equal to 
that of the original computer system. 
The 610 board does have a number of 
other features— sockets and decoding 
for a total of 24K memory, peripheral 
interface adapter for use with disk 
drives and buffering of all signals for 
use with an expansion bus that can be 
purchased separately. But if you're 
interested only in expanding memory, 
the 610 board is too expensive. 

Fortunately, I've found a very inex- 
pensive way to add up to 16K addi- 
tional memory. The interface board 
described here couples the new 
memory board to the OSI computer 
as well as a 44-pin bus, which will let 
you construct and add peripherals at 
minimum cost. 

In addition, you can double the 
baud rate for the cassette interface, to 
improve the speed with which you 
can load programs or data into the ex- 
panded memory. 



OSI Expansion Capabilities 

The main CPU board of the Super- 
board II/C1P (600 board) has a 40-pin 
DIP socket for connecting most pe- 
ripherals that require parallel data. 
This socket provides output for the 
address, data and necessary control 
signals. The pin assignments for this 
socket are shown in Fig. 1. 

The bidirectional data lines are buf- 
fered on the 600 board by means of 
8T28 transceivers. The 600 board ac- 



tually contains only the sockets for 
these two 8T28s; you must install 
these in the U6 and U7 positions to 
use the expansion connector. 

The direction of data through the 
transceivers is controlled by the DD 
signal that is generated by whatever 
peripheral is using the data lines at 
any moment. More details regarding 
the DD signal will be presented later, 
in the discussion of the memory board 
and the interface circuits. 

The 16 address lines, clock (02), 
and read/write (R/W) signals are not 
buffered on the OSI 600 board, so 
buffers must be provided on an inter- 
face board. In addition, interrupt re- 



UNREG 14V 
GND 



DD 



BDO 

BDI 

BD2 

BD3 

BD4 

BD5 

BD6 

BD7 

NMl 

Fro 



22 Z 

21 Y 

20 X 

19 W 

15 V 
17 U 

16 T 
IS S 
14 R 
13 P 
12 N 
II M 
10 L 
9 K 

6 J 

7 H 
6 F 

3 E 

4 
3 C 
2 6 
I A 



5.0 V 
B 02 

B R/W 

B R/W 

B02 

BAIS 

BAI4 

BAI3 

BAI2 

BAII 

BAI0 

BA9 

BAB 

BA7 

BA6 

BA5 

BA4 

BA3 

BA2 

BAI 

BAO 



Fig. 2. Edge connector for 44-pin bus. 



quest (IRQ ) and nonmaskable inter- 
rupt (NMI) lines are included for 
CPU control by external peripherals. 
The socket is wired so that when a 
40-conductor ribbon cable is connect- 
ed to the socket, the cl ock a nd control 
signals 02, R/W, DD, IRQ and NMI 
are isolated from each other and the 
data and address lines by means of 
ground lines to minimize possible in- 
teraction among these signals. There 
is one unused pin in the 40-pin socket 
that could be used for some other sig- 
nals as the need arises in the future. 
These signals should provide for 
the fundamental needs of just about 
any peripheral you would attach to 
an expansion bus. Additional control 
signals can be synthesized as neces- 
sary, such as the two extra signals re- 
quired by the memory board used in 
this expansion. 

Bus Structure 

To minimize cost, the bus is based 
on double-sided 22/44 pin sockets 
with 0.156 inch spacing. These con- 
nectors are readily available, either 
in solder or wire-wrap configuration. 
These sockets accept 4 x 4.5 inch hob- 
by prototyping boards, which are 
quite inexpensive yet hold an ade- 
quate number of ICs if space is used 
efficiently. The interface between the 
OSI 600 board and the memory ex- 
pansion board is constructed on one 
of these boards and fits into one slot 
of the bus. 

The pin assignments for the bus are 
essentially the same used in KIM- 
type buses, but a number of the KIM 
control signals are omitted, since 
they are not available from the OSI 
600 board. The pin assignments for 
the b us are shown in Fig. 2. 02 and 
R/W are not directly supplied by the 
OSI 600 board but are generated and 
buffered on the interface board and 
then supplied to the bus. There are a 
number of unused lines in the bus 
which can be used for specialized sig- 



Hex 


Address Line Status 




Code 


15 


14 


13 


12 


11 


10 


1 F F F 


L 


L 


L 


H 


H 


H 


2000 (1) 


L 


L 


H 


L 


L 


L 


3 FFF 


L 


L 


H 


H 


H 


H 


4000 


L 


H 


L 


L 


L 


L 


5FFF (2) 


L 


H 


L 


H 


H 


H 


6000 


L 


H 


H 


L 


L 


L 


7000 


L 


H 


H 


H 


L 


L 



(1) Starting address for 16K memory expansion 

(2) Final address for 16K memory expansion 

Fig. 3. Binary coding of high order address lines 
for hex 2000 to 5FFF. 



nals as peripherals are added to the 
system. 

I have included both a 14-V unreg- 
ulated and a 5.0 V regulated line on 
the bus. The 5.0 V line is controlled 
by the 7805 voltage controller power- 
ing the interface board. The interface 
board uses less than 200 mA of the 
1500 mA capacity of the 7805, so if a 
peripheral board is constructed that 
contains a moderate number of ICs, it 
can be powered from the 5.0-V line. 
Otherwise, the peripheral should 
have its own voltage regulator pow- 
ered from the 14-V unregulated line. 

Memory Expansion Board 

The memory board used in this sys- 
tem is a 16K static RAM board de- 
signed for the SS-50 bus (SWTP 6800 
computer) and sold by Digital Re- 
search Corp. (PO Box 401565, Gar- 
land, TX 75040). Digital Research 
currently sells the bareboard for $30. 
This board uses 2114s, which can 
now be bought for about $4 each. All 
support components for this board 
are readily available and inexpensive 
($2 for the most expensive chip). All 
told, you can buy and assemble this 
board with 8K memory for $100- 
$125, and when you add the cost of 



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Microcomputing, December 1981 57 



♦ 5V 
n 



Ttry—E> 



VMA 



fljg. 4. Exclusive OR gate for generating VMA sig- 
nal needed by memory board. 




JUMPER TO 5V 

Fig. 5. Jumper configuration for memory address 
selection on the Digital Research memory board. 



shown on the Digital Research in- 
struction sheet, the scheme shown in 
Fig. 5 is used. Only one conventional 
jumper is used— between pins 2 and 
7. Pin 4 is tied high by means of a 
jumper to somewhere on a regulated 

5.0-V line. 

Because of the modified address 
decoding, the first 8K of the 16K 
available of the board resides at the 
high end of the memory board. If you 
populate only half the memory board, 
the 21 14s must be installed in sockets 
9 through 16 and 25 through 32 rather 
than 1 through 8 and 17 through 24. 

The data direct (DD) signal needed 
by the transceivers on the OSI 600 
board is taken from the memory 



board by running a jumper from ei- 
ther pin 8 of IC 35 or pin 15 of ICs 38, 
39 or 40 of the memory board to an 
unused spot on the 50-pin connector 
area at the edge of the board. 

Rather than attach a plug-in con- 
nector to the edge of the memory PC 
board, I simply soldered two 16-con- 
ductor ribbon cables directly to the 
terminations at the board edge. At the 
other end of each of the ribbon cables 
is a standard 16-pin DIP connector. 
Hence the memory board is connect- 
ed directly to the interface board by 
means of these cables, rather than go- 
ing through the hassle of wiring up a 
single 50-pin edge connector dedicat- 
ed to the memory board. 



the interface board and bus sockets, 
you still have laid out only about half 
the cost of the OSI 610 board. 

The board has its own voltage regu- 
lators, so you need to supply at least 8 
V of unregulated power. All data, ad- 
dress and control lines are directly 
available from the OSI 600 board 
(through appropriate buffers) with 
the exception of two— 32 and VMA 
(valid memory address). These sig- 
nals are synthesized on the interface 
board. 

The memory on the Digital Re- 
search board is addressed in 16K 
blocks starting from address 0000, 
4000, 8000 or C000 hex. The 16K 
memory expansion for the OSI sys- 
tem must start at 8K (2000 hex) and 
end at 24K (5FFF hex), so the mem- 
ory addressing scheme on the Digital 
Research board must be modified. 
The binary configuration of the high 
order address lines for the appropri- 
ate hex addresses is shown in Fig. 3. 
As can be seen from this chart, for the 
range of memory addresses of inter- 
est for the OSI expansion, either ad- 
dress line 13 or 14 is high. For ad- 
dresses outside the critical range, 
lines 13 and 14 are either both low or 
both high. Hence an exclusiv e OR 
gate can be used to generate the VMA 

signal for the memory board. The 
schematic of the exclusive OR gate is 
shown in Fig. 4, which is actually in- 
stalled on the interface board de- 
scribed later. 

To complete the modified address 
decoding, the address selection jump- 
ers normally used on the Digital Re- 
search board must also be changed. 
The selection is carried out by means 
of jumpers installed in an eight-pin 
socket on the memory board. Rather 
than using any of the configurations 

58 Microcomputing, December 1981 



♦ 5V 



40 
39 
38 
37 



12 
13 
14 

It 

19 

20 



2 

g 

3 



15 
16 
17 
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24 
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27 



§ 31 
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BOB 


BOS 










































BOS 


BD4 












































B04 


BD3 














































B03 


802 
















































B02 


B0I 
































- 


















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BOO 


















































BOO 


Frq 




- <M 
> O 
3 ID 


o 
a 


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IB 


o 

CD 


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s 

OD 


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t < 

3 OD 


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o 

< 


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< 
CD 


CO 

1 

CD 


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CD 


< 


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CD 


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CD 


O 

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$a> >3t-t/>oro-Z2_i*:>-ouju.<ico<->x~> 



INTERFACE BOARD EDGE CONNECTOR FOR 44 -PIN BUS 

Fig. 6. Schematic of interface board. 



151 

14 

13 

3 

4 

15 

8 

9 

II 

5 

12 

7 

10 

6 

2 

I 

I6l 

I 

15 

2 

14 

3 

13 

4 

12 

5 

II 

6 

10 

7 

9 

8 



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or 
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>- 

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Interface Board 

This board supplies the signal buf- 
fering and modification necessary for 
both the memory board and the bus. 
The overall schematic of this board is 
shown in Fig. 6. 74LS367s are used 
for buffering of the address lines, 
R/W and 02. (OSI's R/W is equivalent 
to the Digital Research R/W signal.) 
There are four unused buffers in ICl 
in case additional signals are brought 
into the bus or from the OSI 600 
board. Since it was necessary to pro- 
duce an inverted 02 for the memory 
board, the buffered S2 is sent to the 
bus as well, in case any other periph- 
eral requires 52. An inverted read/ 



write signal (R/W) is also generated, 
buffered and sent to the bus. The ex- 
clusi ve OR gate necessary to generate 
the VMA signal for the memory 
board uses two of the four gates on a 
74LS86. 

This board contains the 40-pin DIP 
socket for the ribbon cable coming 
from the OSI 600 board, wired ac- 
cording to Fig. 1. Two 16-pin DIP 
sockets are wired according to Fig. 7 
for the ribbon cables leading to the 
memory board. The connector sock- 
ets and interface ICs are all installed 
in the interface board using wire- 
wrap connections. 

The data direct (DD) line tells the 
computer that a peripheral is putting 
valid data onto the bus. This line is 
held high by a voltage divider on the 
OSI 600 board and must be pulled 
low (sinking approximately 23 mA) 
by any peripheral transmitting to the 
bus. This can be done with a 7417, an 
open collector driver capable of sink- 
ing 40 mA. 

With open collector drivers on each 
peripheral that supplies a DD signal, 
a high impedance path is presented to 
the bus unless it is pulled low by its 
own peripheral. In this way, current 
through the DD line and the drivers 
held in the low state is limited to the 
23 mA supplied by the pull-up divid- 
er at the transceivers. The 7417 for 
the DD signal supplied by the mem- 
ory board is located on the interface 
board. 

The NMI and IRQ lines to the OSI 
600 board are fed directly from the 
bus without intermediate drivers. 
OSI holds these lines high at the 6502 
CPU chip with 4.7k resistors. Open 
collector buffers such as the 7417 
should be used in this case also, since 
there will be a possibility of multiple 
peripherals driving one or the other 
of these interrupt lines. 



N/C 


• It 1 • 


VMA 


• 19 2 • 


N/C 


• 14 3 • 


N/C 


• IS 4 • 


BAO 


• 12 9 • 


BA2 


• II 6 • 


BA4 


• 10 7 • 


BA6 


• 9 8 • 



BR/W 
B02 

N/C 

00 

BAI 

BA3 

BA3 

BA7 



S2 



BAB 
BAIO 
BAI2 
BAI4 
BD7 
BD5 
BD3 
B0I 



• 16 


1 • 


• 13 


2 • 


• 14 


3 • 


• 13 


4 • 


• 12 


3 • 


• II 


6 • 


• 10 


7 • 


• 9 


e • 



BA9 
BAII 
BAO 
BAI5 
BD6 
BD4 
BD2 
BOO 



SI 



Fig. 7. Sockets for two 16-conductor ribbon cables 
to memory board. 



General Construction 
Considerations 

The complete system is constructed 
in a box 8x12x6 inches. This box 
contains a seven-slot bus and the 
memory board, which is attached to 
spacers along one side of the box. Un- 
regulated 14 V dc is supplied to the 
box from a separate 10-amp power 
supply. The edge connectors for the 



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bus are mounted on 3/4x3/4 inch 
aluminum angles that run from end 
to end of the box. I have used wire- 
wrap connectors for the bus. An inex- 
pensive 22/44-pin motherboard is 
available from Electronic Systems in 
San Jose, CA, that would simplify 
wiring of this bus. 

Now that you have significantly ex- 
panded your memory from 8K to 16 
or 24K, you will quickly realize that 
loading that much data or program 
material from cassette tape at the 
Kansas City standard of 300 baud 
takes ages! You can easily cut that 
time in half with a very simple modi- 
fication to the OSI 600 board. 

OSI uses a 6850 asynchronous com- 
munications adapter for control of se- 
rial data. The transmit clock (pin 4) 
and the receive clock (pin 3) inputs of 
the 6850 are tied together on the PC 
board and driven by output from the 
clock counter. The trace on the PC 
board must be cut just beyond where 
the pins 3 and 4 are tied together. 
Leads are then soldered to each cut 
end of this trace and run to the proto- 
type section of the board. 

In this section of the board, I placed 
a 16-pin socket and a 74LS151 multi- 



Oruob 



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Microcomputing, December 1981 59 



600 BAUD CLOCK 


TO 





PIN 14 OF U60 




• 



16 



300 BAUD CLOCK TX CLK 



74LSI5I 



ACIA CLOCK INPUT TO 



PINS 3,4 OF UI4 



+ 5.0 V 



^ 



fey » 



ED 



CRN 



♦ 5.0V 



ir 6 ' 



Fig. 8. Baud rate selector and indicator. 



plexer. The multiplexer is used to 
avoid putting the clock pulses direct- 
ly through the switch. Direct switch- 
ing of the clock signals may not lead 
to problems, but this is a simple, yet 
elegant, way of doing the job. The 
clock signal for the 600 baud rate is 
obtained from pin 14 of U60. The 
switch then ties one select input on 
the multiplexer either high or low. 

The wiring scheme is shown in Fig. 
8. The output of the multiplexer (pin 
5) is connected to the clock input of 
the 6850 (pins 3, 4). The 300-baud 
clock input, taken from the other end 
of the cut trace (actually called the 
TX CLK signal), is input to pin 4 of 
the multiplexer. The 600 baud clock 



signal is input to pin 3. The enable 
signal (pin 7) and select lines 1 and 2 
(pins 9 and 10) of the multiplexer are 
grounded. Select line (pin 11) of the 
multiplexer is wired to one pole of a 
DPDT miniature toggle switch mount- 
ed on the front panel of the computer 
next to the keyboard. I added indica- 
tor LEDs— a green one for the stan- 
dard 300 baud and a red one for 600 
baud. 

I did not have to change the capac- 
itors in the cassette audio input sec- 
tion for use with 600 baud. Because I 
wanted to preserve the standard 
300-baud operation in order to use 
commercial software, I wanted to 
avoid having to make this change. 



Operation in the 600-baud mode 
has been just as reliable as with the 
300 baud, using a cheap cassette re- 
corder and cheaper cassettes. Even at 
600 baud, cassette read-and-write op- 
erations take a considerable amount 
of time for large blocks of informa- 
tion. I am currently investigating 
ways of improving this situation, 
without going to a disk system. 

Conclusion 

With this setup, I have doubled my 
system memory with the capability 
of adding yet another 8K, and have a 
six-slot bus structure that will permit 
considerable experimentation with 
peripherals. All this has been ob- 
tained for half the cost of the OSI ex- 
pansion board. Types of peripherals 
that I envision constructing for my 
bus are a multichannel A/D converter 
for home monitoring, ac switching 
gear for home control and sound or 
music boards. OSI now has these 
types of options available in their 
larger computer systems, but all that 
is at a price. Besides— it's more satis- 
fying to know that you've done it 
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60 Microcomputing, December 1981 



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Do your part for the energy conservation movement. Give your home a thorough energy analysis with this 

BASIC program that you can easily convert to your system. 



Take a Byte 
Out of Your Energy Bills 



By Paul J. Boudreaux 



Sooner or later everyone gets infu- 
riated when he finds that the local 
utility company plans to raise their 
rates again. This time I decided to dig 
out my old bills to see just what had 
been done to me over the last few 
years. 

After assembling the records it oc- 
curred to me that there was more 
here than met the eye. As a prac- 
ticing experimental research physi- 
cist, I recognized that this was a rec- 
ord of the energy used by my house 
for the past several years which 
reflected the local environmental 
stresses for each month. I also knew 
that to maintain a thermal balance in 
the home, the total energy put into 
the house had to equal the total 
energy flowing out of the house. Here 
then was a way of directly measuring 
the heat flow and the thermal 
resistance of my insulation and 
weatherproofing. 

Thus, by using my utility bills, I 
wrote a BASIC program for my F8 
system that will determine the effec- 
tive insulating capability, or R-value, 
of my house. The 9K floating-point 
BASIC version used on my home- 
brew F8 system was by Micro Busi- 
ness Systems, Inc., Box 8255 JFK Sta., 
Boston, MA 02114, who used the 
Fairchild FAIRBUG PSU ROM chip. 



Paul J. Boudreaux (Laboratory for Physical 
Sciences, 4928 College Ave., College Park, MDj is 
a senior research physicist specializing in the reli- 
ability and device physics of semiconductors. 

62 Microcomputing, December 1981 



The thermodynamics of home 
energy is complex and far beyond the 
scope of this article, but certain 
simplifications can be made. 

Heat flow takes one of three forms: 
radiation (e.g., sunlight striking the 
roof), convection (e.g., hot air rising 
up a chimney) and conduction (e.g., 
the flow of heat through a wall) . Al- 
though radiation and convection play 
important roles in the energy balance 
of a house, I'll concentrate on con- 
duction. 

Since conduction is generally the 
major heat-flow mechanism in the 
house, this simplifies things enor- 
mously. In this model, the relation- 
ship between conduction heat flow 
(H) and environmental temperature 
(T) is expressed as equation 1 in Table 
1. H is expressed in British thermal 
units (BTUs), or the amount of heat 
required to raise the temperature of 
one pound of water one degree Fahr- 
enheit. 

The inside and outside temperature 
difference is expressed by (Tin-Tout). 
A is the cross sectional area through 
which the heat flows and L is the 
length that it must travel. 

K is a constant of proportionality 
called the thermal conductivity. In 
the English system used in the U.S., K 
is numerically equal to the number of 
BTUs of heat energy conducted in 
one hour through a slab one inch 
thick and one square foot in cross sec- 
tion when the temperature difference 
between the faces of the slab is one 
degree Fahrenheit (F). 



Although the K value of any insula- 
tion can be found in physical con- 
stant tables, insulation is usually 
measured by a quantity called its 
R-value. The R-value of a material is 
simply its thickness in inches divided 
by the thermal conductivity. Thus, 
part of equation 1, K/L, is given for 
any particular piece of insulation by 
the reciprocal of its R-value. To deter- 
mine the R-value, you have to find 
the total area of insulation in square 
feet and the temperature difference 
between the inside and outside of the 
house in degrees Fahrenheit occur- 
ring for one hour. This is shown as 
equation 2 in Table 1, and forms 
the basis for the program shown 
in Listing 1. 

Knowing all these facts would be 
great if I were taking a high school 
physics exam, but I'm really after 
home insulation efficiency. I still 
need a measurement of the tempera- 
ture during the month. This infor- 
mation could be obtained from the 
local TV weatherman, but there is a 
much more useful quantity called a 
"degree day." 



H = — (Tin-Tout) Equation 1 
H = A(Tin-Tout) Equation 2 



Table 1. 




5 RESTORE 

10 DIM D$(72) 



Listing 1. BASIC Home Insulation Efficiency program. 



20 

40 

50 

60 

70 

76 

77 

78 

79 

80 

110 

120 

140 

142 

144 

148 

149 

150 

151 

160 

170 

180 

200 

210 

218 

220 

230 

235 

240 

250 

260 

300 

310 

320 

330 

340 

350 

355 

358 

360 

370 

375 

380 

382 

384 

386 

400 

410 

420 

430 

435 

440 

450 

482 

484 

485 

730 

740 

750 

760 

765 

766 

767 

770 
780 
790 
800 
820 
830 
835 

840 

850 

870 

875 

876 

880 

890 

900 

920 

930 

935 

940 

941 

942 

943 

944 

950 

951 

952 

953 

954 

955 

960 

965 

966 

970 

980 

990 

1000 

1010 

1020 

1025 

1030 



DIM 
DIM 
DIM 
DIM 
DIM 
DIM 
DIM 
DIM 
DIM 
DIM 
DIM 
DIM 



M$(36) 
T$(55) 
V$(80) 
Y$(4) 
X$(66) 
E(12,9) 
G(12,9) 
H(12,9) 
F(12,9) 
T(12) 
P(12,9) 
Q(12,9) 



EXTERIOR AREA IN SQ.FT. 



YR, Yl-END YR 



ENERGY (KWH X HEAT+COOL( D . D .X " 
DAYSEGY/DEG.DAY" 



YOU HAVE ELECTRIC HEATING FOR YOUR HOME? (YES OR NO)" 



.1)" 



1 



- "Y" THEN JO 
"Y" THEN 485 
YOU HAVE OIL HEATING 

J-l 



FOR YOUR HOME? (YES OR NO)"; 



REM A IS 

A-3375 

REM YO-BEGIN 

YO-1973 

Yl-1980 

V$-" ELECT. (KWH X GAS (THERMS X 

V$-V$+"( BTU/DEG.DAY X " 

T$-"ELECTRICITYNATURAL GASTOT. ENERGYDEGREE 

M$-"JANFEBMARAPRMAYJUNJLYAUGSEPOCTNOVDEC" 

X$ -«I 1 , j , j j x j x _ 

REM 1GAL #2 OIL- 1 . 4THERM , 1 THERM- 1 OOOOOBTU-29 . 302KWH 

REM 1 KWH - 0.034127 THERM 

T-0 

FOR M-l TO 12 

READ T(M) 

T-T+T(M) 

NEXT M 

L-10000 

0-10000 

FOR Y2-Y0 TO Yl 

Y-Y2-INT(Y2/10)*10 

FOR M-l TO 12 

READ E(M,Y),F(M,Y) 

NEXT M 

NEXT Y2 

J-0 

JO - 

PRINT"DO 

INPUT Y$ 
IF Y$(l 

IF Y$(l 

PRINT"DO 

INPUT Y$ 

IF Y$(1,1)-"Y" THEN 

FOR Y2-Y0 TO Yl 

Y-Y2-INT(Y2/10)*10 

FOR M-l TO 12 

READ G(M,Y) ,H(M,Y) 

IF J-l THEN G(M,Y)-1.4*G(M,Y) 

NEXT M 

NEXT Y2 

IF J-l THEN 

IF J-l THEN 

PRINT 

PRINT 

PRINT" 

PRINT 

PRINT"YEAR" 

PRINT 

P-0 

Q-0 

FOR Y2-Y0 TO Yl 

Y-Y2-INT(Y2/10)*10 

C-0 

F-0 

H-0 

FOR M-l TO 12 

READ Q(M,Y),P(M,Y) 

H-H+H(M,Y) 

F-F+F(M,Y) 

C-C+P(M,Y)+Q(M,Y) 

P-P+P(M, Y) 

Q-Q+Q(M,Y) 

NEXT M 

PRINT Y2,F,H,F+H,(F+H)/C 

NEXT Y2 

Ul-0 

PRINT 

PRINT 

PRINT"U IS THE 

PRINT"T IS THE 

PRINT 

PRINT" 

PRINT 

FOR M-l TO 12 

U-0 

FOR Y2-Y0 TO Yl 

Y-Y2-INT(Y2/10)*10 

E1-.5 

E2-.5 

U-U+( E(M,Y)*E1*. 0341 2 7+G(M , Y) *E2 )* 100000/ ( ( P( M , Y)+Q( M . Y) ) *A) 
NEXT Y2 



I !" 



T$(12,22)-"HEATING OIL" 
V$(17,32)-" OIL (THERMS X " 



YEARLY COST OF UTILITIES ($ DOLLARS )" 
,T$ ( 1, 1 1),T$(1 2,22 ),T$ (23,33);" COST/DEG . /DAY' 



AVE. BTU/(DEG*HR*SQ.FT.) . R - 1/U" 
AVERAGE MONTHLY TEMPERATURE OVER 30 YEARS" 

U R t» 



U-U/(24*(Y1-Y0+1)) 

PRINT M$(3*M-2,3*M) ; 

Ul-Ul+U 

NEXT M 
PRINT 

PRINT"THE AVERAGES 
PRINT" U 

PRINT" R 

PRINT" T 



" . IT . •• 

» u I 



FOR ";Y0;" 
";U1/12 
,12/U1 
";T/12 



TO 



Yl 



";1/U;" 



ARE 



";T(M) 



■ " 




The concept of a degree day is 
based on the fact that the fuel used to 
keep a building interior heated to 70 
degrees F is proportional to the num- 
ber of hours that the outside tem- 
perature is below 65 degrees F. Heat- 
ing-fuel suppliers developed this con- 
cept further to predict their custom- 
ers' needs and thereby keep their 
reserves adequate. 

For the purpose of our calculation, 
a degree day is the difference be- 
tween the daily mean temperature 
and 65 degrees F. It is always a posi- 
tive number. Each degree of mean 
temperature below 65 degrees F is 
one heating degree day. Weather sta- 
tions measure the hourly tempera- 
ture and calculate the average daily 
temperature by adding them together 
and dividing by 24. They use this 
mean temperature to determine the 
degree day value. 

A simpler method is sometimes 
employed which uses the median 
temperature instead of the mean. The 
median temperature of a day is the 
halfway point between the highest 
and lowest temperature existing dur- 
ing a 24-hour period. For example, if 
the highest temperature during the 
day were 42 degrees F and the lowest 
18 degrees F, the median would be 
(42+18)/2 = 30, and the degree day 
entry would be (65 -30) = 35. This 
concept is so important that all U.S. 
weather stations record daily, month- 
ly and seasonal totals. 

Since we are concerned with the 
consumption of heating fuel, days 
during the heating season when the 
mean temperature does not drop be- 
low 65 degrees F are ignored in the 
cumulative totals for heating degree 
days. In a similar manner, cooling 
degree days are those for which the 
mean temperature is above 65 de- 
grees F, and for which cooling energy 
loads are evaluated. 

The National Weather Service col- 
lects and records both heating and 
cooling degree days for most loca- 
tions in the U.S. This data for your 
local area, along with a 30-year aver- 
age for the monthly temperature, is 
available annually from the National 
Oceanic and Atmospheric Administra- 
tion (NOAA). The pamphlet is called 
the "Local Climatological Data An- 
nual Summary with Comparative 
Data," 1981 (specify your local area). 
They will also supply an additional 
pamphlet called "Heating and Cool- 
ing Degree Day Data, Environment 
Information Summaries CI 4." It's 
useful if you want to learn more 
Microcomputing, December 1981 63 





Listing continued. 








1040 


PRINT"AVE # HEATING DEGREE DAYS PER YEAR - " ; Q/ ( Y 1-Y0+1 ) 








1050 


PRINT"AVE # COOLING DEGREE DAYS PER YEAR - " ; P/ ( Yl-YO+1 ) 








8000 


PRINT 








8010 


PRINT 








8020 


PRINT"DATA KEY:" 








8030 


PRINT" + - SINGLE DATA POINT" 








8040 


PRINT" * - MULTIPLE DATA POINT" 








8050 


PRINT" # - MONTHLY AVERAGE" 








8060 


PRINT" < - BELOW RANGE" 








8070 


PRINT" > - ABOVE RANGE" 








8900 


FOR 1-0 TO 4 








8910 


IF 1-0 THEN W-50 








8920 


IF 1-1 THEN IF J-0 THEN W-5 








8922 


IF 1-1 THEN IF J-l THEN W-10 








8924 


IF I - 1 THEN IF JO - 1 THEN 9260 








8930 


IF 1-2 THEN W-250 








8940 


IF 1-3 THEN W-50 








8950 


IF 1-4 THEN W-2000 








8990 


FOR K-l TO 5 








8991 


PRINT 








8992 


NEXT K 








9000 


PRINT" ";T$(I*11 + 1,(I+1)*1D;" USED PER MONTH 








9010 


PRINT 








9020 


PRINT V$(I*16+1,(I+1)*16); 








9021 


PRINT W/5;") 75 100 150 200 250 


300" 






9030 


PRINT" ";X$ 








9040 


FOR M-l TO 12 








9050 


DO-0 








9060 


N-0 


it 






9070 


D$-" 








9075 


Z-l 








9080 


FOR Y2-YU TO Yl 








9081 


Y-Y2-INT(Y2/10)*10 








9089 


IF I - 4 THEN IF JO - 1 THEN 0-0 








9090 


IF 1-0 THEN E-E(M.Y) 








9100 


IF 1-1 THEN E-G(M.Y) 








9102 


IF 1-2 THEN E-G(M,Y)*29.302+E(M,Y) 








9104 


IF 1-3 THEN E-P(M,Y)+Q(M,Y) 








9105 


IF 1-4 THEN E-((E(M,Y)-L)*.034127+G(M,Y)-0)*100000/(P(M, 


Y)+Q(M,Y)) 






9106 


IF E-0 THEN 9180 








9107 


IF 1-1 THEN IF 0>-E THEN 0-E 








9108 


IF 1-0 THEN IF L>-E THEN L-E 








9110 


Dl-E/W 








9115 


IF DK1 THEN D$(l,l)-"<" 








9116 


IF DK1 THEN 9175 






9120 


D-INT(Dl) 


S~ > 






1 9125 


IF D>65 THEN D-65 


(Afore v 



about degree days. 

The above documents, and a 
number of other pamphlets, are 
available from the U.S. Department 
of Commerce, National Oceanic and 
Atmospheric Administration, Envi- 
ronmental Data and Information Ser- 
vice, National Climatic Center, Fed- 
eral Building, Ashville, NC 28801, for 
a $3 postage and handling charge. 
Very often the public library has 
these or equivalent publications 
which contain this information. The 
local TV station forecaster is also a 
good source. 

Although these temperatures-only 
techniques are satisfactory, they 
don't take into consideration the 
unique environmental conditions of 
your home, such as the number of 
hours of sunshine, wind speeds, 
house orientation and deciduous 
trees. However, these parameters are 
included in each month's evaluation 
simply by their presence in the utility 
bill, and thus in the effective R-value 
for the whole house. Equation 2 of 
Table 1 shows that if you know the 
total heat input (H) used by the house 
for a month (i.e., heating bill data) 
and the heating degree days for that 



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64 Microcomputing, December 1981 



month (Tin-Tout) along with the ex- 
posed area of the house, you can eval- 
uate the effective R-value. 

What the Program Does 

The program shown calculates the 
yearly cost of utilities and determines 
the energy cost per degree per day 
during that year. Next, the effective 
R-value for the house is evaluated for 
each month. 

A monthly value is used because 
environmental changes alter the heat 
balance. For example, during the 
spring and early fall most people 
open their windows for fresh air. 
This conductivity model clearly 
breaks down during this transition 
period from heating to air condition- 
ing or vice versa. 

The program then prints five 
graphs. Electricity consumed per 
month over the years is plotted first. 
Heating fuel followed by total energy 
used (after suitable energy units have 
been converted) is next. The total 
number of heating plus cooling 
degree days is represented for each 
month during the years covered. The 
last plot is the monthly energy ex- 
pended per degree per day. 



Listing continued. 



9126 

9127 

9130 

9140 

9150 

9160 

9170 

9175 

9180 

9190 

9200 

9205 

9210 

9220 

9225 

9240 

9250 

9260 

10000 

10001 

10010 

10990 

11000 

11001 

11002 

11003 

11004 

11005 

11006 

11007 

11008 

11009 

11010 

11011 

11012 

11013 

11014 

11015 

11016 

11990 

12000 

12001 

12002 



D$(D,D) 
9175 



i •• > " 



IF D-65 THEN 

IP D-65 THEN 

D0-D0+D1 

N-N+l 

IF Dl-D >-.5 THEN D-D+l 

IF D$(D,D)<>" " THEN D$(D,D)-"*" 

IF D$(D,D)-" " THEN D$ ( D , D) -"+" 

IF D>-Z THEN Z-D 

NEXT Y2 

D0-INT(D0/N) 

D$(D0,D0)-"#" 

PRINT" I" 

PRINT M$(3*M-2 



3*M) 



I" 
I" 



I";D$(1,Z) 



PRINT" 
PRINT" 
NEXT M 
PRINT" 
NEXT I 

END 

REM AVE 

DATA 32 

REM ELICTRICITY USAGE & MONTHLY COST 

DATA 0,0,0,0,440,14.59,800,22.6 7,740,21.31 
1650,4 2.74,2540,61.9 5,3180,76.4 3,28 30 



;X$ 



30 YR MONTHLY TEMP 



7,34.8,43.3,53.9,63.2,72.2,76.7,75.5,68.7,57.0,46.2,36.6 



850,26.98,1000,30.10,890,29.5 3,810,29 



,68 

63 

1660, 60. 83, 2460, 87. 41, 21 60, 80. 94, 2240, 84 

900,38.09,1060,41.93,920,37.69,960,37.60 

1560,60.83,2790 

850, 38. 65, 11 10, 46. 76, 990, 42. 56, 930 14 2.39,850, 39. 52! 980^42^7 3 
12 70,57.76,2460,102.2 7,2 7 30 



, 100 
3, 40. 7D,1080,46. 60, 990, 49. 56 
2110,104.37,2170,109 



DATA 
DATA 
DATA 
DATA 
DATA 
DATA 
DATA 
DATA 
DATA 
DATA 
DATA 
DATA 
DATA 
DATA 
DATA 
DATA 

REM NATURAL 
DATA 
41 



33, 18 30,46.85,86 0, 25. 10 
820,31 .82,910,34.30 
81,1230,50.13,780,34.01 



,820,33 



25,790, 



32.57 



107.84,2660,102.49,2140,87.61,1090,48.10,890,39.49 



76, 1180, 65. 99, 11 10, 51 .06,800,38.42 



1270,66.94 



970,46.74,980,48 



,820,43 



14,800,42.31 ,620,33 



54,2100,104.83,1060,57.29 



1080, 

940 

1140 



32,960,50.43,830,45 



58 



24,1760,98 



69,2140 



950,50.87, 

1110 

900 



54 
,. ...,,710,38 
86,740,40.51 ,800,42.69 

.54,820,46. 
63 
92. 

10,40.08 
62. 04, 2520, 134. 39, 1740, 95. 7 5, 2080, 11 5. 95, 1090164. 7 7. 890 



,50.78,1130 



51.81 



930,48 



117 
.98 



1210,67 



64.82 



,1270,68.82,2450, 



124 
1100,56.51 ,840,46.72 



02,2300,121.88 

1090,54.77,760,42 

94,1720,90.22,790,45 



00 



26 



24,770,43 



,880,47 



21,820,45.02 



,780,43.43 



,50.97 
GAS 



50.56 



USAGE & 



,0,0,0, 



0,0,0,0,95 



DATA 



5.5 



50, 14 



DATA 167.8,28.43 



12003DATA 52 
12004DATA136 



6,12 



71 ,26 



MONTHLY 
2,16.85 
.2,4.30,78.0, 14.29 
276.3,47.46,124.4 
.3,7.68,47.7, 11 .87 



COST 
,57.7,-3.25 



,18.2,5.07, 



96, 17 



49,205.8 



,22.68, 148 



8,27.17,74 



8.43 



4,32.22,221 



2,51 



14, 188 



6, 12 



9,44 



141 .4,34.56,71 .8 




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Microcomputing, December 1981 65 



Listing continued. 



12005 DATA 

12006DATA21 

12007 DATA 

12008DATA 2 

12009 DATA 

12010DATA25 

12011DATA27 

12012DATA21 

12013DATA29 

12014DATA21 

12015 DATA 



13000 
13010 
13020 
13030 
13040 
13050 
13060 
13070 
13080 
13090 
13100 
13110 
13120 
13130 
13140 
13150 
13160 



REM H 

DATA 

DATA 

DATA 

DATA 

DATA 

DATA 

DATA 

DATA 

DATA 

DATA 

DATA 

DATA 

DATA 

DATA 

DATA 

DATA 



38.8,11 

9.2,55. 

36.5,10 

49.4,64 

29.6,16 

0,78.81 

.6,16.5 

7,73.62 

.1 ,15.0 

2.9,84, 

29.3,16 

EATING 

935,0,8 

0,344,0 

830,0,8 

0,361 ,0 

818,0,7 

0,351 ,0 

1050,0, 

0,317,0 

1296,0, 

0,439,0 

1101 ,0, 

0,344,0 

984,0,1 

2,348,3 

1080,0, 

0,363,0 



.46,33. 

82,216. 

.64,32. 

.78,163 

.07,26. 

,246.2, 

7,42.7, 

,239.2, 

1,43,19 

195.7,7 

.94,39. 

AND COO 

54,0,51 

,376,24 

69,0,61 

,317,49 

20,0,70 

,404,50 

603,1,5 

,284,34 

790,0,4 

,401,9, 

1048,0, 

,413,33 

100,0,5 

,351,22 

766,0,7 

,293,24 



8,10. 

4,51. 

6,9.8 

.4,48 

4,15. 

78.02 

20.91 

80.37 

.11,3 

8.17, 

6,21 . 

LING 

1,0,3 

,173, 

3,4,3 

.130, 

2,0,4 

,85,1 

18,0, 

,114, 

69,10 

329,2 

715,0 

,182, 

20,15 

,U5, 

12,0, 

,208, 



18,35. 

75,137 

3,30.4 

.82,10 

24,32. 

,103.6 

,30.5, 

,108.3 

5.2,18 

102.5, 

25,35. 

DEGREE 

65,15, 

221 ,19 

09,24, 

303,8, 

36,4,6 

56,27, 

293,58 

377,9, 

,245,3 

78,7,4 

,318,0 

280,12 

,354,4 

311,28 

364,0, 

96,36, 



7,10. 
.6,35 
,9.29 
8.4,3 
5,17. 
,39.2 
17.47 
,41.0 
.39,6 
45.08 
6,20. 
DAYS 
191,2 
,524, 
148,5 
509,1 
6,112 
397,1 
,133, 
716,0 
7,62, 
76,10 
,141, 
,483, 
,75,7 
,425, 
134,2 
571,2 



64,41.6,11.92,34.3,10.19,141.4,35.93 

.79,110.3,27,7 2,19.20,40.6,11.28 

,33.4,10.30,84.9,22.79,200.4,51.37 

5.4,55,22.03,30.7,16.02,52.8,21.76 

49,61.7,25.69,154.8,51.43,205.4,64 

3,40.5,20.61,32.6,17.99,49.2,22.60 

,56,24.88,123.6,44.57,154.1,53.37 

2,44.5,21.03,27.7,15.38,49.9,21.44 

3.9,28.49,120.3,48.11,156.5,60.26 

,39.5,21.35,33.5,18.91,43.6,22.79 

39,55.8,28.38,14 2.1,63.08,0,0 



9,1,263 

0,852,0 

7,14,126 

1,759,0 

,2,252 

0,853,0 

51,11,315 

,1001,0 

124,18,217 

,904,0 

63,9,260 

00,763,0 

2,6,193 

1,757,0 

4,2,278 

0,652,0 



D(M) = yearly average of month's electricity usage (KWH) 
M(M) = yearly average of month's heating fuel (Therm) 
T(M) = 30 year average monthly temperature 
A = exterior area of house in square feet 
P(M,Y) = heating degree days for a given month of a year 
Q(M,Y) = cooling degree days for a given month of a year 
E(M,Y) = electrical energy (KWH) for a given month of a year 
F(M,Y) = cost of electricity in dollars for one month 

G(M, Y) = heating fuel (gal. if heating oil, Therms if natural gas) for a given month of a year 
H(M,Y) = cost of heating fuel for a given month of a year in dollars 
Y0 = starting year 
Yl = ending year 

El = air conditioner efficiency (assumed 50 percent) 
E2 = furnace efficiency (assumed 50 percent) 
U = number of BTU/(degree *hour* square foot) 
R= l/U = effective Rvalue of house 
W = graph scale multiplication factor 

Table 2. Variable identities. 



Sample run. 



*RUN 



DO 
DO 



YOU 
YOU 



HAVE ELECTRIC HEATING FOR 
HAVE OIL HEATING FOR YOUR 



YOUR HOME? 
HOME? (YES 



(YES OR N0)?N0 
OR N0)?N0 



YEARLY COST OF UTILITIES ($ DOLLARS ) 



YEAR 

1973 
1974 
1975 
1976 
1977 
1978 
1979 
1980 



ELECTRICITY 

406.94999 
591 .59999 
668.04999 
670.91999 
742 .85999 
788.21999 
730.44999 
809.96999 



NATURAL GAS 

94.869999 

250.259999 

282.87999 

315.05999 

398.72999 

435.02999 

442.22999 

420.33999 



TOT. ENERGY COST/DEG . /DAY 



501.81999 

841.85999 
950.92999 
985.97999 
1141 .58999 
1223.24999 
1172.67999 
1230.30999 



.088084956 

.154725233 
.17464279 
.167541205 
.186503838 
.19841849 
.205157451 
.218799572 



U IS THE AVE. BTU/(DEG*HR*SQ.FT.) . R - l/U 

T IS THE AVERAGE MONTHLY TEMPERATURE OVER 30 YEARS 



U 

JAN .128782699 

FEB .167665786 

MAR .142423688 

APR .174795641 

MAY .269589761 

JUN .243802851 

JLY .194719424 



7.7650181 

5.964246 

7.0213038 

5.7209664 

3.7093396 

4.1016747 

5.1355944 



32.699999 
34.8 
43.3 

53.899999 
63.199999 
72.199999 
76.699999 




More 



These values are useful if you are 
contemplating adding more insula- 
tion, or have just done so and wish to 
determine the cost-effectiveness of 
your work. The cost per degree per 
day shows the average of how much 
you can save each day by adjusting 
your thermostat one degree accord- 
ing to the season. The important 
point here is that the results reflect 
the way you actually live in your 
house. 

How It Works 

The program is written in a version 
of BASIC that can be easily adapted 
to a variety of systems. In the BASIC 
version used here, the RESTORE 
statement must precede any data 
statement to initialize the pointers. 
Most versions in use today do not 
require this first initialization, and 
therefore it can be deleted from those 
programs. 

Some constants unique to your 
house are required in the program. In 
line 142 the exterior surface area, A, 
is needed. The ground floor or base- 
ment floor area is not included unless 
there is a crawl space under the 
house. This area includes all walls 
and ceilings which face the exterior 
of the house; i.e., the surface area 
through which the heat flows to the 
outside. 

Lines 148 and 149 contain the be- 
ginning and ending years for which 
the data is available. For example, if 
the data was only for 1980, then Yl 
and Y0 would be the same, because 
the data is recorded from January to 
December. Lines 150 through 180 
contain the string data necessary for 
the graphics plots. The key variables 
are identified in Table 2. 

Next, the data statements are read 
in the proper format. The program 
expects first to read the 30-year 
monthly average temperatures, 
T(M), in lines 218 to 240. This is an 
optional feature which can be 
dropped since it serves only as a 
guideline in the printout at lines 941, 
943, 970 and 1030. It is not used in 
the calculations, but was included 
here because it was available from 
the U.S. Weather Service. The data 
statements starting at Vine 10010 will 
be different for different areas around 
the country. 

Data from your electric utility bill 
is then entered in the data statements 
beginning with line 11000. Monthly 
kilowatt hours (KWH) and cost are 
entered as pairs, starting with 
January of the first year. If this data is 



66 Microcomputing, December 1981 



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not available, enter zeros for the 
KWH and cost for each missing 
month. Don't skip any months! The 
year is concluded with December's 
values. 

The heating utilities (natural gas or 
heating oil) are entered in the same 
way starting with line 12000. The 
units for natural gas are therms and 
the units for heating oil are gallons. A 
therm is 100,000 BTU, and is the ba- 
sic unit on most bills. The electricity 
and heating utility data must begin 
and end with the same year. The pro- 
gram will select the proper conver- 
sion constants depending on whether 
you use oil or natural gas for heating. 
This is determined by lines 300 to 
450. 

The program asks if you use elec- 
tricity, gas or oil as the source for 
your home heating. If electric heat is 
used, then lines 382 through 484 are 
skipped, and the gas or oil data 
statements are not used. If oil heat is 
selected, the data statements begin- 
ning with line 12000 must show 
monthly gallons and cost expended. 
If neither electric nor oil heat is 
selected, the program defaults to 
natural gas as the heating fuel. The 




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Sample run continued. 



AUG 
SEP 
OCT 
NOV 
DEC 

THE 



AVE 
AVE 



.202107243 

.36261267 

.223375197 

.157076413 

.139170444 



AVERAGES 
U 
R 
T 



FOR 1973 TO 

- .20051015 

- 4.9872786 

- 55.066666 



4.9478681 
2.7577635 
4.4767727 
6.3663281 
7. 1854337 

1980 ARE: 



75.5 
68.699999 
57 

46. 199999 
36.6 



# 
I 



HEATING 
COOLING 



DEGREE 
DEGREE 



DAYS 
DAYS 



PER 
PER 



YEAR 
YEAR 



4526.875 
1234.75 



DATA KEY: 



+ - SINGLE DATA POINT 

* - MULTIPLE DATA POINT 

# - MONTHLY AVERAGE 
< - BELOW RANGE 

> - ABOVE RANGE 



ELEC 



ELECTRICITY USED PER MONTH 
(KWH X 10) 75 100 



15 
I 



200 

I 1 



250 

I 1 



300 

I 1 



JAN 



FEB 



MAR 



APR 



MAY 



JUN 



JLY 



AUG 



SEP 



OCT 



NOV 



DEC 



! 1 1 1 1 1 1 1 1 1 1 1 — 

*#* + 



+ #** 



#++* + 



*# + 



+ +#* + + 



*+ *# + * 



+ # *++ + 



* #+ + + 



#* + ++ 



+ +*#++ 



+ #+* 



*#* 



I 1 1 1 1 1 1 1 1 1 1 1 1 I 



NATURAL GAS USED PER MONTH 



GAS 

JAN 

FEB 
MAR 
APR 



MAY 



THERMS X 1) 75 100 150 
! 1 1 1 1 1-- 



200 
— I — 



250 
._!-■ 



300 
— I— 



# * + 



+ +# ++ 



** #+ + 



*+ + # 



** # *+ + 



+ + 




68 Microcomputing, December 1981 





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RS202 TRS-80 Monitor or TV set 84 

RS204 TRS-80 Model III 129 

RS205 Radio Shack Color Computer 89 

AT301 Atari Computer & Accessories 109 

P401 Paper Tiger 440/445/460 99 

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Microcomputing, December 1981 69 



Sample run continued. 



JUN 



JLY 



AUG 



SEP 



OCT 



NOV 



DEC 



*+#*++ 



*#* + 



+ *#* + * 



**# + 



+ ++#+*++ 



+ + 



+# ++ + + 



+ * # + +* 



| i I I I I I I I I 1 I 1 1 



TOT. ENERGY USED PER MONTH 
ENERGY (KWH X 50) 75 100 



150 
I 



JAN 



FEB 



200 

I 1- 



! i 1 I I I I 

+ + #+* ++ 

+ + # + ++ + 



250 

I 1- 



300 

I 1 




More 



data statements must then contain 
the monthly therms and cost. 

You must be sure when you enter 
the energy values from your utility 
bills that they correspond to the 
month the energy was used and not 
when the bill came due. This must be 
done to correlate energy consump- 
tion with the degree days for each 
month. Otherwise, there will be a 
skew in the graphs. 

The final data needed is the heating 
and cooling degree days in each year 
for which utility bills are known. 
Starting with January, the heating 
and cooling degree days are entered 
as monthly pairs at line 13000. Enter 
heating then cooling for each month 
in the data statements (e.g., Jan. 1973: 

935, 0). 

M and Y are the month and year in- 
dices. The function in line 310 is used 
to reduce the year to a single digit for 
use in the FOR loop and in the two- 
dimensional arrays. 

El and E2 in lines 954 and 955 are 
the efficiencies of the air conditioner 
and furnace. I assigned a reasonable 
approximation of 50 percent to each. 
If you have a more accurate value, 
use it. In lines 8910 and 8950 the 



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70 Microcomputing, December 1981 



OSI 



TRS-80 



COLOR-80 



OSI 



GALAXIAN - 4K - One of the fastest and finest 
arcade games ever written for the OSI, this one 
features rows of hard-hitting evasive dogfighting 
aliens thirsty for your blood. For those who 
loved (and tired of) Alien Invaders. Specify 
system - A bargain at $9.95 OSI 



LABYRINTH - 8K - This has a display back- 
ground similar to MINOS as the action takes 
place in a realistic maze seen from ground level. 
This is, however, a real time monster hunt as you 
track down and shoot mobile monsters on foot. 
Checking out and testing this one was the most 
fun I've had in years! - $13.95. OSI 



THE AARDVARK JOURNAL 

FOR OSI USERS - This is a bi-monthly 
tutorial journal running only articles about OSI 
systems. Every issue contains programs custom- 
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the system, and reviews of OSI related products. 
In the last two years we have run articles like 
these! 

1) A tutorial on Machine Code for BASIC 
programmers. 

2) Complete listings of two word processors 
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3) Moving the Directory off track 12. 

4) Listings for 20 game programs for the OSI. 

5) How to write high speed BASIC — and 
lots more — 

Vol. 1 (1980) 6 back issues - $9.00 

Vol. 2 (1981) 4 back issues and subscription for 
2 additional issues - $9.00. 

ADVENTURES!!! 

For OSI, TRS-80, and COLOR-80. These 
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Adventures require 8K on an OSI and 16K on 
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ESCAPE FROM MARS (by Rodger Olsen) 
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TREK ADVENTURE (by Bob Retelle) 
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DEATH SHIP (by Rodger Olsen) 
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OSI NEW-NEW-NEW OSI 

TINY COMPILER 

The easy way to speed in your programs. The 
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TINY COMPILER is written in Basic. It can 
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TINY COMPILER - $19.95 on tape or disk OSI 

SUPERDISK II 

This disk contains a new BEX EC* that boots 
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SUPERDISK II $29.95 (5 1 /4") OSI 

BARE BOARDS FOR OSI C1P 

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SUPPORT ROMS FOR BASIC IN ROM MA- 
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Has one character command to switch model 
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of additional chip. C1P requires only a jumper 
change. — $39.95 

C1E/C2E similar to above but with extended 
machine code monitor. — $59.95 OSI 



ARCADE GAMES FOR OSI, COLOR-80 AND 
TRS-80 (8K OSI, 16K TRS-80 AND COLOR-80) 

TIMETREK - A REAL TIME, REAL GRAPHICS 
STARTRECK. See your torpedoes hit and watch 
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STAR FIGHTER - This one man space war game 
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cockpit window, a real time working instrument 
panel, and your wits. Another real time goody. 
$9.95 

BATTLEFLEET - This grown up version of Bat- 
tleship is the toughest thinking game available on 
OSI or 80 computers. There is no luck involved 
as you seek out the computers hidden fleet. A 
topographical toughie. $9.95 

QUEST - A NEW IDEA IN ADVENTURE 
GAMES! Different from all the others, Quest is 
played on a computer generated mape of Alesia. 
Your job is to gather men and supplies by comb- 
bat, bargaining, exploration of ruins and temples 
and outright banditry. When your force is strong 
enough, you attack the Citadel of Moorlock in a 
life or death battle to the finish. Playable in 2 to 
5 hours, this one is different every time. 
16K COLOR-80 OR TRS-80 ONLY. $14.95 




Please specify system on all orders 

This is only a partial listing of what we have to offer. We offer over 120 games, ROMS, and data sheets for OSI systems 
and many games and utilities for COLOR-80 and TRS-80. Send $1.00 for our catalog. 



OSI 



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Microcomputing, December 1981 71 



scale factor W is specified for the five 
graphs. You may want to raise or 
lower these values, depending on the 



maximum utility value for any given 
month. The scale marking for each 
month is graduated from to 325. W 



Sample run continued. 
mar i + 



+#++ + 



APR 



MAY 



JUN 



JLY 



AUG 



SEP 



OCT 



NOV 



DEC 



+ * +# + ++ 



** # * + 



#* + 



+ + + #* + * 



*#** 



+ + *# + + 



+ *#* 



+ + +#++++ 



+ # ++* 



; i i I 1 I I 1 1 I 1 I I 1 




determines the multiplication factor 
that is used with this scale. In the 
sample run for the total energy used 
in the month of January, a data point 
occurs at the scale value of 100. The 
scale factor is 50 for this graph, so the 
data point represents total energy 
consumption of 5000 KWH. 

Index I steps through the five 
graphs and determines the proper 
string variable lengths to be used m 
each plot. In line 9105 the values L 
and O are the respective minimum 
values for electricity and heating 
fuel. They are assumed to be the 
monthly operating conditions for the 
house without heating or cooling 
energy loads. L and O are arbitrarily 
set to a high value (i.e., 10,000). Lines 
9107 and 9108 then choose the min- 
imum nonzero values for L and O, 
respectively, from the data. 

There is some question as to the 
merit of this assumption. The con- 
cept of the degree day is based on the 
fact that the inside temperature is as- 
sumed to be 70 degrees F, while de- 
gree days are determined based on 65 
degrees F exterior temperature. Daily 
energy consumption, excluding 
heating or cooling, produces heat 



LU 

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cr 



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3 
Q. 

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o 
o 



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CO 



CO 



RACFT SORTS - RACET UTILITIES - RACET computes - RACET SORTS - RACET UTILITIES - RACET computes - RACET SORTS - RACET UTILITIES - RACET computes - 



O 

< 
cr 



</) 

t- 
cr 
O 

CO 

»- 

o 

< 
cr 



(0 

B 

3 
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FIELD PROVEN!! 

10 MEGABYTES and MORE for the TRS-80* Model II 

plus SHARED ACCESS to HARD DISK DRIVE 

Hard/Soft Disk System (HSDS) Software allows access as single drive. You can 
have that 10 Megabyte continuous file - that 50,000 name maillist or inventory! Or 
a directory with 1000 entries! All completely compatible with TRSD0S 2.0 BASIC. 
You can mix floppy and hard disk drives. Includes special utilities including HPURGE, 
DCS Directory Catalog System, HZAP Hard Disk Superzap, and many special 
formatting options. Three to eight times faster than floppy! RACET quality. 

HARD DISK DRIVE ft CONTROLLER $5995. Second User $595. 

HSDS Software $400. (Note: HSDS now also available for C0RVUS drives!!) 

INFINITE BASIC (Mod I & III Tape or Disk) Mod I $50.00, Mod III $60.00 

Extends Level II BASIC with complete MATRIX functions and 50 more string 
functions. Includes RACET machine language sorts! Sort 1000 elements in 9 
seconds! ! Select only functions you want to optimize memory usage. 

INFINITE BUSINESS (Requires Infinite BASIC) Mod I ft III $30.00 

Complete printer pagination controls — auto headers, footers, page numoers. 
Packed decimal arithmetic — 127 digit accuracy + , -, *, /. Binary search 
of sorted and un sorted arrays. Hash codes. 

BASIC CROSS REFERENCE UTILITY (Mod II 64K) $50.00 

SEEK and FIND functions for Variables, Line Numbers, Strings, Keywords. 'All' 
options available for line numbers and variables. Load from BASIC — Call with 
'CTRL'R Output to screen or printer! ^^^ 

DSM Mod I $75.00, Mod II $150.00, Mod III $90.00 

Disk Sort/Merge for RANDOM files. All machine language stand-alone package for 
sorting speed. Establish sort specification in simple BASIC command File. Execute 
from DOS. Only operator action to sort is to change diskettes when requested! 
Handles multiple diskette files! Super fast sort times — improved disk I/O times 
make this the fastest Disk Sort/Merge available on your TRS. 

(Mod I Min 32K 2-drive system. Mod II 64K 1-drive. Mod III 32K 1 -drive) 

GSF (Mod I & III Tape or Disk - Specify Memory Size) 
Mod I $25; Mod II $50; Mod III $30 

Generalized Subroutine Facilities. The STANDARD against which all other sorts are 
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Multi-key multi-variable and multi-key character string. Zero and move arrays. 
Mod II includes USR PEEKS and POKES. Includes sample programs 



DISCAT (32K 1 -drive Min) Mod I, III $50.00 

This comprehensive Diskette Cataloguing/Indexing utility allows the user to keep 
track of thousands of programs in a categorized library. Machine language program 
works with all TRSD0S and NEWD0S versions. Files include program names and 
extensions, program length, diskette numbers, front and back, and diskette free space. 

KFS-80 (1-drive 32K Min — Mod II 64K) Mod I, III $100.00; Mod II $175.00 

The keyed file system provides keyed and sequential access to multiple files. Provides 
the programmer with a powerful disk handling facility for development of data base 
applications. Binary tree index system provides rapid access to file records. 

MAILLIST (1-drive 32K Min Mod II 64K) Mod I, III $75.00; Mod II $150.00 

This ISAM-based maillist minimizes disk access times. Four keys — no separate 
sorting. Supports 9-digit zip code and 3-digit state code. Up to 30 attributes. Mask 
and query selection. Record access times under 4 seconds!! 

C0MPR0C (Mod I & Mod III — Disk only) Mod I $20; Mod III $30 

Command Processor. Auto your disk to perform any sequence of instructions that 
you can give from the keyboard. DIR, FREE, pause, wait for user input, BASIC, No. 
of FILES and MEM SIZE, RUN program, respond to input statements, BREAK, 
return to DOS, etc. Includes lowercase driver software, debounce and screenprint! 

UTILITY PACKAGE (Mod II 64K) $150.00 

Important enhancements to the Mod II. The file recovery capabilities alone will pay 
for the package in even one application! Fully documented in 124 page manual! 
XHIT, XGAT, XC0PY and SUPERZAP are used to reconstruct or recover date from 
bad diskettes! XC0PY provides multi-file copies, Wild-card' mask select, absolute 
sector mode and other features. SUPERZAP allows examine /change any sector on 
diskette include track-0, and absolute disk backup/copy with I/O recovery. DCS 
builds consolidated directories from multiple diskettes into a single display or 
listing sorted by disk name or file name plus more. Change Disk ID with D\SK\0. 
XCREATE preallocates files and sets 'LOF' to end to speed disk accesses. DEBUGII 
adds single step, trace, subroutine calling, program looping, dynamic disassembly 
and more!! 

DEVELOPMENT PACKAGE (Mod II 64K) $125.00 

Includes RACET machine language SUPERZAP, Apparat Disassembler, and Model 
II interface to the Microsoft 'Editor Assembler Plus' software package including 
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CHECK, VISA, M/C. COD. PURCHASE ORDER 
TELEPHONE ORDERS ACCEPTED (714) 997-4950 

•TRS-80 IS A REGISTERED TRADEMARK 
OF TANDY CORPORATION 



x 
> 
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a> 

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30 

> 



re 
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30 

> 
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m 

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CO 
O 
30 
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3D 

> 



ET* RACET computes -Eg 

1330 N. GLASSELL, SUITE M, 

ORANGE. CA 92667 ^ 101 



CO 



3D 

> 



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CD 
09 



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" ww •— *- — ■ r r • Uh 1ANUYUUHPUHAIIUN 

RACET SORTS - RACET UTILITIES - RACET computes - r^E^Oj^S^lA^T^LrmS^R^ET^mpute^ RACE^ORTS ^A^T^L^S^R^ET^onnputes^- 



72 Microcomputing, December 1981 



from appliances or lighting along 
with the solar energy absorbed. 

If your version of BASIC cannot 
handle the double IF statements in 
line 8920, 8922, 9107 or 9108, then 
you can divide it into two or more 
lines each. 

The graphs are constructed using 
the string variable D$, which is ini- 
tially set to blanks for each line. Posi- 
tions in the string are then assigned in 
lines 9150 through 9200 for the cor- 
responding data points. This tech- 
nique is often used with Teletype- 
based printers. This type of string 
handling lends itself nicely to this ap- 
proach, but other string-handling sys- 
tems can be modified to accomplish 
the same effect. See, for example, 
"Strings and Things: BASIC Conver- 
sion Techniques," by Richard Roth, 
Kilobaud Microcomputing, May 1978, 
pp. 94-98. 

Conclusions 

Although this is a rough cut at the 
energy efficiency of a house, it is re- 
markably accurate during peak heat- 
ing and cooling months. There are a 
number of excellent pamphlets, bro- 



Sample run continued. 



DEGREE DAYS USED PER MONTH 



HEAT+C00L(D.D.X 10) 
I 1- 



75 
I- 



100 
I- 



150 
I 



200 
I- 



250 
I 



300 

I 1 



JAN 



FEB 



MAR 



APR 



MAY 



JUN 



JLY 



AUG 



SEP 



OCT 



1 i ! ! j ! ! j x j 

++ + # + * + 



+ ++#* ++ 



*# + * 



*#++ 



#* 



+ #*++ 



+ # + 



*#* 



*#+ + 



++#*++ 




TM 



PONY EXPRESS: software for an electronic mail network 

Hook up your office and home micro-computers . . . Connect your branch offices . . . Create a micro- 
computer network with friends, clients or associates . . . All you need is your present telephone and 



The Pony Express 



TM 



>r 



The Pony Express lets two micro-computers exchange any information you choose letter, a con- 
tract, graphics, VisiCalc* models, even other programs over regular telephone lines. It is custom- 
fit, fully compatible with your software. With the unique on-line manual and guided walkthru features, 
a computer novice can master Pony the first time he uses it. Pony's security system, and time and 
money saving features make it ideal for business applications. Home users will find it equally practical. 

The Pony Express is a package that is: 



designed by management consultants, and field- 
tested in business and professional applications 

easy to use, requiring only plain English. About the 
most complicated computerese is the term "file." 

easy to learn, displaying WALKTHRU comments and 
reminders while you run it. 

superbly documented, with a computerized manual 
that puts you a touch-of-a-button away from all you 
need to know. 



economical of your time; unattended it handles a 
diskful of data through its INBASKET and OUT- 
BASKET features. 

secure and discrete, it lets an operator run the system 
"blind", never laying eyes on sensitive information. 

reliable, it automatically corrects transmission errors 
to ensure that what you send is what gets there. 

mindful of your phone bills, the TOLL-SAVER and 
SUPER TOLL-SAVER features cut transmission time 
up to 70^r. 



TM 



PONY EXPRESS ' M : "thoughtful software'" M from the Philadelphia Consulting Group, Inc. ^ ioe 



Available for Radio Shack* 32 K Model III 
with 2 disks. Most features work with 1 
disk. Modem and RS232 communications 
interface required. INQUIRE ABOUT FU- 
TURE AVAILABILITY FOR OTHER 
COMPUTERS. Dealer and OEM inquiries 
invited. 



Software for 2-member network: $140 
Each additional member: 40 

Manual only (fully credited toward 
purchase) 15 

* Radio Shack and TRSDOS are trademarks 
of Tandy Corporation. DOSPLUS is a 
trademark of Micro Systems Software, Inc. 
VisiCalc is a trademark of Personal Soft- 
ware, Inc. 



Visa and Master Card orders: 
Call 1-800-227-1617, EXTENSION 203. 

In California Call 1-800-772-3545. 
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19096. 



■See List of Advertisers on page 210 



Microcomputing, December 1981 73 



Sample run continued. 



NOV 



DEC 



++# + + 



+ *#*+ + 



| J i i i ! J i i J J i i 1 



EGY/DEG.DAY USED PER MONTH 

( BTU/DEG.DAY X 400) 75 100 150 

I I 1 I 1 I I 



200 250 300 
I 1 1 1 1 1 



JAN 



FEB 



MAR 



APR 



MAY 



JUN 



JLY 



AUG 



SEP 



OCT 



NOV 



DEC 



+ #+* 



*+# * + 



* #* * 



:< +* + # * 



+ *+ # ++* 



++ ++#+++ 



+ * #+ ** 



+++# + + 



+ + + * # + + 



+ +++# + 



+++ # ++++ 



+ #+*+ 



; J i I J I I I I I I I I I 



chures and books for the layman 
on home insulation calculations (see 
references). Using one of these for 
the house illustrated in the sample 
run, an overall R-value of 7.4 was de- 
termined. As you can see, this agrees 
with the heating months' Rvalue as 
determined from the utility bills and 
degree day data. 

The final graph is really a measure 
of the accuracy of the conductive mo- 
del. It shows that the average energy 
consumed for every degree different 
from the interior temperature is 
relatively constant during the year. 
This is the chief reason why heating 
fuel suppliers use the degree day con- 
cept in their business. 

If you're interested in acquiring a 
more detailed and accurate energy 
analysis for your house, there is an 
excellent booklet published by the 
Superintendent of Documents, U.S. 
Government Printing Office, Wash- 
ington, DC, 20402, for $1.35. It is 
called "Retrofitting Existing Housing 
for Energy Conservation: An Eco- 
nomic Analysis,' by Stephen R. 
Petersen of the National Bureau of 
Standards. He sets up the variables 
and a flowchart for a BASIC program. 
Order S.D. Catalog No. CI 3.29:2/64. ■ 



References 

Money-Saving Guide to Energy in the 
Home by Consumer Reports. Double- 
day and Co., Garden City, NY, 1978. 
How to Do Your Own Home Insulation 
by L. Donald Meyers. Harper and 
Row, New York, 1978. 



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TRS80 is a trademark ol the Radio Shack Division ol Tandy Corporation 



Designed for your . . . 

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74 Microcomputing, December 1981 



THE ORIGINAL MAGAZINE FOR 
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TRS 80™ IS A TRADEMARK OF TANDY CORP. 



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• DISK FILES 

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• DOS COMMANDS IN LEVEL II 

• PROBABILITY CURVE GENERATOR 

• CALCULATOR SIMULATIONS 

• THE MEGABYTE GAP 

• STOCKS AND BONDS 

• BUDGET ANALYSIS (FOR BUSINESS AND HOME) 

• NEWDOS/80 REVIEW 

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'See List of Advertisers on page 210 



Microcomputing, December 1981 75 



Be the first one on your block to interface a Teletype to your Sorcerer. Whether or not you have a printer, 

you'll find the accompanying software useful 



Printing Wizardry 
For Your Sorcerer 



By Ernest E. Bergmann 



When I found that most printers 
cost almost as much as my Exi- 
dy Sorcerer, I bought an inexpensive 
old Teletype Model 33. The hard- 
ware, although not elegant, works 
(see schematic). And the software is 
useful even without a printer, letting 
you stop or slow the listing whenever 
you want. 

The software for the interface had 
to meet several criteria. 

First, it had to be a patch to my I/O 
drivers so that it would automatically 
be usable with BASIC or the develop- 
ment ROM Pac. 

Second, it had to be small enough 
to fit in RAM below 100H. 

Third, it needed to use the control 
code conventions of CP/M; control-P 
would turn on and off the printing 
and control-S would halt output. An- 
other key would let the output 
resume. 

Fourth, because the character set of 
the Model 33 printer is limited, all 
lowercase letters routed to the printer 
had to be converted to uppercase. 

Finally, the program had to be clear 
and easy to modify for future needs, 
such as other printers and baud rates. 

The I/O Patches 

It is good programming to provide 
patch points for all of the I/O drivers, 
so that you can make changes with- 
out too much fuss. 

You need to replace the original 

Address correspondence to Ernest E. Bergmann, 
Physics Department, Building 16, Lehigh Univer- 
sity, Bethlehem, PA 18015. 

76 Microcomputing, December 1981 



calls to the Sorcerer's keyboard with 
calls to your substitute routine, which 
behaves just like the original routine 
except that it filters out control-P for 
special action. 

Also, you must replace the Sorcer- 
er's original video routine with the 
new output routine. This new routine 
not only displays output on the video 
screen, but also drives the printer, 
and checks the keyboard for a con- 
trol-S and takes the appropriate ac- 
tion when one occurs. 

To substitute in our two I/O rou- 
tines (CHIN and CHOUT) when us- 
ing the Sorcerer's monitor, you can 
use the commands >SET 1 = 50 and 
>SET = 5B. Or, to make life a bit 
easier, you can execute IOINIT (loca- 
tion 2 AH in RAM, line 30 in the list- 
ing). This initialization routine calcu- 
lates the locations in the monitor 
work area (MWA), where the ad- 
dresses for CHIN and CHOUT must 
be placed, and then performs the two 
patches. 

The Initialization Routine 

IOINIT works properly with ma- 
chine code programs that call the 
monitor's RECEVE input routine at 
E009H and the monitor's SEND out- 
put routine at 0E00CH. These re- 
quirements are innocuous enough for 
assembly-language user programs, 
and are met by the BASIC ROM PAC. 

Also, a little detective work estab- 
lishes that everything is all right in 
the Development ROM PAC; the I/O 
drivers, :SK and :SK, which are de- 
scribed on page 17 of the user's man- 



ual as the Sorcerer Keyboard and Sor- 
cerer Video Screen, are actually using 
the monitor's RECEVE and SEND. 
You must beware of one potential 
problem: the Development PAC must 
be able to place a jump instruction at 
the RST 7 location, 38H, which is in 
the area where the IOINIT routine re- 
sides. After a little fitting with a rela- 
tive jump instruction, you free up 
these critical three bytes. 

This is how you can find (and the 
way IOINIT finds) the proper loca- 
tion for the patches: the memory lo- 
cations, 0F000H and 0F001H contain 
the value of the highest RAM ad- 
dress, which, of course, depends 
upon the particular computer config- 
uration. By subtracting 6EH from (by 
adding 0FF92H to) this address you 
find the base address of the monitor 
work area (MWA). According to the 
Exidy documentation, MWA + 3FH 
and MWA + 40H should contain the 
address of the routine used by SEND, 
and MWA + 41H and MWA + 42H 
contain the address used by RECEVE. 

Once the IOINIT routine performs 
its patches, it is no longer needed and 
can be overwritten to make use of all 
the RST locations. 

The Input Routine 

You require of the character input 
routine, CHIN, that if no key is 
pressed, it should return immediate- 
ly with the Z flag set. If a key is 
pressed, the original KEYBRD rou- 
tine waits until the key is released, 
and then returns with the ASCII val- 
ue of the character in the A register 



TO EXIDY PARALLEL PORT 



*I5> 



I I 



#7> 



I I 



14 



I I 

\ \ 
I I 



13 



♦ 5V 



^7 



II 



4^ 



10 





7404 



ri>n H>n rC>n 



#i> 



i i 



T-r 



S6ft 



-» ■»■ 



hP) l0 



CURRENT 
LOOP 



40 



Schematic of circuit used to convert the TTI X signals from one of the pins of the computer's output port to 
the active 60 mA (and 75 VJ loop of the particular ASR33 unit the author has. 



and the Z flag reset. 

Similarly, CHIN would return 
when the key is released, except 
when a control-P has been entered. If 
this particular character has been 
typed, CHIN complements the vari- 
able STATE (used to control output 
to the printer) and CHIN reenters it- 
self to get whatever follows the con- 
trol-P. Thus, the calling program nev- 
er is aware that a control-P was ever 
entered from the keyboard. The 
CHIN routine resides in lines 56-70. 

The Output Routine 

Let's turn our attention now to the 
character output routine, CHOUT. 
On entry (line 77 in the listing), 
CHOUT calls CTRLS, a routine which 
looks for a control-S from the key- 
board (which will be described later). 

Next (starting in line 78), CHOUT 
checks the value of STATE to see 
whether the printer should be sent 
any output. If STATE is zero, no ac- 
tion is taken and control is passed to 
the Sorcerer monitor's VIDEO at 
0E01BH. Otherwise, CHOUT must 
send appropriate signals to the print- 
er. The PRINT routine gets the char- 
acter to the "primitive" typewriter 
output routine, FTYO, and then exits 
to the Sorcerer's VIDEO; PRINT en- 
sures that the contents or registers 
are saved. 

PTYO (starting at line 90) does 
most of the actual work, but it is not 
concerned with protecting the origi- 
nal contents of registers (that was 
PRINT'S job). Since the Model 33 
printer cannot produce symbols cor- 
responding to ASCII codes higher 
than the character z, it doesn't try (it 
simply returns). The ASCII character 
60H ('J, just before a, looks almost 
like a single quote or apostrophe, 
ASCII 27H ('); you make the printer 
print the substitute. Between 60H 
and z + 1 you have the lowercase al- 



phabet; since the printer has only up- 
percase type, you subtract 20H to 
convert it to uppercase. 

You are almost ready to send the 
character to the printer, except that 
there are three control codes to which 
the printer should respond that re- 
quire special handling. The line feed 
and carriage return characters take 
extra time to perform. The routines 
LF and CR provide extra time, which 
is adjusted by the value of WAIT; I 
picked a value which appears to 
work. It probably depends upon the 
lubrication in the printer mechanism, 
so you can change the value of WAIT 
easily. 

A popular control code with the Ex- 
idy is control-L, the form feed charac- 



ter, which clears the screen. To keep 
things simple, I have implemented a 
reasonable facsimile with a carriage 
return followed by a number (FFSIZE) 
of line feeds. 

After filtering out these three spe- 
cial control codes, we continue down 
to UART (line 112), which transmits 
the character to the printer. 

The Software UART 

To operate at 110 baud, I imple- 
mented a software UART. The hard- 
ware UART of the Sorcerer, which is 
already overused in the cassette and 
RS-232 interface, only operates at 300 
and 1200 baud. The UART must send 
out a serial stream of binary data. At 
110 baud, the time interval associat- 
ed with each bit of data is 9.09 ms. 

For current loop operation: when 
current is permitted to flow in the cir- 
cuit, you call it the mark condition; 
when current cannot flow, you have 
a space condition. The mark and 
space conditions correspond to a bi- 
nary 1 and 0, respectively. In asyn- 
chronous transmission, the pause or 
gap between characters should be 
mark. 

When an individual character is 
sent, its contents are preceded by a 
start pulse (line 114), which consists 
of 9.09 ms of space. The next eight 
time intervals contain a mixture of 
marks and spaces, in accordance with 



Program listing. Exidy assembly-language program to interface the Teletype Model 33. 


EXIDY Z~ 


80 ASSEMBLER 






A DDR 


OBJECT 


ST 

0001 
0002 










0003 


^^ *^* ^^ ^^ ^^ ^^ ^^ ^w* ^^ ^^ ^^ ^^ ^F* ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^* ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ 






0004 


;* 


* 






0005 


i* SIMPLE 


INTERFACE FOR ASR33 * 






0004 1 


i* by E,E, 


B*rtf*«nn * 






0007 ! 


I * JANUARY 


4, 1981 * 






0008 1 


;* 


* 






0009 


^^ t* ^F^ ^m ^^ *^ ^m ^^ ^^ ^^ ^^ ^F^ ^* ^* ^^ ^F^ ^F^ ^^ ^^ *^ ^F^ ^^ ^F^ ^^ ^F^ ^^ ^^ ^F^ ^^ ^F^ ^^ ^^ ^f^ ^^ ^^ ^F^ ^p ^^ ^^ ^^ 






0010 


PSECT 


ABS 






0011 


1 

1 




>0009 




0012 F 


r FSIZE EQU 


5 


>OOFE 




0013 t 


CEYPRT EQU 


OF EH 


:: 00FF 




0014 F 


•PORT EQU 


OFFH f EXIDY PARALLEL PORT 


>E018 




0015 * 

001 6 1 

0017 i 


CEYBRD EQU 


0E018H 






0018 i 


;*** optional: 


****************** 






0019 i 


!* 


* 






0020 ! 


!* IOINIT 


IS OPTIONAL SINCE* 






0021 i 


>* ONE CAN USE 


THE MONITOR * 






0022 i 


I* COMMAND f "SET I=fO='*ETC * 






0023 i 


!* 


* 






0024 1 


1* IT IS A CONVENIENCE IF ONE * 






0025 J 


* DOES NOT USE 


THE RST AREA * 






0026 J 


* 


* 






0027 J 


************ ******************** 






0028 


ORG 


2AH 






0029 


GLOBAL 


IOINIT 


002A 


D5 


0030 ] 


[OINIT PUSH 


DE 


002B 


E5 


0031 


PUSH 


HL 


002C 


2A00F0 


0032 


LD 


HL»(0F000H) ,, ^ 


002F 


11D1FF 


0033 


LD 


DEfOFF92H + 3FH (More^. 



Microcomputing, December 1981 11 



the bit pattern of the byte that is be- 
ing sent. This software UART sends 
two more intervals of mark (two stop 
pulses); the first stop pulse is the 
ninth and last pass through ULOOP, 
since, originally, the carry flag was 
set (line 116). The second stop pulse 
is created by jumping from ULOOP 
to MARK -»- 2 (line 122). 

The space and mark intervals are 
generated by the routines SPACE and 
MARK. They share a common timing 
loop, DELAY, where the time inter- 
val is controlled by the value of the 
variable PAUSE (introduced in line 
88). 

The CTRLS Routine 

Lastly, I'll describe CTRLS (starting 
at line 170), which looks for and han- 
dles control-S; it is called from the be- 
ginning of CHOUT. 

To find out if a control-S is pressed, 
it is not necessary to scan the whole 
keyboard, such as is performed by 
the monitor routine KEYBRD. A very 
limited scan is done by sending 3 to 
the keyboard port (KEYPRT) and in- 
putting from that same port, testing 
only bit 2 (lines 171-174); if this bit is 
zero, the S key is pressed. The routine 
then looks to see if the CTRL key is 
also pressed (lines 178-181). 

If these keys are not both pressed, 
then CTRLS returns without doing 
anything. However, if the control-S 
combination is pressed, you end up at 
YES (line 185). YES will scan the key- 
board repeatedly until the keys are 
released before we get to K2 (line 
187). K2 waits until another character 
is typed; while it is waiting, the listing 
has stopped and you can examine the 
display at your leisure. The listing re- 
sumes when you type that second 
character that K2 expects. Because 
K2 uses CHIN (line 187), you can turn 
the printer on or off with a control-P. 

Conclusion 

This package has given me great 
pleasure. It is useful even without the 
printer because the listing can be 
stopped or slowed whenever you 
want. With the printer you may ab- 
stract, letting the listing fly by until 
the portion of interest is reached. 
Pressing control-S stops the display; 
pressing control-P readies the print- 
er; and pressing any key restarts/re- 
sumes the listing, this time with the 
printer engaged. When the printout 
becomes uninteresting, use control-S, 
control-P and any key to stop the list- 
ing, disengage the printer and resume 
high-speed CRT display. ■ 

78 Microcomputing, December 1981 



Listing continued. 












0032 


19 


0034 




ADD 


HL 9 DE 




0033 


115B00 


0035 




ID 


DE 9 CHOUT 




0036 


1803 


0036 
0037 
0038 


* 

r 


JR 

ORG 


RST7+3 $ 

38H JRST 7 LOCATION 




0038 


C3A3C0 


0039 
0040 


R8T7 

* 
9 


JP 


0C0A3H FUSED BY DDT 




003B 


73 


0041 




ID 


( HL ) 9 E 




003C 


23 


0042 




INC 


HL 




003D 


72 


0043 




LD 


< HL ) 9 D 




003E 


23 


0044 




INC 


HL 




003F 


115000 


0045 




ID 


DErCHIN 




0042 


73 


0046 




LD 


<HL) >E 




0043 


23 


0047 




INC 


HL 




0044 


72 


0048 




ID 


( HI. ) 9 D 




0045 


El 


0049 




POP 


HI 




0046 


Dl 


0050 




POP 


DE 




0047 


C9 


0051 




RET 










0052 


;*** END OF (OPTIONAL) IOINIT *** 








0053 


* ^/ ^f ^/ *A* «4# \A# - X» ^U ^« -J» J/ ^^ ^^ ^j \t/ ^j ^^ ^^ ^^ -Jj -J.- ■^^ -At ^Lf -^ -^j ^^ J. ^^ ^^ J/ ^^ 
9 ^. ^C ^^ ^^ ^^ ^^ ^^ ^^ T' ^" *■ ^n ^n T^ '* ^^ ** ^^ ^^ ^P » ■ ^" ^" ^' ^^ "'■ *■ '^ ** ^n ^' 'r 








0054 


r 












0055 


* 












0056 


;*** CHARACTER 


input routine: *** 








0057 


* 
9 












0050 




GLOBAL 


CHIN 








0059 


A 

9 








0048 


3A6900 


0060 


YEP 


LD 


A, (STATE) ;FLIP STATE 




004B 


2F 


0061 




CPI. 






004C 


326900 


0062 




LD 


(STATE) 9 A 




004F 


Fl 


0063 




POP 


AF 




0050 


CD18E0 


0064 


CHIN 


CALL 


KEYBRD 




0053 


C8 


0065 




RET 


Z J NO CHAR YET 




0054 


F5 


0066 




PUSH 


AF 




0055 


FE10 


0067 




CP 


10H fCTRL-F"? 




0057 


28EF 


0068 




JR 


ZfYEP-$ 




0059 


Fl 


0069 




POP 


AF 




005A 


C9 


0070 
0071 
0072 


* 
9 

* 

9 


RET 










0073 


?*** CHARACTER 


output routine: ** 








0074 


* 
9 












0075 




GLOBAL 


CHOUT 








0076 


* 
9 








005B 


CDDBOO 


0077 


CHOUT 


CALL 


CTRLS 




005E 


F5 


0078 




PUSH 


AF 




005F 


3A6900 


0079 




LD 


A> (STATE) 




0062 


A 7 


0080 




AND 


A 




0063 


2009 


0081 




JR 


NZ* PRINT-* 




0065 


Fl 


0082 


TOY ID 


POP 


AF J TO video in 




0066 


C31BE0 


0083 
0084 


* 
9 


JP 


0E01BH JMONITOR 








0085 


i*** SY 


stem var: 








0086 


A 

9 








0069 


00 


0087 


STATE 


DEFB 


J0=N0 PRINT 




006A 


B004 


0088 


PAUSE 


DFFW 


04B0H J110 BAUD 




006C 


401F 


0089 
0090 


UAIT 

* 

9 


DEFW 


8000 ICR -LF 




006F. 


Fl 


0091 


PRINT 


POP 


AF 




006F 


F5 


0092 




PUSH 


AF 




0070 


E5 


0093 




PUSH 


HL 




0071 


CD/900 


0094 




CALL 


PTYO 




0074 


El 


0095 




POP 


HL 




0075 


18EE 


0096 
0097 


* 
9 


JR 


TOVID-f 




0077 


3E27 


0098 


APOSTR 


LD 


A»27H ; APOSTROPHE 




007* 


FE7B 


0099 


PTYO 


CP 


'z'+l J REGS DESTROYED 




007B 


DO 


0100 




RET 


NC 




007C 


FE60 


OlOt 




CP 


6 OH 




007E 


28F7 


0102 




JR 


Z » APOSTR * 




0080 


3802 


01^3 




JR 


Cr NOTLC $ 




0082 


D620 


0104 




SUB 


20H ILC -> UC 




0084 


FEOA 


0105 


NOTLC 


CP 


OAH 




0086 


2835 


0106 




JR 


Z»L.F-$ 




0088 


FEOD 


0107 




CP 


ODH 




008A 


283D 


0108 




JR 


Z.CR-* 




008C 


FEOC 


0109 




CP 


OCH J "CLEAR SCREEN" 




008E 


283E 


0110 
0111 


* 

9 


JR 


Z*FF~* 




0090 


F5 


0112 


UART 


PUSH 


AF 




0091 


E5 


0113 




PUSH 


HL 




0092 


CDA400 


0114 




CALL 


SPACE 




0095 


2E09 


0115 




LD 


L»9 




0097 


37 


0116 




SCF 






0098 


IF 


0117 


ULOOP 


RRA 






0099 


DCA900 


0118 




CALL 


CrHARK 




009C 


D4A400 


0119 




CALL 


NCt SPACE 




009F 


2D 


0120 




DEC 


1 S~> 




00A0 


20F6 


0121 




JR 


NZ > ULOOP * (More . 





Listing continued. 








00A2 1807 


0122 
0123 ; 


JR 


MARK+2 $ 


00A4 F5 


0124 SPACt 


PUSH 


AF I'ZERO' 


00A5 AF 


0125 


XOR 


A 


00A6 D3FF 


0126 


OUT 


(PPORT) , A 


00A8 Fl 


0127 


POP 


AF 


00A9 F5 


0128 MARK 


PUSH 


AF » 'ONE' 


OOAA E.5. 


0129 


PUSH 


ML 


OOAB 2A6A00 


0130 


LD 


Ht.9 (PAUSE) 


OOAE 23 


0131 DELAY 


INC 


HI. 


OOAF 24 


0132 


INC 


H 


OOBO 2D 


0133 DLOOP 


DEC 


L 


00B1 20FD 


0134 


JR 


NZ,IU. OOP $ 


00B3 25 


0135 


DEC 


H 


00B4 20FA 


0136 


JR 


NZ,DI ...OOP-* 


00B6 3EFF 


0137 


LD 


A,OFFH 


00B8 D3FF 


0138 


OUT 


(PPORT), A 


OOBA El 


0139 


POP 


HL 


OOBB Fl 


0140 


POP 


AF 


OOBC C9 


0141 
0142 f 


RET 




OOBD F5 


0143 LF 


PUSH 


AF ; LINEFEED 


OOBE 3E0A 


0144 


LD 


ArOAH 


OOCO CD9000 


0145 UARTU 


CALL 


UART J UART f DEL AY 


00C3 E5 


0146 


PUSH 


HL 


00C4 2A6C00 


0147 


LD 


HL, (WAIT) 


00C7 18E5 


0148 


JR 


DELAY-* 


00C9 F5 


0149 CR 


PUSH 


AF * CARRIAGE 


OOCA 3E0D 


0150 


LD 


A/ODH ; RETURN 


OOCC 18F2 


0151 
0152 ; 


JR 


UARTW * 




0153 




f FORMFEED 


OOCE CDC900 


0154 FF 


CALL 


CR JLEAVES FFSIZE OF 


00D1 C5 

^% #% W* f*-^ ^* M *> ■ ■■ , 


0155 


PUSH 


DC ; BLANK LINES ON PRINT 


00D2 0605 


0156 


LD 


B, FFSIZE 


00D4 CDBDOO 


01.57 FFLOOP 


LF 


00D7 10FB 


0158 


EUNZ 


FFLOOP-* 


00D9 Cl 


0159 


POP 


BC 


OODA C9 


0160 
0161 ; 


RET 






0162 ****** CTRLS: ******************* 




0163 ;* 




* 




0164 ;* 


CHECKS 


TO SEE IF CTRL-S * 




0165 J* IS 


PRESSED. 


IF SO, IT WAITS * 




0166 J* UNTIL A SECOND KEY S PRESSED* 




0167 ft 




* 




0168 A > ******************************** 




0169 ? 






OODB F5 


0170 CTRLS 


PUSH 


AF 


OODC 3E03 


0171 


LD 


A, 3 


OODE D3FE 


0172 


OUT 


(KEYPRT), A 


OOEO DBFE 


0173 


IN 


A, (KEYPRT) 


00E2 E604 


0174 


AND 


4 


00E4 2802 


0175 


JR 


Z, CTRLQ * 


00E6 Fl 


0176 


POP 


AF 


00E7 C9 


0177 


RET 




00E8 3E00 


0178 CTRLQ 


LD 


A,0 ICTRL PRESSED? 


OOEA D3FE 


0179 


OUT 


(KEYPRT) ,A 


OOEC DBFE 


0180 


IN 


A, (KEYPRT) 


OOEE E604 


0181 


AND 


4 


OOFO 2802 


0182 


JR 


Z,YES~* 


00F2 Fl 


0183 


POP 


AF 


00F3 C9 


0184 


RET 




00F4 CD18E0 


0185 YES 


CALL 


KEYBRD JBOTH KEYS PRESSED 


00F7 28F.B 


0186 


JR 


Z,YES * 


00F9 CD5000 


0187 K2 


CALL 


CHIN ; ENABLE OPERATOR TO 


OOFC 28FB 


0188 


JR 


Z,K2* 5CHANGE PRINT STATE 


OOFE Fl 


0189 


POP 


AF 


OOFF C9 


0190 
0191 ; 


RET 






0192 f ************************ 




0193 p* END SHOULD NOT * 




0194 ?* 


OVERWRITE 100H * 




0195 f ************************ 




0196 ; 






ERRORS=0000 








APOSTR 0077 


CHIN HINTD 


0050 CHOUT tlNJl 005B 


CR 00C9 


CTRLQ 


00E8 CTRLS OODB 


DELAY OOAE 


DLOOP 


OOBO FF 


OOCF 


FFLOOP 00D4 


FFSIZE 


0005 IOINIT CINT3 002A 


K2 00F9 


KEYBRD 


E018 KEYPRT OOFE 


I-F OOBD 


MARK 


00A9 NOTI. 


C 0084 


PAUSE 006A 


PPORT 


OOFF PRINT 006E 


PTYO 0079 


RST7 


0038 SPACE 00A4 


STATE 0069 


TOVJD 


0065 UART 


0090 


UARTW OOCO 


ULOOP 


0098 WAIT 


006C 


YEP 0048 


YES 


00F4 





Call 

For 



Manuscripts 

Kilobaud Microcomputing is 
looking for business articles! 

Businessmen in all fields are be- 
ginning to take notice of the micro- 
computer. They are eager to know 
which computers, peripheral equip- 
ment and applications software will 
let them take full advantage of this 
new tool. What knowledge do you 
have to share? 

Here are the kinds of articles that 
we want you to write for us: 

• Are you a businessman with a 
system up and running? We want to 
know how it works. What were your 
expectations? Have they been ful- 
filled? Did you find the software that 
you wanted? What problems have 
you had? How did you overcome 
them? What recommendations do 
you have for other businessmen? 

• We want reviews from a busi- 
nessman's perspective of specific 
hardware and software. If you've re- 
cently bought a new product and 
want to tell others how great— or 
poor— it is, Microcomputing wili 
provide you with a forum. 

• What programs have you written 
to meet your specific needs? Per- 
haps another businessman can use 
them, too. Even if he can't, your pro- 
gram may serve as a springboard 
for other ideas. 

• Perhaps you aren't using your mi- 
cro for business, but know a com- 
pany that is. Trot on down with your 
pencil and notebook, and find out 
what they're up to. While they might 
not have the time to write up their 
experiences, they might be more 
than willing to tell somebody else 
about them. And an outside obser- 
ver will often be able to see things 
with a unique and valuable perspec- 
tive. 

Don't worry if you're not a profes- 
sional writer. That's what we editors 
are here for. And we'll be more than 
happy to send you a copy of our 
writer's guidelines. 

Send your manuscripts and cor- 
respondence to: 
Kilobaud Microcomputing 
Pine St. 
Peterborough, NH 03458 



Microcomputing, December 1981 79 



You do, if you use your Apple for telecommunications purposes. 



Data Capture: 

Who Needs It? 



By David Goodfellow 



Data Capture 4.0, by Southeastern 
Software, is advertised as "the 
most advanced and easiest to use tele- 
communications program for use 
with the Micromodem II or the Apple 
Communications card." After using 
the program for several weeks, I have 
no reason to doubt it. 

Of course, it isn't necessary. When 
I want my Apple to talk with another 
computer, I can always access my 
modem directly by typing in the ap- 
propriate commands. I can read fast 
when the other computer is sending, 
or connect directly to my printer. I 
can give the other guy sloppy input 
by typing directly to him. And I can 
let my Source charges pile up while I 
read my mail or try to send some. No, 
Data Capture 4.0 isn't necessary at 
all. 

But boy, does it make things easy. 
Data Capture 4.0 requires a 48K Ap- 
ple II with at least one disk drive us- 
ing 3.2, 3.2.1 or 3.3 DOS. With it you 
can: 

• Prepare messages off-line and 
squirt them through the phone at 
1 10 or 300 baud— a lot faster than I 
can type. 

•Take down all incoming data at 
either baud rate to read later at 
your convenience— no more eye- 
strain as the information scrolls off 
the top of the screen. 

• Save that data to disk for later 
use— either to print or view on the 
monitor, at your own reading 
speed. 

• Upload or download Applesoft or 
Integer programs as text files— 
which are easily converted back to 
their original program state with 
EXEC. 

• Use a number of "special charac- 
ters' ' which are not normally acces- 

80 Microcomputing, December 1981 



sible to the Apple II— underline, 
left square bracket, back slash, ver- 
tical bar, left and right curly 
brackets. 

Data Capture is sold as a single 
disk, with 24 solid 8-1/2 x 11-inch 
pages of documentation. The manual 
(and the program itself) practically 
begs you to make backup copies, and 
gives step-by-step instructions on 
how to do this. It then tells you how 
to configure one of your backups to 
your system, and how to copy your 
configured backup. If you follow all of 
the instructions, you'll wind up with 
four disks— two unconfigured, and 
two configured. Unless you stack 
them all together and drive a stake 
through their hearts, you should nev- 
er be without a usable copy. 

Booting a configured Data Capture 
disk brings up a blank screen with 
four status lines at the top. More 
about these later. Press escape and 
the master menu is displayed, invit- 
ing you to select one of the following 
features: 

List Text— This displays whatever 
you have in the capture buffer— 
whether you typed it yourself, ac- 
cessed it from a text file or received it 
via telecommunications. The buffer 
is line-oriented (up to 500 lines), and 
you can start your list from any line, 
stop the listing to view the screen and 
then continue, or exit the listing 
feature at any time. 

Delete Text— This allows you to de- 
lete any part (or all) of the material in 
the capture buffer. It's used for edit- 
ing, and for clearing the buffer. 

Insert Text— This lets you insert up 
to ten lines of text at a time anywhere 
within the text in the buffer. If ten 
lines isn't enough, you can do it 
again— and again. The program asks 



the line number you wish the insert 
to precede, and displays that line for 
reference while you enter the new 
text. This function, with Delete Text, 
provides sufficient editing capabili- 
ties to massage the text any way you 
wish. It's not as fancy as most word 
processing programs, but it does the 
job. 

Send Text— Send Text is used when 
you're on line with another system. 
Escape to the menu and hit S. The 
program asks you a starting and end- 
ing line number to send; when you 
give it these numbers, the text is on 
its way. Or press A for all, and all the 
text in the buffer goes. 

Print Text— Print Text sends the 
contents of the buffer to the printer, 
with the same choices as mentioned 
in Send Text. 

Write to File— This feature writes 
the entire contents of the buffer to a 
text file on disk, under any name you 
choose. If you choose a name that 
already exists on the disk, it will tell 
you so and ask if you wish to over- 
write it. If not, you can escape and try 
again, using another file name. 

Note that this feature is automatic 
if you have allowed the buffer to fill 
up. In this case, the program writes 
the contents to disk under the name 
"Overflow" "-1," "-2," etc. If you 
already had an " Overflow- 1" on the 
disk from a previous session, you've 
lost it. This would be considered a 
pilot error— not the program's fault. 

Merge from File— This reads the 
contents of any text file you name 
from disk to buffer. 

Catalog Disk— I most often use this 
with Merge from File— mainly be- 



Address correspondence to David C. Goodfellow, 
PO Box 66834, Seattle, WA 98166. 



cause I can never remember the 
name I used to write to file. 

Enter Phone Number— This is used 
with the Micromodem only. The pro- 
gram asks you to type in the phone 
number desired, and after giving you 
a chance to verify it, calls the 
number. If you are using The Source 
and have configured Data Capture 
4.0 to use the function, you may type 
S for the phone number and the pro- 
gram will call in and log on for you. 
Hang Up Phone— Micromodem on- 
ly. Hangs up phone. 

Await Call— Micromodem only. 
This lets you set up the computer for 
remote access. The computer expects 
another computer. "If a man an- 
swers, hang up." 

Quit Program— Soft exit. You can 
quit the program through this selec- 
tion without losing anything in 
memory. This allows you to catalog 
the disk and delete, rename or other- 
wise fiddle with your files. GOTO 
1000, and you're back in business. 
Or, you can quit for good. 

Toggle— This feature presents a 

separate menu of two-state functions 

which can be switched back and 

forth. These functions are: 

•Alternate Drive (1 or 2). With this 

you can write, read or catalog on 

either drive. Default value is 1. I 

like to use drive 2 for text files, so I 

don't fill up the disk the program is 

on. Of course, the whole program 

is in memory, so single-drive users 

can simply replace the program 

disk with an initialized data disk. 

• Baud Rate (110/300). Set as re- 
quired. 

• Capture (on/off). Extremely valu- 
able. With this you can avoid cap- 
turing information you know you 
won't want to keep— such as intro- 
ductory lines of bulletin board sys- 
tems, etc.; then you can turn the 
function on when you're ready to 
receive the information you're 
after. 

•Duplex (full/half). Use half duplex 
when off-line, and full when com- 
municating with those systems that 
need it. 

• Local Carrier (on/off). Micromo- 
dem only. This is useful when two 
Apple owners wish to suspend 
computer communications and 
talk by voice. 

• Special Characters (on/off). This 
function, when on, lets the Apple 
use certain characters which are 
not normally available to it. For in- 
stance, I used the underline a few 
days ago to delete a file in The 



Source that was put in by an ex- 
user of my account. The file was 
sitting in there running up the bill, 
with the underline character part 
of the file name. The Source cus- 
tomer service could have taken it 
out for me, but it's much more 
satisfying (and certain) when you 
do it yourself. 
•Transmit (on/off). You can use this 
function while on-line to type 
something into your buffer without 
sending it to the other station. 
When not in the master menu, the 
screen is clear except for the contents 
of the capture buffer and the status 
lines at the top of the screen. These 
lines show the state of the toggle 
functions, plus one other indicator, 
Lines. This function does not toggle. 
It merely tells you how many lines of 



When the program comes up, you 
press escape for the menu, E for 
enter, and S for Source. The program 
displays your local Telenet or 
Tymnet phone number and asks if 
it's correct (it always is, if you 
entered it right the first time). You 
press Y for yes, and Data Capture 
takes if from there, dialing in and log- 
ging on for you. 

When The Source comes on you go 
directly to MAIL, READ, and sip 
your coffee or something else while 
your mail is being dumped at 110 or 
300 baud. You don't take notes. You 
don't risk eyestrain or mental fatigue 
trying to keep up with your mail 
while it scrolls off the screen. When 
all your mail is in, you type quit, then 
off. The Source logs you off, after 
which you hit escape and select H 



You dump the mail to your printer 

or to disk for later viewing. 

If you don't have a printer, 

you can reread the mail through the display 

as often as you wish. 



text you have in your buffer. When it 
nears 500, you know you had better 
transfer it to disk— or the program 
will do it for you. This is useful when 
you wish to download a program 
which you know will take most of the 
buffer. It helps you make the judg- 
ment. 

Note that every function on the 
menu is available to you even while 
you are on line. When you press 
escape to go to the menu, Data Cap- 
ture sends a stop code (CTRL-S) 
recognized by most remote services, 
so that incoming data is not lost while 
you choose a function. Resume oper- 
ation with whatever code the other 
system recognizes— usually any key, 
return or CTRL-Q. 

Let's say you're carrying on a cor- 
respondence with Source (or other 
timeshare system) users. Your last 
bill almost did in the family Lord Ex- 
chequer and you have to cut the costs 
or sell Aunt Minnie's diamonds to 
stay solvent. Since Aunt Minnie's big- 
ger than you are, the latter solution is 
dangerous. 

Enter Data Capture 4.0. 

You place into your disk drive a 
disk which you have configured ac- 
cording to explicit instructions in the 
documentation, and "PR#6" it. 



(hang up) from the menu. 

Then, on your own time (the 
meter's not running anymore), you 
dump the mail to your printer or to 
disk for later viewing. If you don't 
have a printer, you can reread the 
mail through the display as often as 
you wish. 

Still off-line, you answer each piece 
of mail by typing it into Data Capture, 
using the program's delete and insert 
features to edit what you've done. 
When all your mail is answered, you 
jump back into The Source and send 
it— faster and more accurately than 
you could have typed it on-line. 

The two Source sessions together 
cost a lot less than if you had done it 
manually in one session. Aunt Min- 
nie's diamonds are safe! 

Just for fun the other night I took 
(downloaded) an Apple program 
from a public access file belonging to 
another user of The Source. The oth- 
er user had left it as a text file for that 
purpose. Data Capture took it easily, 
and on command dumped it to disk. I 
then exited Data Capture and went to 
Integer— still in DOS. 

With the command EXEC RAN- 
DOM SENTENCES, I brought it into 
memory as the Integer program it 
was, then rewrote it to disk with 



Microcomputing, December 1981 81 



SAVE RNDM SENTENCES. Not 
needing the text file any more, I 
typed DELETE RANDOM SEN- 
TENCES. That's all there was to it! 
RNDM SENTENCES is available to 
me whenever I want it, and it runs 
beautifully. 

You can send Applesoft or Integer 
programs just as easily, by converting 
them to text files with the program 
called (appropriately) CREATE.TXT, 
and included on the disk. The only 
requirement for any data to be up- 
loaded or downloaded is that it be 
formatted as a text file. 

Occasionally, I like to advertise a 
certain product or service in bulletin 
board systems across the country. I 
look forward to trying it with this 
program, because last time I did it 
(manually) the long distance charges 
just about cancelled the profits— and 
my ads didn't look that great because 
it's hard for me to type and proof 
copy with the knowledge that Ma 
Bell's meter is ticking. 

With Data Capture 4.0, I'll prepare 
the ad off-line, and when it's done to 
my satisfaction, I'll go down the list 
of bulletin boards, call each in turn, 
squirt my message at it, and hang 



up— hit and run. Each call will be 
under three minutes, and I'm betting 
that my phone bill will be con- 
siderably less than when I did it 
manually. 

No, Data Capture 4.0 isn't neces- 
sary. But if you're into telecom- 
munications, it takes away most of 
the drudgery and shuts off the meter 
a lot quicker. Isn't that what com- 
puters are all about— automating the 
drudgery jobs and cutting costs? 

There are some things I'd like 
changed. For instance, timeshare sys- 
tems like The Source operate full- 
duplex. This means that the system 
echoes back to your Apple every- 
thing you send, character-by-charac- 
ter (invisibly, of course). The pro- 
gram handles this all right, except for 
line feeds. Every time you press re- 
turn you get two— one from your key- 
board and one from the echo. This 
can fill the buffer pretty fast. 

I'd like to see the program made 
compatible with some of the other 
modems hitting the market. Many 
bulletin boards support 600 baud and 
faster. When you're operating long 
distance, faster is cheaper. 

I suppose that the send routine 



could be speeded up a little if it didn't 
have to wait for the echo of each 
character sent. But speeding it up in 
this way may not be a good idea. I 
think I prefer the confirming echo. 

Every day it becomes harder to find 
major faults with Apple software that 
is being sold successfully. A couple of 
years ago users were happy with a 
program which could play a reason- 
able game of tic-tac-toe without 
crashing every third game. Now, pro- 
grams are more sophisticated and 
distributors more critical. The result 
is software that is user-oriented, 
relatively crash-proof, and very, very 
useful or entertaining. Programs that 
aren't just don't make it. This one 

made it. 

Data Capture 4.0 is probably avail- 
able at your local computer store, 
listing for $65. If you can't find it 
there, try Southeastern Software, 
6414 Derbyshire Drive, New Or- 
leans, LA 70126. Owners of the pre- 
vious version, Data Capture 3.0, can 
upgrade by sending in their old disk 
and documentation, plus $37.50. The 
program is written in Applesoft and 
machine language, and supports the 
Paymar lowercase adapter. ■ 



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Are you looking for. 



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When you subscribe to a magazine, you want to get REAL 
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When you subscribe to a magazine, you want to pay for 
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Microcomputing has been running around 40% advertising 
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Microcomputing, December 1981 83 




Business Is 



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Gene Cayot, Sales Manager, MSI. . • 

We have been building commercial quality computer systems for 1 1 years 
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countries where MSI Business Systems are sold. 



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Expandability 

Our systems do not have built-in obsolescence. Any MSI computer 
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IBM's entry into the microcomputing fray with its 16-bit Personal Computer 

will give the industry a big boost. 



IBM Thinks Small 



By G. Michael Vose 



Hundreds of thousands of Amer- 
icans have seen an IBM comput- 
er in their local bank or at the office 
where they work. IBM means com- 
puters to many people. Therefore, a 
Personal Computer with the name 
IBM on it will sell a million, right? 

Perhaps not. The new IBM Person- 
al Computer will be a solid invest- 
ment for anyone who needs a com- 
puter, but it is, above all, a computer. 
Not everyone needs or wants a com- 
puter—some people are even anti- 
computer. But it would seem, based 
upon a look at the Personal Comput- 
er, that IBM has, at least, done every- 
thing right while making its first truly 
personal computer. 

The Right Combination 

The executives at IBM apparently 
used this formula in developing the 
Personal Computer: Make it expand- 
able for the future. Make it compati- 
ble with existing software. Make it at- 
tractive. And make it easy to use. 

It is hard to imagine how you could 
go wrong with this formula, and it 
would be a safe bet that IBM will suc- 
ceed in selling many Personal Com- 
puters in the years ahead: not simply 
because of the name IBM, but be- 
cause the company has obviously 
learned a great deal from other man- 
ufacturers' mistakes. 

The instruction manuals are the 
first clue. IBM has used its vast cor- 
porate resources and a well-trained 
staff of technical writers to prepare 

86 Microcomputing, December 1981 




The IBM Personal Computer with video display, two disk drives and 80-column printer. 



the most thorough, easy-to-under- 
stand instruction manuals I've ever 
seen. I would even hesitate to call 
these manuals documentation, be- 
cause they are so well written they 
don't seem to fit into that category; 
typically, documentation is stilted 
in style and full of awkward con- 
ventions. 

The Personal Computer comes 
with four manuals (if configured for 
disk operation), a BASIC language 
manual, a disk-operating system 
manual, a manual on setting up the 
computer, and a separate manual de- 
scribing all the additional peripherals 
and the software you can buy. A fifth 



manual will become available soon, 
for an extra $150, containing the 
technical and repair information for 
the system. 

These manuals are remarkably free 
of jargon, at least until you are ready 
for some, and are bound in hardcover 
6 by 9 inch three-ring binders. 

The Personal Computer looks 
good. The keyboard, system unit and 
video display are housed in separate 
boxes attached to one another by 
cables. This modular design gives the 

G. Michael Vose is a technical editor for 
Microcomputing magazine. 

Reader Service for facing page ^42 







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computer flexibility. The keyboard, 
for example, can be moved up to six 
feet away from the rest of the system. 
It can be held in your lap for comfort 
and ease of use. The components 
have a modern look but avoid the 
NASA laboratory look of some new 
computers. Like a stereo system, the 
Personal Computer would not be out 
of place in your living room. 

The Soul of the 
Personal Computer 

Technically, the IBM Personal 
Computer is a second-generation mi- 
crocomputer. It uses the Intel 8088 
16-bit microprocessor, which can ad- 
dress up to 256K bytes of user memo- 
ry. The processor is driven by a 4.77 
MHz clock and has a 410 nanosecond 
cycle time. 

Because IBM elected to upgrade to 
a 16-bit processor for its new ma- 
chine, the Personal Computer can 
open up new possibilities to the small 
computer user. 256K bytes of memo- 
ry will allow four times as much data 
handling as the eight-bit machines 
that have been the microcomputer 
standard up to now. 

It can, however, be configured 
with as little as 16K bytes of user 
memory. In this configuration it car- 
ries a modest $1595 price tag, bring- 
ing it well within reach of most 
homeowners and neophyte comput- 
erists. Since the system can be up- 
graded at any time, the minimum 
system will suffice to introduce many 
people to computers while allowing 
others to build a more powerful sys- 
tem for a specific application. Memo- 




TV IBM's graphics demos are very impressive. (The overlapping at the left side of the photo resulted from 
a camera not a computer problem.) 



ry boards in 16K, 32K and 64K config- 
urations are available to add to the 
system's power. These boards can be 
added by the owner. Simply plug 
them into slots inside the system unit. 
It is not necessary to have this up- 
grade performed by a dealer at addi- 
tional cost. 

The expansion slots in the system 
unit accept a variety of peripheral in- 
terfaces as well as additional mem- 
ory. These include video-display 
adapters, allowing the use of an IBM 
monitor or a regular television set as 
a monitor; a printer adapter; commu- 
nications adapter; and game adapter, 




One of the Personal Computer's diagnostics tests the keyboard. As each key is pressed, its 
character appears on the screen if it is working properly. 

88 Microcomputing, December 1981 



the latter allowing the use of game 
paddles or joysticks. All these adapt- 
ers add to the cost of the computer. 

The Personal Computer has a built- 
in speaker for music programming or 
prompting. When the system is 
turned on, a diagnostics program in 
the computer's pre-programmed 
memory checks the components of 
the system to ensure that all the parts 
are functioning. The cassette tape 
player jack accepts all standard mod- 
el cassette tape recorders. The 83-key 
keyboard contains ten special func- 
tion keys and ten keys for numeric 
entry and cursor control— this nu- 
meric keypad must be activated be- 
fore use. The enter or return key on 
the Personal Computer is marked on- 
ly by a stylistic arrow that curves 
from the vertical to the left, a rather 
strange departure from traditional 
return key marking. 

The data storage options include 
cassette tape and 5V4-inch floppy 
disks. The disk drive systems may be 
configured with one, two or four sep- 
arate drives. The drives are double- 
density controlled, allowing 160K 
bytes of data per disk. The disk 
drives, like the expansion memory 
boards, can be installed by the user. 
The disks are formatted with 40 
tracks, eight sectors per track and 512 
bytes per sector. The disk drives, re- 
portedly built by Tandon, have a 
power delay circuit built in that al- 
lows the system to be turned on and 
off with a disk in the drive. No dam- 
age can result to the disk because the 



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50/3.30 
50/4.10 



Diskette Storage Pages 10/6.95 



3M HEAD CLEANING KIT 



5"SS,SD 10/2.80 50/2.70 

8"SS,SD 10/2.90 50/2.80 

8"SS,DD 10/3.50 50/3.40 

8" DS, SD 10/4.50 50/4.40 

8" DS, DD 10/4.50 50/4.40 

Disk Flip 'N File Case 5" 22.95, 8" 27.95 

Disk Library Case 5" 2.05, 8" 2.80 

PAPER & LABELS 



• Eliminate downtime 

• Eliminate service calls 

• Increase life of read- 
write heads 

• Cleans in 30 seconds 

• Removes dust. dirt, 
magnetic oxides 

5 1 /4"or8" 



$ 19.50 

PRINT WHEELS 



Greenbar 14 «x 1 1 
one part 3000 sheets 

two part 1300 sheets 

White 9' x11 

one part 3500 sheets 

two part 1400 sheets 

Labels 3 x 

one across box of 5000 

two across box of 10.000 



39.95 
45.95 

29.95 
33.95 

17.30 
34.60 



RIBBONS 



Mfr. 

Diablo 
Qume 
NEC 



^63 



Mfr. 

Diablo 
Qume 
NEC 



Doz. 

7200 
4350 
71.50 



Call for quantity prices — Minimum $1. 75 shipping and handling. ^ 63 



— DSI — 



DAVIS SYSTEMS INC. 

2184 Meadowcliff Drive NE„ Atlanta, GA 30345 

(404) 634-2300 




Unheard of Discounts 

on all Micro-Computer 

Equipment and Software 



Including: 

• Apple 

• TRS-80 

• Commodore/Pet 

• Atari 

• Zenith 



Corvus 

Cameo 

Anadex 

C-Itoh 

Epson 



All equipment includes 
full factory warranties . 



DISK DRIVE WOES? 

PRINTER INTERACTION? 

MEMORY LOSS? 

ERRATIC OPERATION? ^W ^^^^ ' 

Don't wtv — 

Blame The ^^ 
Software! V^ 

Power Line Spikes. Surges & #4 .259.705 ^ ,Sa2 

Hash could be the culprit! ^^ 

Floppies, printers, memory & processor often interact! Our 
patented ISOLATORS eliminate equipment interaction AND curb 
damaging Power Line Spikes, Surges and Hash. 

• ISOLATOR (ISO-1) 3 filter isolated 3 prong sockets; integral 
Surge/Spike Suppression; 1875 W Maximum load, 1 KW load any 
socket $62.95 

• ISOLATOR (ISO-2) 2 filter isolated 3 prong socket banks; (6 
sockets total); integral Spike/Surge Suppression; 1875 W Max 
load, 1 KW either bank $62.95 

• SUPER ISOLATOR (ISO-3). similar to ISO-1 except double 
filtering & Suppression $94.95 

• ISOLATOR (ISO-4), similar to ISO 1 except unit has 6 
individually filtered sockets $106.95 

• SUPER ISOLATOR (ISO-1 1) similar to ISO-2 except double 
filtering & Suppression $94.95 

• CIRCUIT BREAKER, any model (add-CB) Add $ 8.00 

• CKT BRKR/SWITCH/PILOT (CBS) Add $16.00 

AT YOUR Master-Card, Visa, American Express 

DEALERS Order Toll Free 1-800-225-4876 

(except AK, HI, PR & Canada) 



/SJ Electronic Specialists, Inc. ^93 

171 South Main Street Natick. Mass. 01760 

Technical & Non-800: 1-617-655-1532 



Try these Hard Shelled prices on for 

size: 

Apple II + 48k 

Atari 800 1 6k 

Commodore Vic 20 

TRS-80 III 48k 2 Dr. 

Anadex 9501 

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1 190.00 

775.00 

259.00 

2195.00 

1325.00 

425.00 



ARMADILLO 

COMPUTER 
COMMUTER 



^319 




P.O. Box 61486 N - I v 

DFW Airport, TX 75261 

Ordering Line 

Call 214-254-5511— Dept. Alice 



See List of Advertisers on page 210 



Microcomputing, December 1981 89 



Big sale 
onK'si 

16K... $149.95 
32K...S 199.95 
48K... $249.95 
64K . . . $299.95 




New JAWS-IB 

The Ultrabyte Memory Board 

Due to the tremendous success of our JAWS I, we 
were able to make a special purchase of first-quality 
components at below-cost prices for JAWS-IB. And 
we are sharing our cost saving with you. But don't be 
surprised if the next time you see this ad the prices 
have gone up substantially. Better yet, order now, 
and get the best memory on the market at the best 
price on the market. 

ONE CHIP DOES IT ALL 

laws-IB is the Rolls-Royce of all the S100 dynamic 
boards. Its heart is Intel's single chip 64K dynamic 
RAM controller. Eliminates high-current logic parts 
. . delay lines . . . massive heat sinks . . . unreliable 
trick circuits. JAWS-IB solves all these problems. 

LOOK WHAT JAWS-IB OFFERS YOU 
Hidden refresh . . . fast performance . . . low power 
consumption . . . latched data outputs . . . 200 NS 
4116 RAM's . . . on-board crystal . . . RAM Jumper 
selectable on 8K boundaries . . . fully socketed . . . 
solder mask on both sides of board . . . phantom line 
. . . designed for 8080, 8085, and Z80 bus signals . . . 
works in Explorer, Sol, Horizon, as well as all other 
well-designed S100 computers. 



► 



10-IMY MONKY HM k TRIAL: Try a fully wired 
and tested board lor 1 days — then Hi her keep 
ii. return it for kit . or simply relurn II In working 
condition. 



<r 



KB8 



Continental U.S.A. Credit Card Buyers Outside Connecticut: 

TO ORDER CALL TOLL FREE 800-243-7428 

From Connecticut Or For Assistance: 
(203) 354-9375 

Please send the items chocked below 

JAWS-IB kit: 

□ 16K $149.95* 

D 32K $199.95* 

□ 48K $249.95* 

D 64K $299.95* 

JAWS-IB Fully Assembled, Wired & Tested: 

□ 16K $179.95* 

□ 32K $239.95* 

D 48K $299.95* 

□ 64K $359.95* 

D EXPANSION KIT, 16K RAM Module, to expand 

JAWS-IB in 16K blocks up to 64K. $59.95 

*A\\ price's phis $2 postoee and insurance ($4.00 Canada). 
Conneclicul residents add sofas' tax. 



Total enclosed: $ 

D Personal Check □ Money Order or Cashier's Check 

D VISA G Master Card (Bank No. ) 



Acct. No. 

Signature 
Print 
Name 



Exp. Date 



Address 



City 
State 



Zip 



IS, 



NETRONICS R&D Lid. 

333 Litchfield Road, New Milford, CT 06776 



motors and read/write heads are not 
activated. (A problem might develop, 
however, if power fails in the middle 
of a read/write operation.) 

The monitor made by IBM for use 
with the Personal Computer is a 
monochrome display that provides 
25 lines of 80 characters on an IIV2 
inch green phosphor screen. The 
computer offers upper- and lower- 
case letter display and the monitor 
supports underlining, blinking char- 
acters and inverse video. Brightness 
and contrast controls allow adjusting 
the display for reading comfort. For 
color display, IBM offers a graphics/ 
color monitor adapter that interfaces 
the computer to a color monitor, or 
an rf modulator that will permit the 
use of a standard color television set. 

Many independent computer deal- 
ers were chagrined to discover three 
months ago that the new Epson 
MX-80 printers out of Japan had be- 
come hard to obtain. Now the reason 
for that scarcity has become evident. 
The dot matrix printer being sold by 
IBM with the Personal Computer is 
an Epson MX-80 with the IBM name 
on it. The fact that IBM chose this 
high-quality, low-cost printer to ac- 
company its system is high praise for 
Epson, Ltd. The printer is bidirec- 
tional and prints 80 characters per 
second while offering expanded or 
compressed print. The printer also 
has overstrike capability to produce 
near letter-quality print. 

Software from Everywhere 

The IBM Personal Computer uses 
BASIC as its primary language. The 



BASIC interpreter, contained in a 
40K preprogrammed memory, was 
written by Microsoft, Inc., of 
Bellevue, WA. Called BASIC80, Ver- 
sion 5.0, this BASIC, when combined 
with the disk BASIC enhancements 
known as advanced BASIC, is the 
most complete ever produced for mi- 
crocomputers. The language includes 
a Graphics Macro Language and a 
Music Macro Language for the crea- 
tion of sophisticated graphics and 
music routines. BASIC80 also sup- 
ports the use of two printers simulta- 
neously. Up to 16 foreground and 
eight background colors are sup- 
ported by BASIC80. Significantly, the 
interpreter also allows the simultane- 
ous display of color, graphics and 
character information. 

If the BASIC interpreter used in the 
IBM Personal Computer has a fault, it 
is the syntactical requirement that 
spaces be placed between commands 
and numbers. It is required, for ex- 
ample, to have a space between GO- 
SUB and 5000 or between the 1 and 
TO and TO and 1000 in the state- 
ment, FOR X = 1 TO 1000. This is a 
mainframe BASIC holdover that IBM 
probably incorporated to appease its 
long-standing mainframe users, who 
the company hopes will become Per- 
sonal Computer owners. Unfortu- 
nately, the spaces use memory and 
the syntax modification will take 
some adjustment on the part of peo- 
ple used to standard microcomputer 
BASICs that do not require the 
spaces. This will make life slightly 
more difficult for people who plan to 
adapt existing BASIC programs for 



Prnfrnuituil 



REAL ESTATE SOFTWARE 



for APPI K. TRS-80 ♦ PKT 



• PROPERTY MANAGEMENT SYSTEM: 



il 



9 TRACK TAPE DRIVES 



Tenant History 
Late Rent Report 
Vacancy Report 
Income Report 
Auto Late Charge 
Returned Checks 



Ownership Files 
Building Reports 
Utilities Report 
Tax Expense Report 
Prints Checks 
Prints Receipts 



PROPERTY LISTINGS COMPARABI IS: $325 



— SCREEN BY — m 

22 Items/Listing 
1000 Listing/Disk 
Listing Memo Field 



Max/Mm Price 
Units/Zone/City 
Max Price/Income 
Max Price/Sq Foot 
Mm Cashflow 



• REAI ESTATE ANALYSIS MODULES: $40 Module 

Home Purchase • Tax Deterred Exchange 

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• WORD PROCESSOR MAGIC WAND $2s:> 



oftware 



ompany 



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Suite F, Dept K 1116-8th St.. Manhattan Beach, CA 90266 



800 BPI 

45 IPS 

FULL MANUAL 

$4850 VALUE 




$2400 

NEW IN 

ORIGINAL 

BOXES 



PERTEC Model 8840A-9-45 

INDUSTRY STANDARD INTERFACE 

CAPABLE OF IND. STD. ANSI-IBM DATA FORMAT 

• READ/WRITE DATA IN STANDARD ANSI-IBM COMPATIBLE 
FORMAT 

• DUMP WINCHESTERS AND HARD DISKS; 10 inch reels hold up to 
3600 of tap* 34 56 Megabyte* unblocked. 

• EXCHANGE DATA A PROGRAMS WITH LARGE MAIN FRAMES 
AT SCHOOL. WORK. SERVICE BUREAUS ETC. 

• BARGAIN PRICED MINI-COMPUTER UPGRADE OEM List S48S0 

A large OEM overstock makes these industry standard drives available at 
a fraction of their current list price Full size drives handle up to 10 5 inch 
reels of standard inexpensive 1/2 inch mag tape 19 inch rack mount or 
use right out of the box on steel shipping frame 

SPECIFICATION SUMMARY: 9-track. 800 BPI. dual head (read after 
write). 45 IPS read/write. 200 IPS rewind. BOT/EOT sensing. 110 
VAC 60-Hz solid state, recent manufacture, all I/O signals TTL/DTL 
compatible, tension arm tape buffering, full control panel Call or write for 
full set of technical specifications 

INTERFACES: Electrovalue encourages the development of interfaces to 
popular systems Interfaces exist for popular minis and are being 
developed for several hobby computers If you'd like to develop and 
document ar, interface to a popular small system call to discuss 
discounts 



ELECTROVALUE INDUSTRIAL INC. 

P.O. BOX 157-K f 

MORRIS PLAINS. NJ 07950 Ofl 

Formerly Eiaciravaiua industrial [y- \ 




Phone reservation*, and 
questions ere welcome 

201/267-1117 



90 Microcomputing, December 1981 



the Personal Computer. 

The BASIC interpreter is about as 
fast as similar interpreters in the Ap- 
ple and Radio Shack computers, 
printing the numbers 1 to 1500 in 
roughly 49 seconds. The system reset 
for the Personal Computer is a com- 
bination of the CTRL, ALT and DEL 
keys, pressed simultaneously— there 
is no simple reset switch like on 
many other computers. 

To break the execution of a BASIC 
program, you must press the CTRL 
and break keys simultaneously. This 
extra keystroke should have been 
eliminated. The machine does have a 
PRT SC key which allows a dump of 
the screen buffer contents to the 
printer with a simple keystroke oper- 
ation, an attractive feature that most 
computers lack. 

Applications 

In addition to BASIC in the prepro- 
grammed memory, the IBM Personal 
Computer can run a variety of soft- 
ware packages under its CP/M-like 
operating system. IBM has a licens- 
ing arrangement with Digital Re- 
search, the originators of CP/M, to 
use a slightly modified version of the 
operating system under the name, 
IBM DOS. With this operating sys- 
tem, the company has also arranged 
licensing agreements with Personal 
Software, Peachtree Software, Micro- 
soft, Inc., and Information Software 
Unlimited to sell VisiCalc, Account- 
ing and General Ledger, Adventure 
game and the EasyWriter word pro- 
cessing software packages. Commu- 
nication software is also available so 



that the computer can be used with a 
modem to communicate other com- 
puters and information services. 

This software availability will cer- 
tainly make the machine an attrac- 
tive buy. But prospective buyers 
should be aware that none of these 
packages can run on a system with 
only 16K of user memory— Adven- 
ture needs 32K and the rest require 
64K bytes of memory. 

Price and Availability 

The Personal Computer will not be 
inexpensive but, as a second-genera- 
tion machine, it probably shouldn't 
be. With an IBM monochrome dis- 
play, 64K of memory, printer and 
two disk drives, a system will cost 
about $4500. A 48K system with one 
disk drive and no printer will run 
$2295. Additional memory will cost 
$95 to $593. Software packages will 
run from $270 for VisiCalc to $995 
for the Peachtree Accounting pack- 
ages (all prices quoted are from Com- 
puterland). 

IBM has promised that the ma- 
chines will be available after Oct. 
15. The Personal Computer will be 
sold through IBM Business Centers, 
Computerland stores and the new 
Sears Business Systems Centers. 
Speculation is that the com- 
pany may announce eight-inch disk 
drives for the Personal Computer as 
early as February and eventually 
hard-disk drives. 

Whatever happens, this new ma- 
chine from an old company will have 
a substantial, but unpredictable, ef- 
fect on an already volatile industry. ■ 




NEW! for 
the '89 from 



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MICROSYSTEMS 

^234 

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DISK CONTROLLER 

for both 5V4" & 8" drives 




only CpU^JU complete 
including CP/M™2.2 

MAGNOLIA MICROSYSTEMS, INC. 

2812 Thorndyke W.. Seattle 98199 

t206) 285-7266 (800) 426-2841 

CP/M is a trademark of Digital Research. 



_J 



IS YOUR 

°North Star 

OUT OF SORTS? 



INCREASE YOUR BASICS 
SORTING POWER OVER 1800%! 

N*S0RT is easy to use and will perform 
sorts on one and two dimensional or 
string arrays using optional sort keys. 
For example, to alphabetize A$: 

10 A$ - ' ZYXWVUTS'X REM Define String 
20 SRT A$.LEN(A$).1\ REM Sort A$ 

N*S0RT interfaces to any release 4 or 
later North Star Basic and can be yourr 

for ONLY (fcQQ 

<4>OC7 plus $1 .50 shipping 

Cahf. Res add 6% tax 
Send check VISA or M/C 
Complete Brochure Available 

Software Systems 

1269 Rubio Vista Road, Altadena, Calif. 91001 
^__ (213) 791-3202 jf 



^111 




°ComP-*«' s 



Asoo 



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mmm 



$749 

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■■! 



List $ 1080 





ATARI" 400.$. 




Atari 830 Acoustic Modern $159 

Atari 825 80 Col. Impt. Ptr $569 

Atari 16KRam Mem. Mod $79 

Atari 410 Prog. Recorder $69 

Atari 810 Disk Drive $439 



Whp% HEWLETT 
mLUM PACKARD 

HP-85 r ~ 
$2495 



tf^ 




HP-125 I HP-83 
$3089 | $1600 

HP-85 Accessories 

5V4 Dual Master Disk Drive List $2500 . . . $2025 
5V4 Single Master Disk Drive List $1500 . . .$1275 
HP-85 Application pacs standard List $95 . . . $85 
Serial (RS232C) Interface Mod. List $395 . . . $355 
GPIO Interface Module List $495 .$389 

HP-41CVwith five times 
more memory 

built in. 

List $325 

$249 

HP-41C 

List $250 

$189 

HP-41CV Printer List $385 $289 .OO 

HP-41CV Quad Mem $83 95 

HP-41CV CardReader $167 95 

HP-12C $127.00 

HP-HC $115.00 

HP-33C $74.95 

HP-34C $117.95 



ersonal 





ompatQr 
ystems 



^303 




1 



"«sl*< larg* 



609 Butternut Street 
Syracuse, N.Y. 13208 

(800) 448-5259 

In N.Y. coll: (315) 475-6800 

Prices do not include shipping by UPS. 
A II prices and offers 
^suhjecUMhang^witho^ 



See List of Advertisers on page 210 



Microcomputing, December 1981 91 




Introducing 
the Sinclair ZX81 

If you're ever going to buy 
a personal computer, now is the 
time to do it. 

The new Sinclair ZX81 is the 
most powerful, yet easy-to-use 
computer ever offered for anywhere 
near the price: only $149.95* completely 
assembled. 

Don't let the price fool you. The 
ZX81 has just about everything you 
could ask for in a personal computer. 

A breakthrough 
in personal computers 

The ZX81 is a major advance over 
the original Sinclair ZX80-the world's 
largest selling personal computer and 
the first for under $200. 

In fact, the ZX81's new 8K Extended 
BASIC offers features found only on com- 
puters costing two or three times as much. 

Just look at what you get: 

■ Continuous display, including moving 
graphics 

■ Multi-dimensional string and numerical 
arrays 

*Plus shipping and handling Price includes connectors 
for TV and cassette. AC adaptor, and FREE manual. 



■ Mathematical and scientific functions 
accurate to 8 decimal places 

■ Unique one-touch entry of key words 
like PRINT, RUN and LIST 

■ Automatic syntax error detection and 
easy editing 

■ Randomize function useful for both 
games and serious applications 

■ Built-in interface for ZX Printer 

■ 1K of memory expandable to 16K 

The ZX81 is also very convenient 
to use. It hooks up to any television set 
to produce a clear 32-column by 24-line 
display. And you can use a regular 
cassette recorder to store and recall 
programs by name. 



If you already own a ZX80 

The 8K Extended BASIC 
chip used in the ZX81 is available 
as a plug-in replacement for your 
ZX80 for only $39.95, plus shipping 
and handling— complete with new key- 
board overlay and the ZX81 manual. 
So in just a few minutes, with no 
special skills or tools required, you can 
upgrade your ZX80 to have all the 
powerful features of the ZX81. (You'll 
have everything except continuous dis- 
play, but you can still use the PAUSE 
and SCROLL commands to get moving 
graphics.) 

With the 8K BASIC chip, your 
ZX80 will also be equipped to use the 
ZX Printer and Sinclair software. 

Warranty and Service Program** 
The Sinclair ZX81 is covered by a 
10-day money-back guarantee and a 
limited 90-day warranty that includes free 
parts and labor through our national 
service-by-mail facilities. 

"Does not apply to ZX81 kits 







NEW SOFTWARE-.Sinclair has 

published pre-recorded pro- 
grams on cassettes for your 
ZX81, or ZX80 with 8K BASIC. 
We're constantly coming out 
with new programs, so we'll 
send you our latest software 
catalog with your computer. 



ZX PRINTER: The Sinclair ZX 16K MEMORY MODULE: 

Printer will work with your ZX81, Like any powerful, full fledged 



or ZX80 with 8K BASIC. It will 
be available in the near future 
and will cost less than $100. 



computer, the ZX81 is expand 
able. Sinclair's 16K memory 
module plugs right onto the 
back of your ZX81 (or ZX80, 
with or without 8K BASIC). 
Cost is $99.95, plus shipping 
and handling. 



ZX81 MANUAL: The ZX81 
comes with a comprehensive 
164-page programming guide 
and operating manual de- 
signed for both beginners and 
experienced computer users. 
A $10.95 value, it's yours free 
with the ZX81. 




Introducing 
the ZX81 kit 

If you really want to 
save money, and you enjoy 
building electronic kits, you 
can order the ZX81 in kit form 
for the incredible price of just 
$99.95* It's the same, full-featured 
computer, only you put it together 
yourself. We'll send complete, easy- 
to-follow instructions on how you can 
assemble your ZX81 in just a few hours. 
All you have to supply is the soldering iron 

How to order 

Sinclair Research is the world's larg 
est manufacturer of personal computers. 

The ZX81 represents the latest 
technology in microelectronics, and it 
picks up right where the ZX80 left off. 
Thousands are selling every week. 

We urge you to place your order 
for the new ZX81 today. The sooner you 
order, the sooner you can start enjoying 
your own computer. 

To order, simply call our toll free 
number, and use your MasterCard or VISA 

To order by mail, please use the 
coupon And send your check or money 
order. We regret that we cannot accept 
purchase orders or C.O.Dls. 

CALL 800-543-3000. Ask for op- 
erator #509. In Ohio call 800-582-1364. 
In Canada call 513-729-4300. Ask for 
operator #509. Phones open 24 hours 
a day, 7 days a week. Have your Master- 
Card or VISA ready. 

These numbers are for orders 
only. For information, you must write to 
Sinclair Research Ltd., One Sinclair Plaza, 
Nashua, NH 03061. 



PRICEt QTY. AMOUNT 



ZX81 Kit 



8K BASIC chip (for ZX80) 



Memory Module (for ZX81 or ZX80) 



Shipping and Handling 



To ship outside USA add $10.00 



$149.95 



99.95 



39.95 



99.95 



TOTAL 



MAIL TO: Sinclair Research Ltd., One Sinclair Plaza, Nashua, NH 03061 




inczl 




CITY/STATE/ZIP. 

t U.S. Dollars 



With stellar word processing features, Xerox's first microcomputer is destined to 

find a secure place in the business environment. 



Another Industry Giant 
Takes a Micro Step 



By Harold Nelson 
Microcomputing Technical Editor 



Last June Xerox released the Xerox 
820 Information Processor, which 
is described as "a low-cost desktop 
work station that can be used as a 
word processing station, a business 
computer, or both.' Sine its release 
the WORM (wonderful office revolu- 
tionary machine, Xerox's in- house 
code name for the 820) has under- 
gone a name change to SAM (simply 
amazing machine). 

Regardless of what it is called, the 
820 deserves a serious look, if for no 
other reason (and there are other rea- 
sons) than the Xerox name it bears. 

First Impressions 

The first pleasant surprise is how 
easy the 820 is to set up and run. Con- 
necting the components' cables to the 
ports on the display console is sim- 
pler than opening and unpacking the 
individual components. The instruc- 
tions on setup are clear and almost 
unnecessary. 

If the optional printer is to be a part 
of the system, its setup (removing 
protective shipping restraints and in- 
stalling the printwheel) is only slight- 
ly more complicated. Again the in- 
structions are clear and easy to 

follow. 

Booting the system is a matter of 
turning on the console, inserting an 
operating system disk in drive A, typ- 
ing the letter A and pressing return. 

(If you want to use the 820 with a 
printer as an automatic typewriter, 
just type T. What you type is printed 
immediately. Unfortunately, it's not 
displayed on the console screen, 

94 Microcomputing, December 1981 



which makes it nearly impossible to 
visually check what you have typed.) 

Word Processing 

The software package you've 
bought determines what will happen 
when you boot the system. In all like- 
lihood, this will be the word-process- 
ing package, a CP/M-based version of 
MicroPro's acclaimed WordStar. The 
package contains two documents, the 
Word Processing Handbook and the 
Word Processing Applications and 
Reference Guide. 

The Handbook gives you a clear 
and almost painstakingly detailed ac- 
count of getting started. And it con- 



tains 15 tab-indexed pages of action 
and command summaries. But it does 
not tell you until page 43 that it is a 
good idea to make backup copies of 
your software disks. This is a simple 
process and is described on one of the 
tabbed pages at the back of the Hand- 
book. Perhaps the Handbook is in- 
tended for the casual user who will 
not be involved with the system be- 
yond using it as a word processor. 

The first information in the Appli- 
cations and Reference Guide is on mak- 
ing backup copies of software. In 
fact, the Guide is more complete in all 
respects. (One of the very first things 
you may want to do is run the diag- 




The new 820 Information Processor— it is a Xerox. (Photo courtesy of Xerox Corp./ 



nostic tests described in section 15.) 
Once you've booted the system, 
made backup disks and performed 
diagnostic tests, you're ready to start 
processing some words. If this is your 
first time, the Handbook should prove 
very helpful. If you have some expe- 
rience, you may need only the 
menus, and a help key that gives ex- 
tensive instructions. Menus (see 
Table 1 for the main menu) are 
displayed at the top of the screen. 
But, if you want, you can eliminate 
these and use the full screen for text 
display. 

Word processing features include: 

• Search— For searching forward or 
backward through a document 

• Find/Replace— To search for and 
replace a word any- or everywhere 
in an entire file, ignoring upper/lower 
case difference. 

•Auto bold— For titles and so on 

• Headers/trailers— For standard, 
multiline and alternating page head- 
ers and trailers 

•Wordwrap— To automatically 
move a word that does not fit within 
the margins of a line down to a new 
line 

• Copy/move— To move a block of 
text within a document or to a new 
document 

•Auto centering— To center a line 
between the left and right margins 
•Justification— To justify print to 
user-specified margins 

• Underscoring 
•Overstriking 

• Super/subscripts— To print a half 
line above or below the current 
typing line 

In the month or so that I've been 
using this package, I've been im- 
pressed by its power, versatility and 
ease of use. 

CP/M and Other Software 

If you intend to use the 820 for 
something else, you may want the 
CP/M package, which consists of the 
CP/M disk and two documents. CP/M 
opens many possibilities, since CP/M 
has virtually become a standard mi- 
crocomputer operating system. The 
casual user need know nothing about 
CP/M to use it to load and run any of 
the many commercially available 
CP/M-based programs. 

In addition to running programs 
under CP/M, the more knowledge- 
able user can modify or create new 
programs using CP/M features. These 
features are described in two docu- 
ments, CP/M Primer and the CP/M 
Manual. Neither was prepared by 



Brand-Name Shopping 



By James H. Nestor 



You don't realize how pervasive 
television is until you start to 
quote from TV commercials. I'm 
thinking of the one that features a 
series of salesmen trying to sell 
small office copy machines which 
are "just as good as a Xerox." The 
last salesman's final words are 
". . .it is a Xerox!" 

We have become a society of 
brand-name snobs. We buy an 
Oldsmobile instead of a Ford, and 
insist on Gloria Vanderbilt jeans. 
It is possible that many potential 
microcomputer users are waiting 
for an acceptable brand name to 
appear. As a consultant, I have 
met resistance from businessmen 
to buying a computer from Radio 
Shack or a company with a name 
such as Apple. What they seem to 
want is a name you can trust, 
something with a Fortune-500 ring 
to it. 

Another Microcomputer — 
So What? 

The Xerox 820 is certainly not 
the only new microcomputer on 
the market. I collected a huge 
stack of literature on new products 
at the National Computer Conven- 
tion in Chicago. With a few excep- 
tions, most of the new micros 
seem about the same. Aside from 
an occasional daydream about 
hard disks and remote terminals, I 
am content with my two-drive 
Radio Shack Model II and Daisy II 
printer. 

Still, I scan the new products an- 
noucements in several newsletters 
each week, looking for something 
truly new and exciting in the in- 
dustry. The announcement of the 
Xerox 820 caught my attention. 
The elements which aroused my 
interest were the name Xerox, and 
the price— $2995. 

Then I Met SAM 

When I arrived at the local Com- 



Address correspondence to James H. Nestor, 
MicroSohe, 39114 Route 303, Grafton, OH 
44044. 



puterland, I saw a colorful sign in 
the window inviting me to come in 
and "meet SAM." I learned that 
SAM stands for "simply amazing 
machine,' the nickname which 
Xerox has given to the 820. I also 
noticed that all of the literature 
refers to the unit as the 820 Infor- 
mation Processor. The term Infor- 
mation Processor suggests that the 
820 is not just a word processor, 
but a processor of words and data. 
In fact, SAM is a microcomputer, 
although that term is not used. 

The 820 uses a Z-80A micropro- 
cessor, and includes 64K of RAM 
and 4K of ROM. It has dual Sc- 
inch single-density drives, and a 24 
line by 80 character white-on- 
black display screen. The machine 
includes two parallel I/O ports for 
keyboard and disk drives, and two 
serial ports for printer and 
modem. 

The hardware is housed in three 
white cabinets. The display and 
keyboard cases are molded plastic 
with a pebble texture. The edges 
are nicely contoured. The disk 
drives are enclosed in a white 
metal cabinet. The power switch, 
reset button and display bright- 
ness control are all located be- 
neath the lower edge of the moni- 
tor case, and thus are safe from ac- 
cidental contact. The overall 
appearance is uncluttered and 
business-like. 

The rear apron is equally clean. 
There are only four connectors 
and an ac line cord. The connec- 
tors are for keyboard, disk drives, 
printer and modem. The connect- 
ing cables are similar in ap- 
pearance and size to RG-8 coax 
cable, and terminated with RS-232 
connectors. The ac power for the 
disk drives is supplied by the cable 
from the monitor, eliminating the 
need for another line cord. 

The keyboard can be moved 
about a foot from the monitor, a 
feature important in reducing 
fatigue. The keyboard, which re- 



(continued on p. 96) 



Microcomputing, December 1981 95 



1 

2 
3 
M 
5 
6 



MAIN MENU 
go to menu 
block menu 
document menu 
format (display) 
format (nondisplay) 
reformat papagraph 



HELP = 



7 = delete this line 

8 = insert line here 

9 = insert mode(on/off) 
= repeat next command 
= = scroll up line 

- = scroll down line 



E 
F 
G 
J 
K 
L 



for assistance 
change help level 

up screenful 
down screenful 



scroll 
scroll 
find 
find & 
repeat 



replace 

find & replace 



You may type now -or- give a command using CTRL + (any key shown above). 



Table 1. 



Xerox— the Primer is a Howard W. 
Sams book by Stephen Murtha and 
Mitchell Waite, and the Manual is 
almost entirely by Digital Research 
(producers of CP/M) r with a few in- 
sertions by Xerox about the 820. Both 
describe such CP/M features includ- 
ed in the Xerox 820 version as the 
editor, the assembler (actually, this is 
the Digital Research 8080 assembler) 
and the dynamic debugging tool, but 
the Manual does so in more detail and 
includes alteration and interface 
guides. In addition, the Manual con- 
tains a few system notes on the 820 
which will be helpful to the serious 
programmer. 
Other Xerox 820 software current- 



ly or soon to be available includes Mi- 
crosoft BASIC, CBASIC-II, an elec- 
tronic worksheet package (probably 
VisiCalc) and a telecommunications 
package. According to Xerox, "Ether- 
net compatibility is provided through 
the previously announced Xerox 872/ 
873 communications servers. The 820 
can also use the Xerox 871 interactive 
communications emulator for 3270- 
mode access to a host computer." 

Inside the 820 

The Xerox 820 is a single-board mi- 
crocomputer using the Z-80 processor 
(at 2.5 MHz) with 64K bytes of pro- 
grammable random-access memory 
(RAM) and 4K bytes of read-only 



(from p. 95) 

sembles an office typewriter key- 
board, has a comfortable feel. It in- 
cludes two control keys and a key 
labeled Help. 

A separate keypad includes nu- 
merals, decimal point, + , - , DEL 
(delete), ESC (escape), line feed 
and cursor control keys. 

A printer is not included but is 
necessary for any serious use. All 
of the literature refers to the 
Diablo 630 printer, which came 
with the system I tested. 

The Diablo 630 is bidirection- 
al, and types 40 characters per sec- 
ond. It uses either plastic or metal 
daisywheels. You can use either 
single sheets or buy an optional 
tractor feed. Its retail price is 
$2900. 

The System Software Is the 
Secret 

Many microcomputer manufac- 
turers, including IBM, DEC, Lan- 
ier and Honeywell, have chosen to 
sell both hardware and software. 
Consequently, they have limited 
the amount of available software. 
If the machine is dedicated to one 
purpose, such as word processing, 
the manufacturer's software may 
be adequate. But if the machine is 



to be used for other purposes, 
problems may arise. Software de- 
velopment is expensive and time- 
consuming. While software is be- 
ing written, the customer may find 
himself with little more than an 
expensive paperweight shaped 
like a computer. 

The 820 uses the CP/M 2.2 oper- 
ating system. Since only minor 
changes are needed to run the 
same program on a range of CP/M- 
equipped microcomputers, the 
SAM user has a wide range of soft- 
ware open to him. 

In addition to the CP/M soft- 
ware, the 820 package includes a 
diagnostic disk. A word processing 
program is a $495 option. Initially, 
Xerox will probably offer a limited 
selection of software. They are en- 
couraging independent software 
developers to write quality soft- 
ware, rather than produce all of 
the software themselves. 

First Comes Word Processing 

With the Diablo 630 printer, 
SAM makes a first-class word pro- 
cessing system for about $6300. 
This places it significantly below 
the price of the new word-process- 
ing systems from IBM, Wang, Lan- 

( continued on p. 98) 



YES! I'd like to give 
some time to a friend 
and subscriber. 

Gift of Time * 

$25 (5 hours Plus 1 FREE hour) 
$50 (10 hours Plus 2Va FREE hours) 
$100 (20 hours Plus 6 FREE hours) 



Number of 
Certificates 

$25 



Total Cost 



$50 



$100 



TOTAL 

The "Gift of Time" applies to our regular 
Information Service Network connect times 
between the hours of 6 PM to 5 AM local 
time weekdays and all day weekends at 
300 baud or less — and is not applicable to 
any purchase or surcharge costs. 

Buyer's Name: 



(Name) 



(Address) 



(City) 



(State) (Zip) 

Where a "Gift of Time" is being purchased 
for a friend, a certificate will be sent to you 
so it may personally be presented to the 
individual. 

Please check the appropriate box(s): 

□ I am a non-subscriber to the 
CompuServe Information Service. A 
check or money order for the "Gift of 
Time" Certificate is enclosed. 

□ I am a subscriber to the CompuServe 
Information Service. A check or money 
order for the "Gift of Time" is enclosed. 



□ This is a gift for a friend. 

□ This is a gift for myself. 
My user I.D. is as follows, 



Please make check or money order out to 
CompuServe Information Service. Gift 
Certificates must be redeemed by 
March 31, 1982. 



CompuServe 

Information Service Division 
5000 Arlington Centre Boulevard 
Columbus, Ohio 43220 



^ 147 



96 Microcomputing, December 1981 




IFOR NEW USERS. 
CompuServe is in the holiday 
mode. If you subscribe to our 
system for the first time in 
November or December, we'll give 
you two free hours of CompuServe 
access time instead of one. That's 
a $10 savings just to get started. 
So get thee to a Radio Shack 
Store®, get a demonstration, then 
buy the Videotex software package 
for most popular computers 
($29.95) or buy the system without 
software for "dumb" terminals 
($19.95). 

And . . . once you're a sub- 
scriber, you can clip the adjacent 
coupon and take advantage of our 
second "gift of time". Good deal? 
You bet! 



BASIC MENU 

• Electronic mail • Financial data 
& historical information • Special 
interest data • User newsletters 

• CB simulation • Newspapers 

• AP wire • Games • Plus, when 
you need it, languages, file cre- 
ation & storage (128K free!), soft- 
ware downloading, other services. 
Over 1 30 separate entries on the 
current menu. 



CompuServe 



^147 



IFOR CURRENT 
SUBSCRIBERS. 
You can give a friend and 
subscriber six hours or more 
connect time on CompuServe at 
a savings of 20 to 30% off the 
regular $5.00 per hour rate. See 
the adjacent coupon for actual gift 
certificate values. If you are your 
only friend with a computer or 
terminal, give yourself the gift. 
There will be lots of access time 
over the holidays, and these 
special low prices will let you or 
your friend connect with the 
fascinating world of the 
CompuServe Information Service 
at a substantial savings. 



Radio Shack is a trademark 
of Tandy Corporation. 



Information Service Division 
5000 Arlington Centre Boulevard 
Columbus, Ohio 43220 
(61 4) 457-8600 (800) 848-8990 



(from p. 96} 

ier and Honeywell. With a letter- 
quality printer, those systems 
range from $7500 to over $10,000. 

The word processing program is 
a variation of WordStar by Micro 
Pro. This is a good choice, since 
WordStar is considered by many 
to be the most powerful CP/M- 
based word processing software 
available. 

The version of WordStar for the 
SAM has been customized for the 
system. For example, the delete 
key deletes one character to the 
right, and the cursor arrows move 
the cursor on the screen. Holding a 
key down for more than a second 
or so causes that key to repeat. I 
suspect that this is a hardware 
feature, since it isn't included in 
other versions of WordStar. 

Pressing the Help key at any 
time produces instructions on the 
screen. Actually, it is a menu of 
menus, each with additional infor- 
mation about the program opera- 
tion. WordStar has an elaborate 
system of help menus already. The 



addition of a specific Help key 
adds to a feeling of confidence 
when using the system. I expect 
that future software for the SAM 
will make use of this key. This is a 
step toward making micros more 
friendly. 

The Manuals 

Three manuals are included. 
The system includes the CP/M 
manual. Unfortunately, the first 
several chapters are from Digital 
Research, the company which 
owns the rights to CP/M. These are 
among the most unreadable docu- 
ments I have encountered. The 
folks at Computerland had wisely 
inserted one of the newer guides to 
CP/M inside the binder. If Xerox 
must include the original CP/M 
documents, they might consider 
placing them in the back of the 
binder as an appendix. 

Three chapters are written spe- 
cifically for the SAM. The first ex- 
plains the system tests performed 
by the diagnostic disk. They in- 

( continued on next page) 



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memory (ROM). It provides 24 lines 
by 80 characters of memory-mapped 
video display. The 820 has a real-time 
clock, and uses the Western Digital 
1771 disk-controller chip for floppy- 
disk I/O. The two parallel ports are 
used for the keyboard and the Shu- 
gart-compatible disk drives. There 
are two RS-232 serial ports, one des- 
ignated for the optional printer and 
the other for communications. 

The board and the interfaces are 
located in the same unit as the 
12-inch black and white video dis- 
play. The 96-character ASCII key- 
board is a separate unit and includes 
a 20-key function and numeric pad. 
The standard 5Vi-inch single-density 
disk drives are in a third unit (option- 
al eight-inch drives are available). 

Even though I'm impressed with 
the overall performance of the 820, it 
seems that it could have been even 
better. For example, why does the 
microprocessor run at 2.5 instead of 4 
MHz, and why are single instead of 
double-density drives used? 

Cost 

The standard Xerox 820 system 
(console, keyboard and dual SVi-inch 
drives) sells for $2995. The system 
with the optional serial printer (the 
excellent letter-quality Diablo 630) 
costs $5895. Optional eight-inch disk 
drives go for an additional $800. 

The 820 is being sold at Xerox 
stores, and at additional retail outlets 
such as Computerland stores. 

Conclusions 

Xerox's new 820 Information Pro- 
cessor is not designed to be a home or 
hobbyist's computer. In fact, the 820 
is not nearly as impressive as some 
other personal computers, such as 
Xerox's own Star, which costs three 
to four times as much as the 820. 

Nevertheless, the 820 is a sound 
product that does what it was intend- 
ed to do for the user it was designed 
for. And though it may not be a very 
flashy system, probably more impor- 
tant is the fact that it's very comfort- 
able to use. 

Xerox has given no consideration 
to games, color or graphics. But the 
820 is a good choice for anyone who 
has to do a good deal of writing. A 
few 820 computers could be connect- 
ed via a local network to share re- 
sources or a common printer. 

The 820 is, as Xerox states, intend- 
ed to be a word processing and busi- 
ness applications work station. At 
that it is a success. ■ 



98 Microcomputing, December 1981 




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elude two memory tests, a screen 
display test, a disk read/write test 
and a printer test for the Diablo 
630. The chapter is well-written, 
illustrated and easy to follow. 
Properly used, the system tests 
should eliminate a few needless 
calls to the computer store. 

The second chapter presents the 
Diablo 630 printer in considerable 
detail. While it is not a service 
manual, it does explain how the 
printer works. It certainly con- 
tains enough understandable in- 
formation for the end user. 



The purchaser of the 820 

will be . . . 

a lawyer, a wholesaler, 

a CPA, a writer. 



The third chapter contains some 
24 pages of information about the 
820 Information Processor. It in- 
cludes a description of the system 
architecture, discusses the ROM 
monitor routines and lists ad- 
dresses for subroutines. There are 
even pin-out diagrams of the I/O 
ports. Xerox does not intend to 
keep any secrets about the SAM. 
The only thing I didn't see men- 
tioned was a description of the bus 
architecture. 

The word processing manual 
contains the same chapters on the 
630 and the 820 system, plus trou- 
bleshooting tips. Of course, it also 
includes information on operation 
of the word processing program. I 
didn't have time to examine this 
manual in detail, but it seems to be 
complete and readable. 

The third manual is a pocket 
guide to the word processing pro- 
gram. It includes self -instructional 
material and illustrations. The last 
15 pages or so are tab-indexed, and 
contain detailed instructions and 
examples. If, for example, you 
want to use boldface type, you can 
easily find the section on print 
enhancements in the index. This 
manual, combined with the help 
features, should make it easy for a 
new user to get started. 

Other Features 

When the machine is first turned 
on, the ROM monitor displays two 



options on the screen: 

A— Boot System 
T— Typewriter 

Typing A and pressing the re- 
turn key loads the system. The 
word processing disk automatical- 
ly loads and executes. In fact, you 
don't need to exit to the operating 
system; you can read the disk di- 
rectories, change disks and exe- 
cute CP/M utilities such as STAT 
or PIP directly from the program 
menu. 

The typewriter option is a ROM 
monitor function, and does not re- 
quire a disk in either drive. It per- 
mits the unit to function from key- 
board-to-printer, like a typewriter. 
Characters are not displayed on 
the monitor, but are printed 
directly on the printer. 

While the inclusion of the Type- 
writer mode does not seem like 
much, it shows an awareness of 
the day-to-day routine in most of- 
fices. Frequently, the installation 
of a word processor does not elimi- 
nate the need for a regular office 
typewriter. It is not only overkill, 
but downright awkward to use 
WordStar to address envelopes or 
type shipping labels. 

Who Is That Masked End-User? 

I have repeatedly referred to the 
SAM end-user. Who is he or she? 
My impression is that the average 
purchaser of the 820 Information 
Processor will not be a computer 
hobbyist, who can find the hard- 
ware and software features of the 
SAM in several other machines. 
The board-level tinkerer can 
duplicate the system for less 
money. The more serious hobbyist 
can find a selection of more pow- 
erful hardware. 

The purchaser of the 820 will be 
a business or professional person: 
a lawyer, a wholesaler, a CPA, a 
writer. He will be responsive to 
two things about the SAM: the 
brand name and the price. 

I also predict that the average 
end-user will find a lot to like. The 
user who has previous word pro- 
cessing experience will find that 
the 820 offers many large system 
features at a fraction of the price. 
The person who has never tried 
computerized word processing 
will be amazed. Personally, I 
broke all of my #2 pencils and 
turned my typewriter into a 



planter. 

What About Data Processing? 

The 820 is billed as a complete 
information processor. That in- 
cludes data as well as words. The 
system should function equally 
well in that area, based on the 
large number of CP/M programs 
available. The major limitation to 
serious data processing use is the 
limited amount of disk storage 
with the 5V4-inch drives. The 
CP/M operating system and word 
processing program, for example, 
occupy all but 9K bytes of the 
space on the first disk drive. That 
means that there is only 90K of 
data storage on the second drive. 
For all but the smallest operations, 
that is not enough. 

There is, however, an option to 
replace the dual 5%-inch drive 
with dual eight-inch drives. Using 
single-sided, single-density for- 



The fact that the new 820 

is a Xerox product 

may be its 

most important feature. 



matting, that yields about 300K 
per drive, sufficient space for such 
software as the Peachtree account- 
ing packages. 

Conclusions 

It would seem that Xerox does 
not intend the 820 Information 
Processor to be the ultimate micro- 
computer. Rather, they see it as an 
affordable system for the entry- 
level user. It can also be an inex- 
pensive component in a very com- 
plex and powerful automated of- 
fice environment. The fact that the 
new 820 is a Xerox product may 
be its most important feature. 

Certainly, some of the present 
micro manufacturers will resent 
the intrusion. Those of us with a 
broader perspective (and less 
capital invested) will welcome 
Xerox to the industry. The more 
systems sold, the more potential 
customers for software and ser- 
vices. And the more the public 
becomes aware of the importance 
of the microcomputer, the greater 
its impact on society. ■ 



100 Microcomputing, December 1981 



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HEATH/ZENITH 



Your strong partner 



You, too, may achieve enlightenment if you use this programming technique 

to tackle seemingly insolvable puzzles. 



Recursion: Solving 

Age^Old Mysteries 



By Doug MacDonald 



A thousand years ago, so the story 
goes, members of a sect of Bud- 
dhist monks were required to solve a 
strange puzzle on their long road to 
enlightenment. 

Three diamond needles were 
mounted on a platform of brass. On 
one of these needles were stacked as 
many as 64 golden disks of decreas- 
ing size. The monks had to figure a 
way to move all the disks, one at a 
time, from the first needle to the 
third. The middle needle could be 
used to temporarily stack disks, but 
at no time could a larger disk be 
placed on top of a smaller disk. 

Had these monks owned a modern 
digital computer— assuming the mo- 
nastic powers would allow such de- 
vices on the premises— they could 
have used recursion to solve this 
problem in a snap. 

The Towers of Hanoi problem, as 
the disk-moving puzzle has since be- 
come known, is a textbook example 
of this unique mathematical and pro- 
gramming technique called recursion. 

A Definition 

In classic terms, recursion means 
defining a problem or its solution in 
terms of itself. In programming, a re- 
cursive routine is one which calls it- 
self—often over and over again. 

To the novice, this seems like an 



Address correspondence to Doug MacDonald, 
Coast Projects Ltd., 124 Kingston St., Victoria, 
B.C., Canada V8V 1V4. 



104 Microcomputing, December 1981 




outrageous form of cheating, a sort of 
algorithmic lifting yourself up by 
your own bootstraps. The program- 
mer trying to understand a recursive 
procedure is more likely to see it as 
ancient Chinese nested boxes— boxes 
within boxes within boxes. Or per- 
haps as the Oriental snake devouring 
its own tail. 



However mind-boggling, recursion 
allows elegant solutions to certain 
types of programming problems that 
would be awkward to solve by other 
means, and so it deserves some 
study. A number of high-level lan- 
guages, such as Pascal, LISP and 
Logo, makes special provisions for 
use of recursive techniques. 



But before discussing program- 
ming examples, let's examine the 
process of recursion itself and see 
how it works. 

Simplifying the Problem 

The idea is to reduce the complexi- 
ty of a problem by restating the prob- 
lem in terms of itself, but with sim- 
pler conditions, until you reach a triv- 
ial and easily solved case of the origi- 
nal problem. 

Take an example from mathemat- 
ics. The factorial of an integer 
n— written n!— is defined as the num- 
ber multiplied by all the integers be- 
low it down to 1. Thus, 4 factorial is 4 
times 3 times 2 times 1. Factorials 
find wide use in statistics and other 
math fields. 

The recursive way to look at factor- 
ials is to note that n factorial is equal 
to n*(n-l)factorial. And (n- ^fac- 
torial, of course, equals (n- l)*(n-2) 
factorial. This redefinition continues 
until you reach the trivial case of 
(O)factorial, which is defined as 1. 

Suppose you want to write a proce- 
dure to calculate the factorial of a giv- 
en input N. In Pascal, for example, 
you might write a program such as 
that in Listing 1. This program re- 
quests a number to be input for N, 
then calculates N! and prints the 
result. 

The actual calculation is performed 
by the recursive FACTCALC func- 
tion. The value of N is passed to this 
procedure where it is first tested to 
see if it is equal to zero. If it is not, the 
value is passed to the next line which 
multiplies N times N- 1 times N-2, 
etc., until zero is reached. This is 
accomplished by the procedure call- 
ing itself from within itself (FACT- 
CALC: = N * FACTCALCjN - 1 ) ) . The 
procedure calls itself with the value 
of N decremented by one each time 
until N is zero. When N is zero the 
value of FACTCALC (i.e., N!) is 
printed. 

Another example of a factorial pro- 
cedure written in a language de- 
signed to directly handle recursion is 
given in Listing 2. This listing, in the 
Logo programming language, actual- 
ly contains two procedures. The first 
calculates and prints the value of N!. 
The second procedure (READNUM- 
BER) requests a number to be input, 
calls the first procedure and passes it 
the value input. 

The first procedure (TO FACTOR- 
IAL :N :Q) calculates the factorial of 
input N. Input Q (which must be 
entered as 1) holds the values being 



calculated and at the end has the 
value of N!. (This procedure uses a 
slightly different factorial algorithm 
than that used by the Pascal program. 
The algorithm used here performs 
two multiplications at each level 
rather than one, reducing the number 
of times the procedure calls itself.) 

The FACTORIAL procedure takes 
the value of N and tests to see if it is 
less than two. If N is two or greater, 
the procedure multiplies Q (one) by 
N by N - 1 and gives this new value to 
Q. The procedure then calls itself, but 
this time with input N-2 instead of 
N and the new value of Q instead of 
one. It again tests the input to see if it 
is less than two. If it is, it prints the 
value of N! and stops. If the input is 
not less than two, the procedure con- 
tinues calculating and calling itself 
until it is, and then it prints the result. 

By now you're probably saying, 
"Never mind this Chinese boxes busi- 
ness; I could do the same thing just as 
well with a simple loop." Granted, 
many problems that can be solved 
with recursion are also suited to itera- 
tive techniques. However, observe 
that the above examples require no 
programming overhead of setting up 
and decrementing loop counters, sav- 
ing partial products and so on. The in- 
tent is clear, and the expression is 
elegant. 

Another example for mathematics 
might be the business of raising a 
number to a power. Many microcom- 
puter languages do not provide an ex- 
ponential instruction, leaving the 
programmer to write his own. 

So, instead of seeing N x as 
N*N*N*N . . . , you might observe 
that Nx = N*N(x-i). Continuing to 
redefine, you would eventually reach 
the case where x = 1, and N x is simply 
N. A recursive subroutine to do the 
job would contain a statement like: 

NPOWER = N*NPOWER(N- 1) 

Here again, a looping procedure 
could be worked out, but the recur- 
sive solution is clear and simple. 

Other Uses 

The above examples are trivial. 
More complex tasks, such as travers- 
ing a tree structure or calculating cer- 
tain types of polynomials, are often 
visible to the algorithm designer only 
in terms of recursion. 

In a nonmathematical field, sup- 
pose you wanted to derive a clear set 
of grammatical rules for the English 
language (or any language, including 
computer languages). 

One much-used method of expres- 



MAIN 
PROGRAM 



(0 



CALL TO 



"A" 



">V 



(if 





"A" 










"B" 




RETURN (i ) 






RETURN (ii) 
CALL TO "A" 

RETURN 


► 


X'X*4 

CONDITIONAL 
CALL TO "B" 

RETURN 




K 


/ 


» 






_y 


— dii) 


) 


J 


< 











Fig. 1. Subroutine recursion. 

sing language "grammars" is the 
Backus-Naur form (BNF). Each term 
or element of the grammar to be 
defined is followed by the symbol 
(:: = ), which is read as "is composed 
of, ' ' plus a list of all possible subcate- 
gories of that term. 

For instance, your English gram- 
mar might start: 

SENTENCE :: = SUBJECT PREDICATE 

meaning a sentence must contain two 
other grammatical forms called sub- 
ject and predicate. You would then 
proceed to further break down these 
terms: 

SUBJECT :: = NOUN|NOUN SUBJECT 

Here you are saying that a subject is 
composed of a noun or a noun and a 
subject. (The vertical bar means "or.") 

You'll notice that the definition of 
subject contains a reference to sub- 
ject—exactly what is being defined! 
This is a recursive definition, and 
it is one which appears quite often 
in BNF. 

The above example is a bit of a 
mind- twister at first glance, but in the 
end it's an efficient way of specifying 
that a subject may contain any num- 
ber of nouns— such as "Fred and Har- 
ry and Peter and " (The "and" 

would also have to be accounted for 
in the grammar, usually by a part of 
speech called a determiner.) 

Recursion has played an important 
role in recent advances by linguists, 
as well as in the field of computer 
language design. As mentioned earli- 
er, a number of high-level languages 
allow recursive techniques. LISP, the 
list processing language, is almost en- 
tirely composed of recursive state- 
ments. Others, such as FORTRAN 
and COBOL, do not provide for 
recursion. 

Recursion for the Millions 

But what about the microcomputer 
hobbyist? What use can he or she 
make of recursion? 

Microcomputing, December 1981 105 



Surprisingly enough, most garden- 
variety BASIC interpreters allow a 
sort of recursion— although not inten- 
tionally. And with a little care, you 
can even program recursively at the 
machine-language level. 



The majoi >blems. . . 
are what to do with 
tl irrent value of variable 
and . . . multiple return point 



I should mention that the above 
routines are examples of direct recur- 
sion. A further wrinkle can be added 
with indirect recursion. 

Here the main program calls a sub- 
routine—call it A— which calls a sec- 
ond subroutine, B. In turn, B makes a 
call back to A. The effect is still one of 
subroutine A calling itself; it just 
makes an extra step in doing so. Even 
more obscure would be subroutine A 
calling subroutine B, which calls 
subroutine C, which calls subroutine 
A; but this level of the snake eating its 
own tail is seldom seen. 

The BASIC program in Listing 3 
does exactly the same job as the Pas- 
cal and Logo programs and it uses the 
same algorithm shown in the Logo 
procedure. It is interesting to note 
that this program will run on vir- 
tually any computer with a BASIC in- 
terpreter capable of handling 
IF . . . THEN and GOSUB statements. 

(Note: We tried the program in Listing 
3 on a number of computers and it ran 
on every one, although on a few it was 
necessary to slightly modify lines 10 and 
1000, which have nothing to do with the 
recursive character of the program. 
Commodore's VIC 20 with only 4K 
bytes of memory could calculate up to 
23! before running out of memory. No 
other machine had memory problems, 
but they all had numeric overflow dif- 
ficulties at one point or another. Most 
(Apple, PET and TRS-80) could handle 
numbers up through 33!, which isn't bad 
considering that 33! is about 8,683, 
31 7, 61 8, 811,886, 000, 000, 000, 000, 
000, 000, 000. The North Star Horizon 
went up to 49!. But if you feel some com- 
pulsion for calculating factorials on a 
personal computer, you will want to 
take a look at the Atari 800 or the TI 
99/4A. The Atari could calculate 68!, 



and the TI with Extended BASIC when 
through 69!.) 

The program along with the algo- 
rithm it uses is elegantly simple. 
(One word of caution: Be very careful 
of using GOSUB statements without 
corresponding RETURN statements. 
It usually won't work.) Line 10 asked 
for the number whose factorial you 
want to determine. Line 20 just sets 
the value of Q at one. The variable Q 
will represent the value of N!, and 0! 
and 1! both equal one. 

The program then drops into the 
recursive subroutine (lines 500 
through 530). First the value of N is 
tested. If it is less than two, the pro- 
gram goes to line 1000, which prints 
the result (in this case N! = l) and 
ends the program. (The END in line 
1000 could be changed to GOTO 10 if 
you absolutely have to find more 
than one factorial per sitting.) 

If the value of N is two or larger, 
the program drops to line 510, which 
sets a new value of Q equal to the old 
Q (still one) times N times N - 1. Line 
520 sets the value of N at the original 
value minus two, and line 530 sends 
this back to line 500. If N is now less 
than two, the result is printed; if not, a 
new value for Q is determined to the 
value of Q from the last round times 
the new value of N (the original value 
less two) times the new N minus one. 
N is now set to be two less than the 
value of N from the last round. The 
program again returns to line 500 and 
this newest value of N is tested. This 
continues until the value of N is less 
than two (0 or 1), at which time the 
final result is printed. 

Line 530 of the subroutine func- 
tions something like the recursive 
calls in the Pascal and Logo pro- 
cedures. This line calls the subrou- 
tine from within itself. 

Problems 

The stack is the key to recursion. 
Here, microcomputers have the ad- 
vantage over some mainframe ma- 
chines that do not have a hardware 
stack. 

Why is the stack important? The 
major problems with handling recur- 
sive subroutines, which will call 
themselves an unknown number of 
times, are what to do with the current 
value of variables and how to keep 
track of multiple return points. 

Consider Fig. 1, which shows a 
case of double recursion. The main 
program at some points makes a call 
to subroutine A. Assume for the mo- 
ment that there is no stack in this par- 



ticular machine; that a subroutine 
has within it a memory location to 
hold the return point, where it is sup- 
posed to return control after comple- 
tion. Subroutine A then saves (i) as 
the location in the main calling pro- 
gram to which it will return control. 

As it is executing, subroutine A en- 
counters a call to subroutine B. As 
necessary, B stores (ii) as its return 
point back to A. 

But now B makes a recursive call 
back to A. This time, subroutine A, 
not knowing that it has already been 
called once without completing its 
run, dutifully stores (iii) as its return 
point. Eventually, it returns to (iii) in 
B. Subroutine B continues until 
reaching its return instruction and 
passes control, as it should, to (ii). So 
far so good. 

Then subroutine A completes its 
execution. But, instead of going back 
to (i) where it should, it passes control 
back to (iii) in subroutine B, which 
was the last return point stored. It's 
easy to see that there's an endless 
loop here, with control flickering 
back and forth between A and B, 
while you, the programmer, sit 
wondering just what went wrong. 

Another problem arises with vari- 
ables in a recursive routine. Look 
again at Fig. 1. Imagine that in A 
there is the assignment statement 
X = X + 4. Presumably, the main call- 
ing program wants just this action: 
for X to be returned four larger than 
it was. However, when A calls B, 
which in turn calls A again, the state- 
ment will be executed at least one ex- 
tra time. So when A eventually 
passes control back to the main rou- 
tine, X will actually be at least eight 
larger. This type of problem is ex- 
tremely tough to track down. 

The hardware stack is the natural 
way to solve the return point prob- 
lem. Both machine and higher-level 



MAIN CALL 
TO "A M 


A" CALLS 
B" 


I 

I 


B" CALLS 
A" 


o 




L^ 




o 




( i ) 


(i ) 


111 




(it) 


t.n 






tun 






1 , 













"A" RETURNS 
TO "B" 



"B" RETURNS 
TO "A" 



"A" RETURNS 
TO MAIN 



O 



Ii ) 



■m 



mn. 



o 



<i ) 

HIE 



o 



(i ) 



Fig. 2. Stacks shown throughout the sequence of 
recursive calls. 



106 Microcomputing, December 1981 



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Some people have a talent for recursion, but most 
of us count on fingers and toes. 



language call. . . return sequences use 
the stack to push down the return 
point. If a subroutine encounters 
more than one call before comple- 
tion, the extra return points are sim- 
ply pushed down on top of the previ- 
ous ones; during the sequence of 
returns, these addresses are popped 
off the stack in reverse order— just 
the order needed. 

Fig. 2 shows the stack throughout 
the sequence of recursive calls just 
discussed in relation to Fig. 1 . The ar- 
row indicates the stack pointer loca- 



tion (assume that the stack grows 
downwards). The last-in, first-out na- 
ture of the stack lets it keep perfect 
track of just who should pass control 
to whom and when. 

The way to avoid unexpected loss 
or overwriting of variables— side ef- 
fects—in recursive routines is to en- 
sure that the routine will keep sepa- 
rate copies of the values for each in- 
vocation. This can be done with ar- 
rays, or use the stack to push tempo- 
rary values, being careful not to de- 
stroy return points. 



PROGRAM FACTORIAL; 
VAR N : REAL; 
FUNCTION FACTCALC (N : REAL) : REAL; 
BEGIN 
IF N = THEN FACTCALC: = 1 
ELSE FACTCALC: = N*FACTCALC(N- 1) 

END; 
BEGIN (*MAIN PROGRAM*) 
WRITE (FACTORIAL (N!) OF '); 
READLN (N); 
WRITELN ('N! = \FACTCALC(N)) 

END. 



Listing 1. A factorial program written in Pascal The main program asks for a value ofN to be in- 
put and then prints the value ofN!. The value ofN! is calculated by calling the recursive function 
FACTCALC and passing it the value ofN. This subroutine determines N! by testing whether or not 
N is zero. If not, it sets the value of FACTCALC at N times the value ofFACTCALCfN- 1), which 
is the factorial ofN- 1. This means it is necessary to back through FACTCALC again and again un- 
til N equals 0, at which point FACTCALC equals N! and the main program prints that value. 



TO FACTORIAL :N :Q 

IF :N<2 THEN PRINT1 "N!= PRINT :Q STOP 

MAKE "Q:Q*N*(N-1| 

FACTORIALS -2 :Q 
END 

TO READNUMBER 

PRINT1 SENTENCE [FACTORIAL (N!) OF] [] 

MAKE "INPUT FIRST REQUEST 

IF NUMBER? :INPUT THEN FACTORIAL :INPUT 1 
END 



Listing 2. A Logo version of a factorial program. The READNUMBER procedure (thanks to Hal 
Abelson of MIT's Logo Project) works something like the main program in Pascal. It requests a 
value for N, then calls the FACTORIAL procedure and passes it the value input for N and one for 
Q. FACTORIAL tests the value of N and, if it is less than two, prints one for the value of N! and 
halts. IfN is two or larger, the procedure changes the value ofQ from one to Q (i.e., one) times N 
times N- 1. The procedure then calls itself, but now inputs N - 2 instead ofN and the new value of 
Q instead of one. This continues over and over until N is less than two and the result is printed. 



10 INPUT "FACTORIAL (N!) OF "; N 

20Q=1 

500 IF N<2 THEN GOSUB 1000 

510Q=Q*N*(N-1) 

520N = N-2 

530 GOSUB 500 

1000 PRINT "N! = ";Q: END 

Listing 3. A BASIC factorial program. This pro- 
gram, like the others, contains a recursive 
routine (lines 500 through 530) which deter- 
mines the factorial of an input number N. 



108 Microcomputing, December 1981 



Conclusions 

What do you look for in picking out 
computer tasks that are amenable to 
recursive solution? There are no hard 
and fast guidelines. Some people 
seem to have a native talent for seeing 
recursion, an intuitive understanding 
of its intricacies. Most of us, though, 
have to struggle through, scribbling 
state diagrams and counting on fin- 
gers and toes. 

Basically, any task that requires 
summing or a series expansion is a 
prime candidate. Calculus functions 
with a parameter approaching zero or 
infinity can sometimes be handled 
nicely with recursion. Any subrou- 
tine that is called in a regular, repeti- 
tive way should be looked at with the 
idea of getting the routine to call itself 
until its task is done. 

One typical student programming 
problem is to write a routine that will 
list all possible combinations of 
change from a dollar. A pleasing way 
to solve this problem is to use a sub- 
routine which, for any given coin 
value, calculates the number of times 
this coin will fit in the change need- 
ed, set the remainder as the new 
change value and have the routine 
call itself with the next lower value of 
coin. This might be an interesting ex- 
periment to test your BASIC interpre- 
ter' s recursive capabilities, but don't 
be disappointed if stack overflow 
causes your computer to freeze up. 

Now that you have a basic under- 
standing of recursion, you might like 
to get one up on the Buddhist monks 
and solve the Towers of Hanoi prob- 
lem. I won't tell you how it's done, 
but I'll give you a hint. Don't think 
about the top disk on the first needle, 
which will be one you would move 
first. Think about the trivial case of 
moving the bottom disk from needle 
1 to needle 3 and proceed from there. 

May you achieve enlightenment! ■ 

Reader Service for facing page ^409-* 




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Instant Software 



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*TRS-80 is a trademark of Radio Shack a division of Tandy Corporation 
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ALAtAMA 

THE COMPUTER SHOP. Gadsden 

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COMPUTER TALK, Anchorage 

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ARIZONA 

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PC COMPUTERS. El Cerrito 

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SOFTWARE PLUS, El Toro 

STACEY'S BOOKSTORE, San Francisco 

STRAWFLOWER ELECTRONICS (R/S DEALER). 

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Manchester 

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DISTRICT OF COLUMBIA 

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FLORIDA 

ADVENTURE INTERNATIONAL, Casselberry 

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TRI-COUNTY ELECTRONICS & SOUND 

CENTER. Fenton 

WEATHERWAX DRUGS. Brooklyn 

WIZARD S ARSENAL, East Lansing 

YE OLDE TEACHERS SHOPPE. Ypsllanti 



MINNESOTA 

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Portsmouth 

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STURDIVANT AND DUNN. Conway 

NEW JERSEY 

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LASHEN ELECTRONICS. INC.. Denville 
MIDAS DATA SYSTEMS INC.. Marlton 
OMNIFAX, Cherry Hill 

RADIO SHACK ASSOC. STORE, Moorestown 
RADIOS UNLIMITED. Somerset 
SOFTWARE CITY, River Edge 

NEW MEXICO 

AUTEL ELECTRONICS CO . Albuquerque 

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MITCHELL MUSIC. Carlsbad 

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WARGAMES WEST. Albuquerque 

NEW YORK 

ARISTO CRAFT DISTINCTIVE MINIATURES, 

New York 

ASD HOME COMPUTER CENTER, 

Poughkeepsie 

BERLINER COMPUTER CENTER, 

New Hyde Park 

C. HABILD OF NEW DORP. Staten Island 

COMPUTER CORNER, White Plains 

COMPUTER RESOURCES. Williamsvllle 

COMPUTER SHOP, Kingston 

COMPUTERLAND, Carte Place 

COMPUTERLAND OF NYC, New York 

DIGIBYTE SYSTEMS. New York 

80-MICROCOMPUTER SERVICES. Cohoes 

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PHANTOS RESEARCH. Camillus 

PROGRAMS UNLIMITED. Jericho 

MR. COMPUTER, Wappingers Falls 

OMNIFAX. DeWItt 

SOFTRON SYSTEMS, Rensselaer 

WATERLOO HOBBIES. Mineola 

WORLD OF COMPUTERS. Port Chester 

NORTH CAROLINA 

RAYBURN MICRO-ELECTRONICS. Sytva 

SOUND MILL. Havelock 

OHIO 

ABACUS li. Toledo 

ALTAIR SYSTEMS, INC.. Dayton 

ASTRO VIDEO ELECTRONICS, INC , Lancaster 

CINCINNATI COMPUTER STORE. Cincinnati 

COMPUTER STORE, Toledo 

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MICRO ELECTRONICS INC.. Columbus 

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TWENTY-FIRST CENTURY SHOP, Cincinnati 

WANNA PLAY. Cincinnati 

OKLAHOMA 

COMPUTER STORE. INC., Tulsa 

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OREGON 

COMPUTER PATHWAYS. Salem 

L&R ELECTRONICS, Grant Pass 

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TRS-SO PRODUCTS LTD , Portland 

PENNSYLVANIA 

ALLIED HOBBIES. Philadelphia 

ARTCO ELECTRONICS. Kingston 

BELL ELECTRONICS. Girard 

COMPUTERLAND. Gibsonla 

COMPUTERLAND OF HARRISBURG. 

Mechanicsburg 

ERIE COMPUTER. Erie 

JNE COMMUNICATIONS. Altoona 

MAFEX ASSOCIATES. Johnstown 

OMNIFAX. Feasterville 

OMNIFAX, Philadelphia 

PERSONAL COMPUTER CORP . Padi 

PITTSBURG COMPUTER STORE, Pittsburg 

STEVENS RADIO SHACK DEALER, Phoenuviile 

ROUTE 30 ELECTRONICS, Latrobe 

RUMPELSTILSKIN TOY SHOP, New Hope 

TELEVISION PARTS COMPANY INC., 

New Brighton 

PUERTO RICO 

MICRO COMPUTER STORE, Caparra Terrace 

RHODE ISLAND 

COLONIAL ENTERPRISES. Foster 

SOUTH CAROUNA 

OMNI ELECTRONICS. Charleston 

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ACE MINI SYSTEMS. Ciarksviite 

CHATTANOOGA COMPUTER CENTER. 

Chattanooga 

COMPUTER WORLD. Nashville 

COMPUTERLAB. Memphis 

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CODEOATA INC.. Arlington 

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COMPUSHOP/FM 1960W, Houston 

COMPUSHOP/N FWY, Houston 

COMPUTER N THINGS. Austin 

COMPUTER PROGRAMMING ASSOC . Lubbock 

COMPUTER PORT, Arlington 

COMPUTER SALES & SERVICE, Fort Worth 

COMPUTER SOLUTIONS, San Antonio 

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COMPUTERS BY O NEILL. Lake Jackson 

COMPUTERS TO GO, Austin 

COMPUTEX. Webster 

CORSAIR, Ft. Worth 

GATEWAY ELECTRONICS, Houston 

KA ELECTRONICS. Dallas 

MACS TV. Fairfield 

MARYMAC INDUSTRIES (R/S DEALER). 

Houston 

PAN AMERICAN ELECTRONICS (R/S DEALER), 

Mission 

R.L. COLE'S ELECTRONICS. San Antonio 

ROY'S CB & ELECTRONICS. Aransas Pass 

80 SOFTWARE. San Antonio 

WAGHALTER BOOKS. INC , Houston 

UTAH 

COMPUTERLAND. Salt Lake City 

FOOTHILL MODELERS. Salt Lake City 

VIRGINIA 

COMPUTER SOLUTIONS, Leesburg 

COMPUTER WORKS. INC , Harnaonburg 

HOME COMPUTER CENTER INC . 

Virginia Beach 

LITTLE SOLDIER. Alexandria 

SYSTEMS MARKETING. Arlington 

WASHINGTON 

AMERICAN MERCANTILE COMPANY, Seattle 

COMPUTERLAND. Beilevue 

COMPUTERLAND, Federal Way 

COMPUTERLAND. Spokane 

EMPIRE ELECTRONICS. Sunnyside 

J.B. SALES. Snohomoish 

LORDS. Port Angeles 

UNIVERSITY VILLAGE MUSIC, Seattle 

U S.S. ENTERPRISE. Kirkland 

WESTERN MICROCOMPUTER CENTER, 

Beillngham 

WEST VIRGINIA 

COMPUTER CORNER, Morgantown 

COMPUTER STORE. Huntington 



OHIO VALLEY ELECTRONIC SYSTEMS. 

Wheeling 

SOUND A ELECTRONIC SPECIALTIES. 

Morgantown 

WISCONSIN 

BYTE SHOP, Milwaukee 

COMPUTERLAND, Madison 

COMPUTERLAND OF FOX RIVER VALLEY. 

Oshkosh 

COMPUTER WORLD. Green Bay 

MAGIC LANTERN COMPUTER, Madison 

OMEGA MICROS, Milwaukee 

PETTED MICROSYSTEMS, Milwaukee 

SAO TV SALES, Monroe 

WYOMING 

COMPUTER CONCEPTS, Cheyenne 

AUSTRALIA 

DE FOREST SOFTWARE. Nunawading. Vic. 
CANADA 



Distributor: 

MICRON DISTRIBUTING, 

Toronto, Ont 



ALLIED COMPUTER CENTRE. Thunder Bay. 

Ontario 

ARKON ELECTRONICS, Toronto. Ontario 

AULL COMPUTER SYSTEMS, Victoria. B.C. 

BITS & BYTES. Dartmouth, N.S 

CENTRAL DISTRIBUTORS LTD , Lachine, 

Quebec 

COMPUCORNER, Smithers, B C 

COMPUMART, Ottawa. Ontario 

COMPUTER BARN, Sarnia. Ontario 

COMPUTER CIRCUIT. London, Ontario 

COMPUTER INNOVATIONS, Ottawa. Ontario 

COMPUTER SHOP LTD . Calgary, Alberta 

COMPUTER WORLD, Vancouver. B.C. 

COMPUTERLAND OF BURLINGTON. 

Burlington. Ontario 

CREATIVE COMPUTERS. Victoria. B.C. 

DATATEC COMPUTER SYSTEMS LTD., 

Saskatoon, Sask. 

ELECTRONICS 2001. Willowdaie. Ontario 

GALACTICA COMPUTERS LTD . Edmonton. 

Alberta 

IRISCO DU QUEBEC, Ste. Foy, Quebec 

LYONS LOGIC LTD.. London, Ontario 

MICROMATION. Toronto, Ontario 

MICROSHACK, Saskatoon. Sask. 

MICRO SHACK. Regina. Sask 

M&W COMPUTERS, Mississauga. Ontario 

NIP & TUCK VARIETY. London. Ontario 

OFFICE CENTRE, Kingston, Ontario 

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Ontario 

STATUS COMPUTER SYSTEMS, St. Catherines, 

Ontario 

TOTAL COMPUTER SYSTEMS. Ajax. Ontario 

WEST WORLD COMPUTERS. Edmonton, 

Alberta 

ITALY 

BITS & BYTES. Milan 

NEW ZEALAND 

VISCOUNT ELECTRONICS, Palmerston North 

NORWAY 

A/S SORLUNO. Vedsvagen 

SWEDEN 

SENTEC AB. Jarlaiia 

UNITED KINGDOM 

CALISTO COMPUTERS. Birmingham 

THE SOFTWARE HOUSE. London 

WEST GERMANY 

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NETHERLANDS A BELGIUM 



Distributor: 

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Eindhoven, Netn 



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MICRO OYNAMICS, Eindhoven 

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OVEL GONNE, Orachten 

RAL MICROCOMPUTERS. The Hague 



YOUR NAME COULD 

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Find out what you're missing. 

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Peterborough, N.H. 03458 603-924-7296 A18 



Here's an Applesoft utility that removes remark statements and thus frees up memory storage space and 

improves program execution speed without destroying program documentation. 



Stamp Out REMs 



By Paul Hitchcock 



If you're a whiz at structured pro- 
gramming techniques and possess 
total recall as well, you probably 
don't need to use remark statements 
to help document your BASIC pro- 
grams: everything is always logically 
ordered and details are never forgot- 
ten. On the ther hand, I usually use 
a great many of them, since I often 
can't remember where to find my 
Apple's on-off switch. 

But for all their usefulness in pro- 
gram documentation, REM state- 
ments have two not-so-useful charac- 
teristics: they consume memory and 



they reduce program execution speed. 

One obvious solution to these prob- 
lems is to file fully-documented back- 
up copies of your programs, but have 
versions without REM statements on 
hand for everyday use. However, 
should you become hazy about the 
inner workings of a program and find 
that you've misplaced your back-up, 
you can spend literally hours of pain- 
ful drudgery stepping through a long 
program in search of lost knowledge. 

Another more reliable solution is to 
use the REM-mover program given in 
Listing 1. With this short machine- 



Name 


Address 


Function 


INIT 


300-308 


Initialize next statement 
pointer to 801 


EOP 


309-320 


Check for end of program; 
get next address 


REMCH 


321-328 


Check for REM statement 


NOREM 


329-333 


Get next statement; jump to 
EOP 


REM 


334-33A 


Save address in stack 




33B-340 


Calculate offset 


SHIFT 


341-35E 


Shift BASIC program to 
cover REM statement 


SETPT 


35F-372 


Set Applesoft pointers 


ADJST 


379-3BB 


Adjust next-statement 
pointer bytes; get next ad- 
dress; jump to EOP 


REM-mover uses five zero page memory locations: 06 through 09 and 19. Registers 06 and 07 


hold the address of the BASIC 


program statement that REM-mover is currently examining; 


registers 08 and 09 contain the address of the next statement. Register 19 holds the "offset 


number,'' as was mentioned in 


the text of the article. 




Table 1. REM-mover routines. 



language program, you can quickly 
eliminate REM statements from a 
previously loaded Applesoft program 
using only a single keyboard-issued 
command. You thus gain all of the 
speed and space advantages of pro- 
grams without REM statements, but 
your on-line programs can be iden- 
tical to your back-up copies; should 
you lose either one, you do not lose 
the essential documentation. 

Entering and Using REM-Mover 

The REM-mover program will 
work only with Applesoft in ROM; it 
will not work with cassette Applesoft, 
diskette Applesoft or Integer BASIC. 
REM-mover' s single limitation is that 
it can remove only those REM state- 
ments which begin with statement 
numbers; it will not remove a REM 
which comes at the end of another 
program statement. 

You may enter the program as 
shown in Listing 1 using the Apple's 
mini-assembler, but it would proba- 
bly be easier to use the hex dump in 
Listing 2. Enter the monitor with 
CALL- 151 and type in each line as 
shown, remembering to change the 
dash after each address to a colon. 
When you have finished, carefully 
check your work. Since REM-mover 



112 Microcomputing, December 1981 



Address correspondence to Paul Hitchcock, 2309 
Blake St., 0308, Berkeley, CA 94704. 



■^-Reader Service for facing page ^405 



accesses several of Applesoft's more 
sensitive areas, a typing error when 
entering the program could cause 
your Apple to hang when you first at- 
tempt to use REM-mover. To resume 
normal operation, you would then 
have to turn your computer off, then 
on again, thereby erasing any pro- 
gram you had in memory. 

To save the program on cassette, use 
the monitor command "300. 3BBW 
(return)", making sure that your 
recorder is running before pressing 
the return key. You can save REM- 
mover on disk with the DOS com- 
mand "BSAVE REM-MOVER, 
A$300, L$BB (return)". 

Using REM-mover is simple: Load 
an Applesoft program that contains 
REM statements and remove the 
REMs by typing 

(from BASIC) CALL 768 (return) 

(from the monitor) 300G (return) 

When you list your program, you'll 
find that all of the REM statements 
have vanished, leaving you with a 
shorter and faster-running program. 
Listing 3 demonstrates REM removal 
and also shows how REMs can ad- 
versely affect program speed. 

One word of caution: If your pro- 
gram contains any GOTO or GOSUB 
statements which reference REM 
statements, you must change the 
branching addresses to ensure error- 
free program operation after you 
have removed the REMs. 

How REM-Mover Works 

Understanding how REM-mover 
works requires an elementary 
knowledge of the way in which the 
Apple actually stores a BASIC pro- 
gram. Individual statements are not 
stored in the computer as they appear 
in a program listing; instead, each 
statement is coded into a form which 
is more usable from the standpoint of 
the BASIC interpreter. 

One of the more important aspects 
of this coding is the assignment of a 
"token" to each BASIC keyword. 
That is, every keyword is given a 
number, called a token, and it is this 
number, rather than a string repre- 
sentation of the keyword, which is 
used by the interpreter. Using tokens 
for keywords such as RUN and REM 
not only saves memory, but also 
speeds up the interpreting process. 
The coding process is referred to, ap- 
propriately enough, as "tokenizing." 

When you type in a program state- 
ment and press the return key, Ap- 
plesoft tokenizes the statement and 
inserts it into memory immediately 



following the statement with the next 
lowest statement number. Program 
storage for ROM Applesoft begins at 
the address 801 (hexadecimal). 

To illustrate the tokenizing process, 
consider the following useless (but in- 
structive) program: 

10 REM 
20 END 

The tokenized version of this pro- 
gram is 

801-07 08 0A 00 B2 00 OD 
808-08 14 00 80 00 00 00 

The bytes 801 through 806 are the 
machine representation of the first 
statement of the program, 10 REM. 
The first two bytes, 801 and 802, con- 
tain the starting address of the next 
statement: 807. (Note that the low 
byte precedes the high byte of the ad- 
dress.) The next two bytes, 803 and 

804, hold the statement number 00 
0A, or 10 in decimal. The fifth byte, 

805, contains the number B2, which 
is the token for the keyword REM. 
Finally, the sixth and last byte of the 
statement, 806, contains 00, which 
denotes the end of the statement. 

The next statement, 20 END, may 
be broken down into its constituent 
parts in exactly the same way. Notice, 
though, that the first two bytes of the 
second statement (807 and 808) seem 
to imply there is another statement 
which begins at 80D. This is clearly 
impossible, since the program con- 
sists of only two statements, not 
three. However, if you examine the 
first two bytes of this phantom state- 
ment, 80D and 80E, you will see that 
they both contain 00, instead of 
another set of next-statement point- 
ers. This is how Applesoft signifies 
the end of a program: whenever the 
next-statement pointer bytes contain 
zeroes, the interpreter stops. . .well, 
stops interpreting. 

Armed with the above information, 
you can now see how REM-mover 
works. Beginning at 801, REM-mover 
first tests this address and the next to 
see if they both contain zero; if they 
do, REM-mover stops. Should the ze- 
ro test fail, REM-mover then checks 
the fifth byte of the statement for the 
number B2, to see if the statement is a 
REM statement. If B2 is not found, 
REM-mover proceeds to the next 
statement, whose address is found in 
the first two bytes of the statement 
currently being examined. This pro- 
cedure continues until either a REM 
statement is found or the end of the 
program is reached. 

If REM-mover does encounter a 



REM statement, the next step it takes 
is to calculate an offset number, 
which is equal to the difference be- 
tween the address of the next state- 
ment and the address of the REM it- 
self. The offset is not used immedi- 
ately, but is stored temporarily in the 
zero page location 19. Next, REM- 
mover shifts down to the address of 
the REM all of the remaining bytes of 
the program statements which follow 



*300LLLLLL 



0300- 

Si8?= 

0309- 
0306- 
030D- 




0316- 
03 1C- 

83i§: 

0321- 
0323- 
0325- 
0327- 
0329- 
032B- 
032D- 
032F- 
0331- 
0334- 
0336- 
0337- 
0339- 
033A- 
>33B- 



0: 



0365- 
0367- 
0369- 
0366- 
036D- 
036F- 

§371- 
373- 
0374- 

§376- 
377- 
0378- 
037A- 
0376- 
037C- 
037D- 
837F- 
0381- 
0383- 
0385- 
0387- 
0388- 
0389- 
0386- 
838D- 
838F- 
0390- 
0392- 
0394- 
0395- 
0397- 
0398- 
039A- 
039D- 
039F- 
03A0- 
03A2- 
03A4- 
03A6- 
03A8- 
03AA- 
03A8- 

0363- 
0365- 
0367- 
8369- 
03BC- 



D8 

A9 01 
A0 08 
85 06 

84 07 
A2 00 
A8 00 
Bl 06 

85 08 
DO 01 
E8 

C8 

Bl 06 
85 89 
D0 01 
E6 
E0 02 

g| 01 



06 



06 



A4 09 
85 86 
84 87 
4C 7D 

00 



83 



>A 
>V 
STA 
STV 
LDX 
LDV 

STA 
BNE 
I NX 
INV 
LDA 
STA 
BNE 
I NX 
CPX 

1VI 

LDV 
LDA 

BEQ 
LDA 
LDV 
STA 
STV 

Imp 

LDA 
PHA 
LDA 
PHA 
SEC 
LDA 

m 

LDV 
LDA 
STA 
INC 
BNE 
INC 
INC 
BNE 
INC 
LDA 
CMP 
BNE 
LDA 
CMP 
BNE 
LDA 
STA 
STA 
STA 
STA 

b?g 

STA 
STA 

STA 
PLA 
STA 
TAV 
PLA 
STA 
PHA 
TVA 
PHA 
LDX 
LDV 
LDA 
STA 
BNE 
I NX 
INV 
LDA 
STA 
BNE 
I NX 
CPX 
BNE 
PLA 
STA 
PLA 
STA 
JMP 
LDV 
SEC 
LDA 
SBC 
STA 
STA 
BCS 
INV 
DEC 
LDA 
STA 
LDA 
LDV 
STA 
STV 
JMP 
BRK 



#♦01 
#♦08 
*06 
♦07 

#*00 
#♦00 

<*06> 

♦08 

*8314 



<*06>,V 
♦09 
♦03 1C 

#*02 
♦8321 

#♦04 

<*06>,V 

#♦82 

♦0334 

♦06 

♦89 

♦86 

♦07 

♦0309 

♦07 

♦06 



♦08 




(♦88:>,V 
< ^86 > , V 
♦06 
♦034D 

♦0? 

♦08 

♦0353 

♦09 

♦08 

♦AF 

♦0343 

♦60 

♦09 

♦0343 

♦06 

♦AF 

♦69 

♦66 

♦6D 

♦07 

♦60 

♦6A 

♦6C 

♦6E 

♦8e 



♦07 



#♦08 

#♦00 

(♦06>,V 

♦08 

♦8386 



(♦66>,V 

♦09 

♦0390 

#♦02 
♦039D 

♦06 

♦07 

♦8309 

#♦08 

♦06 

♦ 19 

♦88 

<*0&>»V 

♦03B1 

♦09 

♦09 

<#06>,V 

♦06 

♦09 

$i* 

♦037D 



Listing 1. REM-mover machine-language pro- 
gram. 



Microcomputing, December 1981 113 



the REM, thereby covering up the 
REM. 
After the shift operation, the BASIC 



program's length is decreased by an 
amount equal to the offset mentioned 
above. To compensate for this de- 



C START ^ 




-STATEMENT POINTER " 










INITIALIZE NSP 
ADDRESS TO $801 


NOTE "NSP" MEANS "NEXT 




1 ^_ 
















GET NEXT ADDRESS 




<^END 


^N. NO 


t 


^\ NO 


? s' 






J YES 


\ RE 




REPLACE NSP BY 
CONTENTS OF NSP 
AND NSP ♦ 1 


C RETURN J 


> yS 




"~ . 




1 YF ^ 












SAVE REM ADDRESS, 
CALCULATE "OFFSET- 












SHIFT BASIC 
PROGRAM 










ADJUST APPLESOFT 
POINTERS 










SET NSP ADDRESS 
TO ADDRESS OF 
"OLD" REM 













crease in program length, REM- 
mover subtracts the offset from sev- 
eral important Applesoft pointers, 
then stores the results back into the 
proper locations. These pointers are 



Fig. I. REM -mover flowchart. 



3CALL- 


-151 
















*30G. 3BC 
















0300" 


D8 


£9 


01 


A0 


08 


85 


06 


84 


0308- 


07 


£2 


00 


A0 


00 


Bl 


06 


85 


0310- 


08 


D0 


01 


E8 


C8 


Bl 


06 


85 


0318- 


09 


D0 


01 


E8 


EO 


02 


D0 


01 


0320- 


60 


A0 


04 


Bl 


06 


C9 


B2 


F0 


0328- 


0B 


AS 


08 


A4 


09 


85 


06 


84 


0330- 


07 


4C 


09 


03 


A5 


07 


48 


A5 


0338- 


06 


48 


38 


A5 


08 


E5 


06 


85 


0340- 


19 


R0 


00 


Bl 


08 


91 


06 


E6 


0348- 


06 


D0 


02 


E6 


07 


E6 


08 


D0 


0350- 


02 


E6 


09 


A5 


08 


C5 


AF 


D0 


0358- 


EA 


A5 


B0 


C5 


09 


D0 


E4 


A5 


0360- 


06 


85 


AF 


85 


69 


85 


6B 


85 


0368- 


6D 


A5 


07 


85 


B0 


85 


6A 


85 


0370- 


6C 


85 


6E 


68 


85 


06 


A8 


68 


0378- 


85 


07 


48 


98 


48 


A2 


00 


A0 


0380- 


00 


Bl 


06 


85 


08 


D0 


01 


E8 


0388- 


C8 


Bl 


06 


85 


09 


D0 


01 


E8 


0390- 


EO 


02 


D0 


89 


68 


35 


06 


63 


0398- 


85 


07 


4C 


09 


03 


A0 


00 


38 


03A0- 


A5 


08 


E5 


19 


85 


08 


91 


06 


03A8- 


B0 


07 


C8 


C6 


09 


A5 


09 


91 


03B0- 


06 


A5 


08 


A4 


09 


85 


06 


84 


03B8- 

* 


07 


4C 


7D 


03 


00 








Listing . 


2. REM- 


mover hex dump. 



the ultimate computer accessory 

Your own MICROCOMPUTER CHIP! 

T. M. 

An authentic microprocessor suspended in clear lucite. 




At^lUML ol£C 



COMPUTER MARKETING SERVICES, INC. 
300 West Marlton Pike ^331 

Cherry Hill, N.J. 08002 

Please send me: 
MICROCOMPUTER CHIP 



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□ CHECK D MASTERCARD G VISA 

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Signature 



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114 Microcomputing, December 1981 





















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contained in the addresses 69 
through 6E and in AF and BO. Rather 
than go into a detailed explanation of 
the functions of these pointers, let me 
refer you to the appendix in the Ap- 
plesoft II Reference Manual entitled 
"Zero Page Memory Map." 

Next, the same offset is used again 
to adjust the next-statement pointer 
bytes for all of the shifted statements. 
REM-mover returns to the address of 
the first byte of the now-removed 
REM statement; this address is now 
the address of the statement which 
originally followed the REM. The off- 
set is then subtracted from these two 
bytes and the result is deposited back 
into the addresses. Using this new 
pointer address, REM-mover goes to 
the next statement, subtracts the off- 
set and repeats this procedure until it 
reaches the end of the program. 

Finally, the REM-mover returns to 
the address of the removed REM 
statement and starts anew the search 
for the next REM. When all of the 
REM statements have been removed, 
the machine-language program re- 
turns control of the computer back to 
you. REM-mover is quite fast; it will 
delete 1000 bytes of REM statements 



in less than 18 seconds. 

Because the algorithm for remov- 
ing REMs can be confusing, I have in- 
cluded Fig. 1 and Table 1. Fig. 1 is a 



3LI 


ST 




10 


REM 


REM STATEMENTS 


20 


REM 




30 


REM 




40 


FOR 


I = 1 TO 1000 


50 


REM 




60 


REM 


AND IN LOOPS, 


70 


REM 




80 


REM 


CONSUME TIME! 


90 


REM 




100 


NEXT 



3 CALL 768 



DLIST 



40 FOR I = 1 TO 10G0 
100 NEXT 



simplified flowchart of the REM- 
mover program and Table 1 lists the 
addresses and functions of REM- 
mover' s important routines. ■ 



:list 



10 


REM 


■ ■ i 


. . REM STATEMENTS 


20 


REM 






30 


REM 






40 


FOR 


I i 


s 1 TO 1000 


50 


REM 






60 


REM 


• ■ i 


. -AND IN LOOPS, 


70 


REM 


■ • i 


. - REM STATEMENTS 


80 


REM 


m m i 


. -WASTE TIME! 


90 


REM 






100 


NEXT 




DCALL 768 




3LI:= 


5T 






40 


FOR 


I = 


= 1 TO 1000 


100 


NEXT 





Listing 3. REM statements can drastically increase program execution time. The program containing 
REM statements took 3.5 seconds to complete a RUN, while the version without REM statements re- 
quired only 1.2 seconds. 




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Microcomputing, December 1981 115 



This month, Microcomputing's 68xx expert reviews a "dynamite" program, 

and builds a 48K 6809 system. 



68xx Secrets 



By Peter A. Stark 



When asked to review Dynamite 
—a 6809 disassembler program 
—I jumped at the chance. The first 
step, of course, was to get my sys- 
tem to the point where switching 
back and forth between the 6800 and 
6809 processor boards would be 
easy. Little did I know what that 
would lead to! 

The review of Dynamite turned out 
to be the last thing done, but I'll cover 
that first. 

Dynamite is a superb disassembler 
program being marketed by the Com- 
puter Systems Center (13461 Olive 
Blvd., Chesterfield, MO 63017). Al- 
though it runs on a 6809 and requires 
the FLEX 9 disk operating system 
and a minimun of 24K bytes of pro- 
grammable random-access memory 
(RAM), it can disassemble both 6800 
and 6809 code. 

Using the word superb to describe 
it is not an exaggeration. In quite 
a bit of use, it has proven to be invalu- 
able and, despite much effort, I can 
think of little I'd change on it if I had 
my way. 

Essentially, a disassembler is a pro- 
gram which takes a machine-lan- 
guage program and translates it into 
assembly language. Several other 
68xx disassemblers are available, 
dating all the way back to the SWTP 
Desembler, and a Motorola disas- 
sembler before that. Dynamite is 
thus not the first, but it definitely has 
some features that put it in a class of 
its own. 

Unlike earlier disassemblers that 
work on a machine-language pro- 
gram in memory, Dynamite takes 
machine code from a disk file. This 

116 Microcomputing, December 1981 



has several advantages. It's not nec- 
essary to load the program first, and 
worry about whether it will conflict 
with the disassembler itself. A more 
visible advantage is that you don't 
have to even know the starting and 
ending addresses of the program be- 
ing disassembled. Even if it is split up 
into several segments which lie in dif- 
ferent places, Dynamite will insert 
the appropriate ORG statements into 
the assembly code, and will not disas- 
semble locations that are not part of 
the program. 

(It is possible to disassemble just 
part of a disk file. This is useful if you 
need to work on a certain segment of 
a program— I/O, for example, or 
when the program is too large for the 
assembly listing to fit on one disk.) 

Dynamite can produce a printed 
disassembled listing (which includes 
both the machine code as well as the 
assembly-language code in the same 
format as would be produced by an 
assembler), or it can write just the as- 
sembly-language code to another 
disk file. This code is in the right for- 
mat so it can immediately be reas- 
sembled. I tried it out on several long 
system programs, to see whether, if I 
disassembled with Dynamite and 
then reassembled its output, I would 
get the same machine-language pro- 
gram. In each case, that's exactly 
what I got. It's obviously not very 
useful, but it is a good test to make 
sure Dynamite works. 

The foregoing are simply the basics 
that any good disassembler should 
do. But Dynamite has some addition- 
al features. 

First, a typical machine-language 



program does not contain only in- 
structions. Buried among the instruc- 
tions may be ASCII text, data or ad- 
dress pointers. Since no disassembler 
can be intelligent enough to find 
these by itself, there must be some 
way of manually identifying and 
specifying them. 

If you have a printed program list- 
ing of what you're disassembling, 
then it's a simple (though perhaps 
lengthy) matter to go through it and 
identify each portion. Lacking that, 
Dynamite can help. By invoking an 
optional ASCII printout (in which 
Dynamite converts all printable 
codes into their ASCII characters and 
prints them), it is easy to find text 
strings in the code. Since Dynamite 
converts all unrecognizable instruc- 
tions into FCB statements automati- 
cally, this is a good beginning. By let- 
ting Dynamite go through the ma- 
chine-language program several 
times, displaying the result on the ter- 
minal, you can visually identify most 
data and text areas and separate them 
from pure code. 

Once program and data areas are 
identified, you must tell Dynamite 
what they are. This information can 
be entered directly from the key- 
board, or can be stored in a command 
file. Direct keyboard entry is more 
convenient and faster, but really only 
useful for short programs. When dis- 
assembling long programs, it is far 
more convenient to store this infor- 
mation as a separate command file, 
which is read by Dynamite during 

Address correspondence to Peter A. Stark, PO Box 
209, Mt. Kisco, NY 10549. 



disassembly. This latter approach 
is especially convenient when mak- 
ing multiple passes through a strange 
program. As each pass uncovers more 
data and text areas, you simply add 
them to the command file without re- 
typing information already there. 

Dynamite command files are text 
files that look like this: 

A 2010-2022 
B 2044-2046 
L 2100-2101 
W 2200-2213 

The letters identify the type of data— 
A for ASCII, B for byte, L for label 
and W for two-byte (word) data— and 
are followed by the address range. 
For example, the above example 
specifies that locations 2010 through 
2022 contain ASCII text. 

A typical calling sequence to start 
Dynamite looks like 

+ + + DYNAMITE INFILE OUTFILE 
+ OPTIONS + COMMAND-FILE 

which contains the disk file names of 
the machine-language code input file, 
as well as the assembly-language out- 
put file, if any, a list of options, and 
the name of the command text file. 

Possible options include printing of 
ASCII codes, prompting for com- 
mands from the keyboard, writing to 
the disk or a printer, generating line 
numbers or paginating, disassem- 
bling just a segment of a program, 
disassembling 6800 or 6809 code and 
using alternate disk drives. 

An even more interesting aspect of 
Dynamite is how it handles the gen- 
eration of labels. Whenever disas- 
sembling a machine-language pro- 
gram into assembly language, you 
must insert labels into the resulting 
assembly code. Dynamite does this 
by generating dummy labels which 
consist of the letter L followed by the 
address of that label in the original 
program; for example, LE1D1 would 
be the label assigned to location E ID 1 
hexadecimal. This makes it easy to 
find these labels in an assembly 
listing. 

But many locations already have 
standardized labels. For example, 
most 6800 users will recognize E1D1 
as being the address of OUTEEE in 
the monitor. Dynamite is smart 
enough to know that too! 

In addition to reading a command 
file from disk, Dynamite can also 
read label files. A label file is a file 
that tells Dynamite what labels to as- 
sign to specific locations. 

Dynamite is supplied with five la- 
bel files: DISLBL00, DISLBL09, 
SBUGLBL, SWTBGLBL and 



B 0050-0 1FF 


A 


027D-027E 


L 


02EA-02EB 


B 


034A-034A 


A 0214-021A 


L 


027F-0280 


A 


02EC-02F3 


A 


034B-0354 


L 021B-021C 


A 


0281-0287 


L 


02F4-02F5 


A 


044C-044D 


A 021D-021E 


L 


0288-0289 


A 


02F6-02F7 


A 


0458-045E 


L 021F-0220 


A 


028A-028B 


L 


02F8-02F9 


A 


0464-0470 


A 0221-0227 


L 


028C-028D 


A 


02FA-02FE 


A 


0476-0482 


L 0228-0229 


A 


028E-0291 


L 


02FF-0300 


A 


0946-0948 


A 022A-022B 


L 


0292-0293 


A 


0301-0304 


L 


0949-094A 


L 022C-022D 


A 


0294-0298 


L 


0305-0306 


A 


094B-094E 


A 022E-0234 


L 


0299-029A 


A 


0307-030B 


L 


094F-0950 


L 0235-0236 


A 


029B-029D 


L 


030C-030D 


B 


0951-0952 


A 0237-023B 


L 


029E-029F 


A 


030E-030F 


L 


0953-0954 


L 023C-023D 


A 


02A0-02A4 


L 


0310-0311 


B 


0955-0955 


A 023E-0240 


L 


02A5-02A6 


A 


0312-0315 


A 


0982-0988 


L 0241-0242 


A 


02A7-02AE 


L 


0316-0317 


A 


0A31-0A47 


A 0243-0244 


L 


02AF-02B0 


A 


0318-031B 


A 


0BF2-0C07 


L 0245-0246 


A 


02B1-02B3 


L 


031C-031D 


A 


0C77-0C86 


A 0247-024D 


L 


02B4-02B5 


A 


031E-031F 


A 


0D7F-0DCA 


L 024E-024F 


A 


02B6-02B7 


L 


0320-0321 


A 


0FCA-0FD3 


A 0250-0251 


L 


02B8-02B9 


A 


0322-0328 


A 


10B4-10CF 


L 0252-0253 


A 


02BA-02C1 


L 


0329-032A 


A 


1241-1244 


A 0254-025A 


L 


02C2-02C3 


A 


032B-032C 


L 


1245-1246 


L 025B-025C 


A 


02C4-02C5 


L 


032D-032E 


A 


1247-124B 


A 025D-0260 


L 


02C6-02C7 


A 


032F-0334 


L 


124C-124D 


L 0261-0262 


A 


02C8-02CD 


L 


0335-0336 


A 


124E-1251 


A 0263-0267 


L 


02CE-02CF 


A 


0337-0338 


L 


1252-1253 


L 0268-0269 


A 


02D0-02D1 


L 


0339-033A 


A 


1254-1258 


A 026A-026B 


L 


02D2-02D3 


A 


033B-033C 


L 


1259-125A 


L 026C-026D 


A 


02D4-02D8 


L 


033D-033E 


B 


125B-125B 


A 026E-0271 


L 


02D9-02DA 


A 


033F-0343 


A 


1511-1525 


L 0272-0273 


A 


02DB-02E3 


L 


0344-0345 


A 


17EF-1859 


A 0274-027A 


L 


02E4-02E5 


A 


0346-0347 


B 


185A-19DA 


L 027B-027C 


A 


02E6-02E9 


L 


0348-0349 






Listing 1. . 


Dynamite command file 


for disassembling the MiniFlex editor. 



MFLEXLBL. These contain, respec- 
tively, the labels for 6800 FLEX, 6809 
FLEX, SBUG, SWTBUG and 6800 
MiniFLEX. (FLEX, UNIFLEX and 
MiniFLEX are registered trademarks 
of Technical Systems Consultants, 
and SBUG and SWTBUG are regis- 
tered trademarks of Southwest Tech- 
nical Products Corp.) These label 
files are remarkably complete, and 
even include some data not common- 
ly known. 

Using these label files, Dynamite 
produces a very readable assembly 
listing. But there is more— it is easy to 
write your own label file, which can 
then either be appended to one of the 
predefined label files, or can be used 
in addition to it. Thus it is possible to 
produce an assembly-language file 
which is full of meaningful labels, 
and do it fairly simply. With other 
disassemblers, this can only be 
achieved by fairly lengthy editing of 
the resulting assembly code. 

My only complaint about Dyna- 
mite has to do with its label files. To 
make it easy for Dynamite to read the 
file, label files are written as assem- 
bly-language files and then assem- 
bled. For example, a typical label file 



might begin as 

FCC INEEE' 
FDB $E1AC 
FCC OUTEEE' 
FDB $E1D1 

and would then have to be assembled 
into a .BIN file before Dynamite can 
use it. It would be nice if Dynamite 
could use the text file as is without 
the extra assembly. But that is just a 
minor inconvenience. Other than 
that, Dynamite is superb. 

Dynamite Example 

Because Dynamite can disassem- 
ble 6800 as well as 6809 code, it 
seemed useful to try it out on a real 
practical job— converting the Mini- 
FLEX version of TSCs text editor to 
run under FLEX 9 on a 6809. The 
decision to convert a MiniFLEX edi- 
tor to FLEX 9, rather than starting 
with a FLEX 2 editor, was made since 
it seemed to be more of a test of 
Dynamite. It worked out well, but in 
the process I discovered that it really 
wasn't so easy and practical after all. 
Though Dynamite did a great job dis- 
assembling the editor, an editor was 
needed to edit the resulting assembly 
code before it could be reassembled 

Microcomputing, December 1981 117 



for the 6809. And if you already have 
a 6809 editor, then there isn't much 
need to convert one from the 6800. 

Nevertheless, the procedure for do- 
ing a typical conversion goes like this: 

Since Dynamite runs on a 6809, the 
first step is to get the program to be 
converted onto a disk that Dynamite 
can read on the 6809. There are sev- 
eral ways to do this. One is to load it 
into memory on a 6800 system, dump 
it out to cassette, read that cassette in- 
to a 6809 system and save it on tape. 
If the 6800 and 6809 systems are near 
each other, their RS-232C ports can be 
connected, and the cassette com- 
mands used to transfer from one to 
the other. A third way is to transfer 
the program from a MiniFLEX disk 
to a FLEX 2 disk on the 6800, result- 
ing in a disk that can be read on the 
6809. Finally, it is possible to write a 
utility for reading MiniFLEX disks on 

a 6809. 

Once the program is on a 6809 disk, 
it is time to do a few disassemblies 
and identify data areas. Listing 1 is 
the resulting command table I came 
up with for the MiniFLEX editor. 
Normally, an editor would be used to 
prepare this file, though it is possible 



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to use the BUILD utility if you type 
well enough. 

The next step is to use Dynamite to 
disassemble the code, resulting in an 
assembly-language file on a 6809 
FLEX 9 disk. This file must now be 
edited so it can be reassembled into 
the correct code. 

When converting the editor itself, 
this turns out to be a problem that has 
both obvious and not-so-obvious 
solutions. (A year ago, when I pre- 
dicted that converting to a 6809 
would cost a lot of money for soft- 
ware, one irate reader complained 
about my negative attitude, and in- 
sisted that he had no problem con- 
verting all of his disk software from a 
6800 to a 6809. Wonder how he 
solved this one!) 

The editing involved several items. 
First, all DOS references had to be 
changed to their new addresses. (See 
Listing 2 for a cross-reference list of 



commonly-used locations in various 
DOS implementations.) 

For the benefit of anyone trying to 
repeat this particular conversion, 
several references to the 6800 moni- 
tor also had to be changed. This in- 
volved changing an A048 hexadeci- 
mal to CC16, E1D1 to CDOF, and 
El AC to CD09. Another change in- 
volved changing a BEQ instruction to 
LBEQ (in line 2682 if you use the 
same command file). Since the 6809 
code is slightly longer, the branch in 
the 6809 code was too long for the 
standard BEQ instruction. Another 
change involved changing a line 
which read CPX #LINBUF to read 
CPX #$C000, so as to avoid potential 
problems with the machine stack. 

The last change required lengthen- 
ing the read and write FCB buffers 
from the 192 bytes used in MiniFLEX 
to the 320 bytes used in FLEX 9. In 
my case, the obvious places were to 



LINBUF 


7000 


A080 


C080 


PRTDVC 




AC39 


CC39 


TTYBS 


7080 


AC00 


ccoo 


PINIT 




ACC0 


ccco 


TTYDEL 


7081 


AC01 


CC01 


PCHK 




ACD8 


CCD8 


TTYE0L 


7082 


AC02 


CC02 


POUT 




ACE4 


CCE4 


TTYDP 


7083 


AC03 


CC03 


COLDS 


7100 


AD00 


CDOO 


TTYWD 


7084 


AC04 


CC04 


WARMS 


7103 


AD03 


CD03 


TTYNL 


7085 


AC05 


CC05 


RENTER 


7106 


AD06 


CD06 


TTYTB 


7086 


AC06 


CC06 


INCH 


7109 


AD09 


CD09 


TTYBE 




AC07 


CC07 


INCH2 




ADOC 


CD0C 


TTYEJ 


7088 


AC08 


CC08 


0UTCH 


710C 


ADOF 


CDOF 


TTYPS 


7089 


AC09 


CC09 


0UTCH2 


7136 


AD12 


CD12 


TTYESC 


708A 


AC0A 


CC0A 


GETCHR 


710F 


AD15 


CD15 


SYSDRV 


708B 


AC0B 


CC0B 


PUTCHR 


7112 


AD18 


CD1& 


WRKDRV 


708C 


AC0C 


ccoc 


INBUFF 


7115 


AD1B 


CD1B 


SYSMTH 




AC0E 


CC0E 


PSTRNG 


7118 


AD1E 


CD1E 


SYSDAY 




AC0F 


CC0F 


CLASS 


711B 


AD21 


CD21 


SYSYR 




AC10 


CC10 


PCRLF 


711E 


AD24 


CD24 


LSTTRM 


7091 


AC11 


CC11 


NXTCH 


7121 


AD27 


CD27 


UCMDTB 


7092 


AC12 


CC12 


RSTRI0 


7124 


AD2A 


CD2A 


LINPTR 


7094 


AC14 


CC14 


GETFIL 


7127 


AD2D 


CD2D 


ESCRET 


7096 


AC16 


CC16 


LOAD 


712A 


AD30 


CD30 


CURCHR 




AC18 


CC18 


SETEXT 


712D 


AD33 


CD33 


PRVCHR 


709A 


AC19 


CC19 


ADDBX 


7130 


AD36 


CD36 


CURLIN 


709B 


AC1A 


CC1A 


0UTDEC 


7133 


AD39 


CD39 


LDR0FF 


709C 


AC1B 


CC1B 


0UTHEX 


7139 


AD3C 


CD3C 


XFERFG 


709E 


AC1D 


CC1D 


RPTERR 


713C 


AD3F 


CD3F 


XFERAD 


709F 


AC1E 


CC1E 


GETHEX 


71 3F 


AD42 


CD42 


ERRTYP 


70A2 


AC20 


CC20 


0UTADR 




AD45 


CD45 


SPECI0 




AC21 


CC21 


INDEC 




AD48 


CD48 


0UTSW 


70A3 


AC22 


CC22 


D0CMND 


7142 


AD4B 


CD4B 


INSW 




AC23 


CC23 


STAT 




AD4E 


CD4E 


0UTFIL 




AC2U 


CC24 


SYSFCB 


7740 


A840 


C840 


INFIL 




AC26 


CC26 


FMSINT 


7800 


B400 


D400 


CMDFLG 


70A5 


AC28 


CC28 


FMSCLS 


7803 


B403 


D403 


CURCLM 


70A6 


AC29 


CC29 


FMS 


7806 


B406 


D406 


MEMEND 




AC2B 


CC2B 


BASFCB 


7809 


B409 


D409 


ERRVEC 




AC2D 


CC2D 


CURFCB 


780B 


B40B 


D40B 


FILEK0 




AC2F 


CC2F 


VRFYFG 


782D 


B435 


D435 


CPUTYP 




AC33 


CC33 


TTYDPX 


7087 






PRTADR 




AC35 


CC35 


ACIAFG 


70A1 






PRTLNG 




AC37 


CC37 











Listing 2. DOS addresses for MiniFlex, Flex 2.0 and Flex 9. 



118 Microcomputing, December 1981 



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add an RMB 128 just before labels 
L191A and again just before the $0D 
that is just above L19DB. A not so ob- 
vious change (which took a while to 
find) was to change a ST A 192,X in- 
struction to ST A 320, X in the middle 
of the program. 

And then it worked! 

Disassembling an editor and then 
converting it to run on the 6809 is not 
really practical, but is at least feasi- 
ble. But other jobs are not so feasible. 
For example, it would be very diffi- 
cult to convert the 6800 assembler to 
run on the 6809 and produce 6809 
code. Likewise, converting 6800 
FLEX into 6809 FLEX, or converting 
TSC 6800 BASIC to the 6809 would 
be well-nigh impossible. 

In other words, Dynamite is not the 
solution to the high software cost of 
upgrading from a 6800 to a 6809. But 
it is a good starting point, especially 
these days when so few software ven- 
dors provide the source code for their 
products. 

Connector Problems Lead to a 
Separate 6809 System 

Though it is possible to plug both 
the 6800 and the 6809 microproces- 
sor boards into the system at the 
same time and switch them in and 
out by adding some logic circuitry, I 
decided to switch back and forth be- 
tween the two processors by plugging 
and unplugging the boards. Every- 
thing worked just fine for a while, but 
soon I found my system becoming 
very unreliable. Sometimes it would 
work with one board and not the 
other; other times it wouldn't work 
with either. 

After many hours of troubleshoot- 
ing—and some lost data and pro- 
grams—I narrowed it down to a con- 
nector problem. There was quite a bit 
of corrosion on the motherboard con- 
nectors and the system board connec- 
tors. With the continued plugging 
and unplugging of boards, this corro- 
sion was being loosened, and was 
finding its way between contacts. I 

had been warned about this problem 
by Harold Mauch, the president of 
Percom Data Company, over two 
years ago, but never really expected 
to get it. What to do? 

Mauch' s solution was to clean the 
contacts with a Pink Pearl eraser at 
periodic intervals. While this 
worked, others suggested that per- 
haps isopropyl alcohol on a piece of 
cloth was safer. I ultimately went to 
the alcohol, with a cloth used on the 
male contacts of the motherboard, 



and a pipe cleaner used on the female 
contacts of the plug-in boards. I have 
also tried a freon aerosol spray; while 
this seems to work just as well, it is 
much more expensive. (I spoke with 
the representatives of the connector 
manufacturer at a recent trade show, 
but they weren't able to offer any 
suggestions.) 

Some manufacturers try to avoid 
the problem by using gold-plated 
connectors rather than the tin-plate 
used by SWTP. While this is un- 
doubtedly the better way, it is expen- 
sive (the additional cost of gold con- 
nectors over tin adds at least $100 to 
$200 to the cost of an entire system). 
Moreover, if boards will be plugged 
and unplugged often, then the very 
thin gold coating is likely to be worn 
off quite quickly. It is also not a good 
idea to mix the two kinds of connec- 
tors—having gold-plated cards 
plugged into tin-plated connectors on 
the motherboard, for instance. 

SWTP has recently been shipping 
their systems with a lubricant on the 
connector pins. I have not been able 
to find out what that is, but am on the 
trail of another solution. 

Connector corrosion is obviously a 
problem not just in SS-50 systems. 
For example, Motorola has run into 
that problem on their commercial 
two-way radios, and has just intro- 
duced a service kit consisting of a 
contact cleaner and lubricant for 
cleaning their tin-plated connectors. I 
have one on order, and will try it out. 
(Readers in the two-way radio busi- 
ness may want to read Motorola Ser- 
vice and Repair Note 908; their part 
numbers are 11-82346D01 for the 
freon cleaner and 11-80344A80 for 
the lubricant. 

The problem with all of these solu- 
tions, of course, is that trying the 
wrong chemical may make the prob- 
lem much worse. 

Since connector problems are 
greatly worsened by plugging and 
unplugging boards, I decided that 
this had to be avoided. While I could 
have set up a switching scheme so 
both boards could stay plugged in to- 
gether, this conflicted with some 
other plans, and so I decided to sim- 
ply put some of my extra boards to 
use by building a separate 6809 
system. 

Rack-Mounting an S-50 System 

While a simple system can easily 
occupy the top of a table or work- 
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take up a lot of room. I therefore de- 



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Microcomputing, December 1981 121 




mmm 



Photo 1. SWTP motherboard and a slightly modified power supply fit inside the drawer I chose with room 
to spare. 



cided to mount my system in a rack. 
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or other system components. Front 



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panels are mostly 19 inches wide, 
and hence the rack is often called a 
19-inch rack. 

As shown in Photos 1 and 2, the 
system is mounted in a pull-out 
drawer (from Premier Metal Prod- 
ucts Company, 381 Canal Place, 
Bronx, NY 10451), which measures 
16 by 16 inches, and is a perfect fit for 
my SWTP motherboard and power 
supply. I used lOVi-inch-high 
drawers (model TDR- 1014) for each 
system, and a seven-inch-high 
drawer (model TDR-719) for an extra 
power supply. 

Accessories such as disk drives are 
mounted on slide-out shelves (model 
TWS-319). The drawers and shelves 
are mounted on metal slides and can 
be slid completely out the front of the 
rack, so it is easy to work on any part 
of the system. The only problem has 
been with an occasional wire getting 
stuck in the back as a drawer or shelf 
is pulled out. 

I keep the front of the drawer open 
slightly to allow heat to escape, but a 
fan may eventually be needed. 

Heat Dissipation of 
Static Memory Boards 

Since I needed memory for my 
6809 system, I purchased the new 
32K byte static-memory board kit 
from Digital Research Computers of 
Texas (PO Box 401565, Garland, TX 
75040). Although this board is avail- 
able in kit form or wired, I chose the 
board plus support integrated circuits 
(ICs) plus sockets approach; at $90.95 
for a complete kit which includes 
everything except the memory chips 
themselves, this is an excellent buy. 

The board uses 64 type 21 14L RAM 
ICs; Digital Research specifies that 
these must be low power, and here is 
where I ran into some difficulties. I 
soon discovered that not all low-pow- 
er ICs are the same. 

I bought 64 ICs at $2.98 each from 
Active Electronics. The total power 
drain for the board with 32K of RAM 
installed is about 2.8 amperes, and 
the board runs quite warm. Although 
it is perfectly suitable for a cabinet 
with an open top, such as my original 
SWTP box, it is too warm for my un- 
ventilated rack. 

I subsequently discovered that 
even lower-power 21 14 ICs are avail- 
able. For example, Gimix uses Japa- 
nese 2114L RAM memories in their 
32K static board, and that board takes 
under 2 amperes as opposed to my 
2.8 amperes. This makes a big differ- 
ence on a board where the memory 



122 Microcomputing, December 1981 



chips are so close to each other as to 
almost touch. (With Gimix now sell- 
ing their ICs at a very attractive price, 
this would have been a very good 
combination.) 

The Digital Research board itself is 
of excellent quality, with silk-screen- 
ing and extended addressing options. 
Given the right low power ICs, it is 
an excellent way of providing 
economical static memory for a sys- 
tem. In my case, though, I did not 
have sufficiently low power ICs for 
my closed, unventilated cabinet. 

Rather than switch all 64 ICs, I 
switched to a different memory 
board— the 64K byte dynamic RAM 
board from Boaz Co. (Box 18081, San 
Jose, CA 95158). Though this board is 
somewhat more expensive (ranging 
from $80 for a bare board to $250 for 
an assembled board without the dy- 
namic RAM ICs), the memory chips 
themselves are cheaper. This board 
uses the same 4116 (16K by 1 bit) 
chips as used in the TRS-80, Apple 
and many other systems. Current 
prices of 16K upgrades for these com- 
puters are as low as $17, with the re- 
sult that even 64K of RAM chips cost 
under $70. 



This board has solved my prob- 
lems. Even with 64K of RAM in- 
stalled (though not all is switched in 
due to address conflicts with the 
monitor and I/O) the board runs 
much cooler than any static memory, 
with the possible exception of the 
new static RAMs such as are avail- 
able for Gimix. 

SWTP MP-09 CPU 
Board Modifications 

The next step was to modify my 
HUMBUG monitor to allow it to run 
on the 6809, so that I could have all 
the functions I had on my 6800. More 
problems. 

My 6809 HUMBUG occupies two 
2716 (erasable-programmable read- 
only memory) (EPROM) chips and 
has some very useful debugging and 
troubleshooting commands. Unfortu- 
nately, it didn't always work. It 
worked in one processor board, but 
not in another. Neither board worked 
in a different system. And some 
2716s worked, others did not. Not 
knowing whether the problem was 
with my hardware or software, I ob- 
viously suspected the software. But 
that did not seem to lead anywhere, 




Photo 2. Mounting the 6809 system in a stan- 
dard 19-inch rack provides a compact and neat 
installation. 



so I eventually transferred SWTP's 
SBUG monitor into a 2716, and that 
also didn't work. 
I eventually decided that the SWTP 



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Microcomputing, December 1981 123 



MP-09A CPU board just did not like 
2716 EPROMs. A conversation with 
the folks at Gimix (who have a re- 
markable knowledge of not just their 
own, but also their competitors', 
hardware) confirmed that I was right. 

Most 2716s are specified as having 
an access time of 450 nanoseconds 
(ns). This means that the 2716 must 
receive its address and chip select 
inputs at least 450 ns before its data 
output is needed, because that's how 
long it takes to access a specific 
location. 

In the MP-09A board, one memory 
cycle is 1000 ns long. The address is 
supplied to the 2716 at the beginning 
of the cycle, and the data is needed at 
the end of the cycle. Hence the ad- 
dress is supplied in time. But the chip 
select (which is a low pulse applied to 
pin 18 of the 2716) is not applied until 
about halfway through the cycle, 
leaving the 2716 about 400 to 500 ns 
to finish its job. This is just barely 
enough time, as most commonly 
available 2716 EPROMs are specified 
for an access time of 450 ns. Such a 
2716 will occasionally output the 
wrong data. (Now I finally under- 
stood the comment in the SBUG 



manual that when SBUG was burned 
into a 2716, the system could not run 
faster than a 1 MHz clock speed.) 

There are several solutions, such as 
slowing down the system clock, 
lengthening clock pulses during 
ROM accesses and so on. An obvious 
answer is to use a faster 2716 
EPROM. The 2716 is available in 
450, 350 and 250 ns access times. The 
350 ns part works in almost all cases, 
though the 250 ns part may have a 
somewhat greater safety factor. The 
disadvantage is that these faster 
EPROMs are more expensive, and 
difficult to get. I called a dozen sup- 
pliers who advertise 2716s in the 
popular magazines, and not one had 
anything faster than 450 ns. 

The correct, though not necessarily 
simplest, solution is to fix the 2716 
timing problem. This involves cut- 
ting the printed circuit board trace 
which leads to pin 18 of each 2716 
socket, and grounding pin 18 to keep 
the 2716 selected at all times; this 
works since t he s ame select signal 
also goes to the OE pin (pin 20) of the 
2716, and this pin takes over the 
selection job; it does not have the 
same delay as pin 18 does. 



Unfortunately, the trace which 
needs cutting is under the 2716 
socket. In my case, the sockets were 
open in the center and so a thin knife 
reached the trace; in some cases it 
may be better to bend pin 18 so it 
does not go into its socket, and 
ground it through a separate jumper. 

MP-R Programmer Notes 

The MP-R programmer is normally 
supplied with a cassette that contains 
6800 software. New EPROM pro- 
grammers are supplied with SWTP 
Application Notice AN- 109, which 
mentions that READPROM and 
WRITPROM utilities, which read 
and program 2716 EPROMs under 
FLEX 9, are available, along with 
FLEX 9, from SWTP for $10. 

READPROM and WRITPROM es- 
sentially transfer data from disk to 
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nearly as versatile as the original 
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124 Microcomputing, December 1981 













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NEC 12" MONITOR $ 189 

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NEC PC 8023 Printer 

100 CPS Tractor & Friction $ 639 

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APPLE II PLUS 48K $1139 

APPLE DISK w/3.3 DOS Controller $ 525 

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Interfaces: 

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x'See List of Advertisers on page 210 



Microcomputing, December 1981 125 



6809 FLEX Versions 

Although FLEX is a product of 
Technical Systems Consultants, sev- 
eral hardware manufacturers have 
licenses to modify it for their systems 
and sell the modified versions. 

Although the terms of the license 
agreements specify that the modifica- 
tions must be such that the modified 
systems must still be able to read and 
write standard unmodified disks and 
run standard software (such as TSC 
BASIC), the modified versions of 
FLEX will generally only run on the 
equipment they are designed for. 

The two biggest FLEX licensees 
are probably SWTP and Gimix. 
SWTP modifications to FLEX con- 
centrate mainly on making it com- 
patible with all the various SWTP 
6809 mainframes. 

At present three different SWTP 
6809 system configurations are 
supported: 

The /09 system is generally a 6800 
system with an MP-B or MP-B2 
motherboard, which has been con- 
verted by the installation of an MP-09 
board. Since this configuration uses 
the 6800-style motherboard (with 
modifications to move I/O from ad- 
dress 8000 (hexadecimal) to E000), 
I/O ports use four addresses per slot. 
Older, 6800-style I/O boards are used 
including the MP-S and MP-LA 
boards. This system does not use ex- 
tended addressing, and is therefore 
limited to a maximum of 56K bytes 
of RAM. 

The 69A and 69K systems are the 
assembled and kit versions, respec- 
tively, and use the newer MP-B3 
motherboard. These systems are also 
limited to 56K of RAM, but use the 
newer I/O bus structure which de- 
votes 16 addresses per I/O slot in- 
stead of four used on 6800 systems. 
For example, port 7 in the /09 system 
is at address E01C (hexadecimal), 
whereas in the 69K or 69A it is at ad- 
dress E070. This requires that the 
newer MP-S2 and MP-L2 interface 
boards be used. (Older I/O boards 
can be used with the new addressing 
modes, but not vice versa, since the 
new boards do not fit into the older 
mainframes.) 

Finally, the S/09 system uses the 
even newer MP-MB motherboard. 
I/O ports again use 16 addresses per 
slot and require the newer I/O 
boards; in addition, this motherboard 
allows extended RAM addressing, so 
that a total of 384K bytes of memory 
can be used (consisting of three 128K 

126 Microcomputing, December 1981 



RAM boards). Since the extended ad- 
dress lines are placed on the bus pins 
formerly used by the data rate lines, 
data rate signals must be generated 
separately. This system therefore has 
an additional plug-in board called the 
MP-ID, which contains the data rate 
generator as well as a parallel output 
port and interrupt timer. This board 



is located at address E080. 

SWTP versions of FLEX include ex- 
tra code (which is only run when the 
system is first booted) to test the sys- 
tem and set appropriate flags to indi- 
cate which system is being used. 
They also check the extent of memo- 
ry (including testing for extended 
memory) and configure the dynamic 



How Readable Is this Article? 

The June 1981 issue of Kilobaud 
Microcomputing had an interesting 
program, written by Richard R. 
Parry, for analyzing written text. 
The idea is to grade an article or 
other text to see how well it is writ- 
ten, and how well it might be un- 
derstood by the typical reader. 

A similar program (though writ- 
ten in assembly language and 
therefore much faster, as well as 
more complete) is available from 
the Frank Hogg Laboratory (130 
Midtown Plaza, Syracuse, NY 
13210). Written by Dale Puckett, 
the READTEST program is a very 
useful addition for anyone who 
does a lot of writing. (Dale Puckett 
also wrote the ESTHER program 
available from the Hogg Labora- 
tory. ESTHER is similar to the 
well-known ELIZA program, but 



much better thanithe usual micro- 
computer implementations) . 

READTEST reads a text file 
from disk, and analyzes it for con- 
tent. It counts the number of 
words and sentences, as well as 
the types of words. After comput- 
ing the average sentence length 
and other facts about the text, 
READTEST then prints out a short 
critique of how well it is written. 

(Hm ... if I were an English 
teacher, could I have my students 
type their papers into the comput- 
er, and then have the computer do 
the grading? Cute idea . . . ) 

To see how well this article 
stacks up (in its original form, be- 
fore the editors fix all my mis- 
takes), I ran READTEST on it. List- 
ing 3 shows the program's output, 
which I'm including here without 
editing. . .and without comment. 



1 



Number of linos ■ 7*8 
Number of words ■ 6628 
Number of sentenoes « 377 
Nuabor of proper nouns • 158 

Now counting personal words and affixes • • • 

Nuabor of personal words a 133 
Nuabor of affixes a 283* 
Aversge sentenoe length ■ 17 

Based on the average sentenoe length your r sting is: 
AVERAGE 

Based on the nuabor of affiles your rstlng is: VERT EAST 

Based on the nuabor of personal words, your r sting is: INTERESTING; similar 
to aatorlal found in the digests. 

Tour ovorsll readability index is: 118 

This means your story is • • • EAST 

READING. A fifth grader can understand it. Eighty-six percent of the 

population ean handle it. It is similar to material found in paperback 

fiction. 

Hopefully, you %r% pleased with your rstlng. If not, why not rewrite the 
story in so effort to communicate more effectively. Think short words, 
short sontenoes, snd short psrsgrsphs. Do not bo discouraged. Writing 
for any praotlosl purpose is s dlffloult snd elluslve srt. Remember, 
Ernest Heaalngwsy often spent eight hours writing four or five hundred 
words. 

GOOD LUCK 

Listing 3. 



and come out a winner 



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whether it's an interface 
problem or advice on the 
right peripheral for a home- 
brew system, use the free 
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address translator (DAT) on the pro- 
cessor board. These FLEX versions 
are currently supplied by SWTP only 
for newer disk controllers, and hence 
the required modifications to make 
them work with older disk control- 
lers are described in several of the 
Application Notices. 

Gimix versions of FLEX are also 
customized to fit their hardware. 
Gimix currently has three different 
disk controllers available, and so 
Gimix supplies three different ver- 
sions of 6809 FLEX rather than trying 
to have one version support all 
controllers. 

The 5/8 disk controller can be used 
with either 5-inch or 8-inch drives on 
6809 systems, and with 5-inch drives 
on 6800 systems. On 6809 systems it 
can be used with two-sided drives as 
well as double-track drives (which 
provide 80 tracks per side), but only 
in single density. This is the simplest 
of Gimix' s three controllers, but un- 
like some of the equivalent control- 
lers of other manufacturers, this one 
has a data separator and somewhat 
better design. As a result it is far more 
reliable and does not require periodic 
disk re-reads. 



The double-density programmed 
I/O (PIO) controller works only with 
five-inch drives on 6809 systems but 
allows double-density and/or double- 
sided and/or double-track operation. 
On a standard drive such as a Shugart 
SA-400, this controller provides 612 
256-byte sectors for a total storage of 
152K bytes in double density. Using 
an MPI model 92 drive, on the other 
hand, adds double-sided operation 
plus the capability to use 80 tracks on 
each side. This provides 2844 sectors 
of 256 bytes each, for a total of 71 IK 
per disk. 

Finally, the DMA disk controller 
allows all of the above options, and 
uses direct memory access (DMA) 
data transfer instead of programmed 
I/O. The major advantage of DMA 
controllers is that they allow double- 
density operation on eight-inch 
drives without requiring that the 
CPU clock speed be raised to almost 
2 MHz. Theoretically, this controller 
can be used on both 6800 and 6809 
systems; practically, though, only the 
6809 is supported by Gimix. 

For my separate 6809 system I 
chose the double-density PIO con- 
troller along with a pair of MPI 92 



disk drives. (It is staggering to realize 
that the resulting 1422K bytes of disk 
storage is more than that of the IBM 
1130 computer I have used at work 
for the last ten years.) Though this 
controller and drive combination is 
more expensive than those used on 
my 6800 system, I made the choice 
simply because here, at last, was 
something the 6809 could do that my 
6800 system could not. 

Although these drives use both 
sides of each disk, I use standard 
single-sided disks (like the Verbatim 
MD-525-01) with no difficulty. In 
fact, I have no trouble using some 
disks that have been discarded by a 
TRS-80 user because they gave him 
too many errors. The Gimix control- 
ler is really very reliable even on 
such unusable disks. 

The Gimix version of FLEX in- 
cludes a number of extra utilities 
that are supplied by Gimix for their 
systems, such as commands to set 
and read the clock chip which is 
available on Gimix boards, or pro- 
vide data to the arithmetic chip 
which is also on some processor 
boards. But it is the FLEX extensions 
that are most interesting. 



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128 Microcomputing, December 1981 



Instead of a NEWDISK utility, 
Gimix supplies a FORMAT program 
to format a blank disk. It prompts for 
a number of options, including sin- 
gle- or double-density operation, sin- 
gle or double sides, and the number 
of tracks to be formatted. This latter 
option is especially handy if you just 
need a few tracks for a temporary 
file, since formatting can take a long 
time for an 80-track, double-sided 
disk. 

Another useful utility called SET- 
UP is used to modify various drive 
parameters. As supplied, FLEX as- 
sumes that slow drives (having slow 
track-to-track movement) are used, 
but the SETUP utility can be used to 
change the speed at which FLEX 
moves the head to match the drive 



used. This is particularly handy 
when several different drives are 
used, some slow and some fast. An- 
other function is to tell FLEX how 
many drives are actually on the sys- 
tem, so that the system does not hang 
up if a nonexistent drive is specified 
in a command. 

80-track drives are normally in- 
compatible with 40-track drives, but 
Gimix FLEX can be configured to 
skip alternate tracks so that an 
80-track drive can read or write a 
40-track disk. This makes it possi- 
ble to interchange disks with systems 
using other types of drives and 
controllers. 

There is only one disadvantage I 
can think of in having so much disk 
storage (aside from the fact that one 



gets very sloppy when there is so 
much empty room). Since it is possi- 
ble to put hundreds of files on one 
disk, the directory grows large too. 
On FLEX, the directory starts on 
track 0, and so directory accesses are 
fast when the directory is small. But 
once there are more than a few dozen 
entries, the directory is continued on 
inner tracks, with the result that each 
directory read or write— of which 
there are many in normal operation- 
involves extensive head movement. 
This can slow down operation 
quite a bit. Fortunately, Gimix sup- 
plies an EXTEND utility to extend 
the directory size. When used on a 
new, freshly-formatted disk, EX- 
TEND adds up to ten more sectors to 
the directory. Since these new sectors 






SWTP Application Notices 



The 6809 system takes just a few 
paragraphs to describe, but in 
reaJiry it took months of ex- 
perimenting to figure it out. And 
then I discovered that SWTP had 
issued some Application Notices 
describing this fix, as well as other 
fixes, and that I could have saved 
myself all this work if I had known 
about them. 

Since I have discovered many 
other SWTP owners who do not 
know about these notes, here is a 
listing of what is available at the 
time of writing, though more Ap- 
plication Notices will probably ex- 
ist by the time this appears in 
print. As I have been unable to get 
an index or the notes themselves 
from SWTP, I suspect that you will 
have to contact your local SWTP 
dealer for a copy. 

Many of the changes or sugges- 
tions have been included with 
systems shipped after the date of 
the note, so even if a note applies 
to your equipment, it may not be 
necessary to get it unless the prob- 
lem exits. 

AN-101 (11-15-79). S/09 memory 
tests booting DMAF disks and 
system jumpers. 

AN- 102 11-21-79). Using the 
DMF-2 controller on 6800 sys- 
tems, or with Calcomp 143 drives. 

AN-103B (10-31-80). Notes on 
using the CDS-1 hard disk. 

AN-104 (12-13-79). Modifying 
the MP-09 CPU board into an MP- 



09 A board. If your CPU board 
works, then it has already been 
modified. 

AN-105 (12-13-79). Notes on us- 
ing the MP-09 or MP-09A CPU 
board in 6800 or /09 mainframes. 
AN- 106 (12-14-79). Using the 
DC-2 disk controller on MP-B3 or 
MP-MB motherboards. 

AN-107 (1-2-80). Differences be- 
tween SWTP 6809 systems, and 
patches to FLEX 9 versions 2.4 and 
2.5. 

AN-108 (1-8-80). Modifying the 
MP-S serial I/O board for printer 
handshaking. 

AN-109 (1-8-80). 6809 software 
notes for the MP-R programmer. 

AN-110A (2-14-80). How to use 
the Centronics 704 printer with 
SWTP computers. 

AN-111 (1-23-80). More patches 
to FLEX versions 2.4 and 2.5 and 
notes on maximum file size. 

AN-112 (1-25-80). Using serial 
printers with Multi User BASIC. 

AN-113 (2-26-80). Using FLEX 
version 2.6 with the MP-B3 
motherboard. 

AN-114A (9-8-80). DMF2 con- 
troller address decoding, and 
operation with UNIFLEX. 

AN-115 (4-25-80). Adjustments 
for Zenith monitors in some 
CT-82s. 

AN-116A (7-2-80). Using the 
SWTP Editor with printer spool- 
ing, etc. 

AN-117 (5-7-80). Modifying the 
6800 MP-A CPU board for use 
with the DMF2 disk controller. 
AN-118 (5-19-80). Notes on us- 



ing the MP-S2 serial interface. 

AN-119 (5-23-80). Testing 128K 
RAM boards with SBUG. 

AN-120 (7-16-81). Unpacking 
and packing QUME eight-inch 
drives. 

AN-121 (7-24-81). Notes on the 
CDS-1 hard disk. 

AN-122A (11-14-80). Updating 
S/09 systems to work with FLEX 
or UNIFLEX. Updates MP-09 
CPU board to revision C, MP-MP 
motherboard to revision A, and 
MP-ID board to revision C. 

AN-123 (10-16-80). Patches to 
FLEX version 2.6 for Shugart 
drives. 

AN-124 (10-21-80). Operating 
the S/09 at 2 MHz. 

AN-125A (1-8-81). Using FLEX 
version 2.7 with the DC-2, DC-3 
and DMF1 controllers, and Shu- 
gart or Calcomp drives. 

AN-126 (11-6-80). Using the 
Centronics 737-1 printer. 

AN- 127 (12-10-80). Modifying 
the MP-09 and MP-09 CPU boards. 

AN- 128 (12-11-80). Modifying 
the CDS-1 power supply. 

AN-129 (1-23-81). Modifying 
128K RAM boards for 2 MHz 
operation. 

AN-130 (2-17-81). Modifying 
69/A and 69/K computers for 2 
MHz operation. 

I found several of the above 
notes useful, especially AN- 127 
that told me how to fix my MP-09 
processor board. Also useful was 
AN-109, which provided informa- 
tion on using my MP-R 2716 pro- 
grammer on the 6809 system. 



Microcomputing, December 1981 129 



SINGLE BOARD 

COMPUTER 

$49.95 




The MASTER CONTROLLER 
BOARD contains: 

Z-80 Microprocessor: will run 
8080/8085 and Z-80 programs. 
72 - Parallel I/O lines; three 8255s 
Keyboard controller: 8279 
(also can control a 16 digit 
seven segment display) 
12K - EPROM: three sockets for 
2708,2716,2732, 
2K-RAM: 2114s 

8 - Sixteen bit counter timer 
channels: one 8253 and one 
AMD 9513 

2 - Serial I/O ports; one Z-80 SIO 
chip. One port has an RS-232 
interface and connector. 

1 - High speed arithmetic 
processor: AMD 951 1 or 
AMD 9512 

All the I/O chips are memory 
mapped AND I/O mapped. A 
bus expansion connector is 
provided. Can be operated on 
5 volts only. 

All this on one board less than 
nine inches on a side 

Only three LSI chips (Z-80, 8255, 

and EPROM) plus support gates 

and buffers are required for a 

working controller. 

BARE BOARD $49.95 
With documentation. 

MINIMUM KIT $99.95 Includes bare 
board with documentation, one each 
Z-80, 8255, 2708, two 2114s, and 
support gates and buffers, all socketed. 

MONITOR $39.95 This program allows 
a TTY or CRT to control the MASTER 
CONTROLLER. This program requires 
the minimum kit and monitor parts kit. 
A programmed 2708 is supplied with 
the MONITOR. 

MONITOR PARTS $54.95 

Includes 8253. Z-80 SIO, 1488, 1489, 
and connector. 

POWER SUPPLY $39.95 +5V1A, -5V 
V4A, +12V%A,-12V'/4A 

POWER SUPPLY $44.95 +5V 2A, other- 
wise same as above. 

Please include $2 postage and handling. 

OEM and dealer inquiries invited. 
VISA and MASTER CARD accepted. 

R.W. ELECTRONICS ^390 

3165 North Clybourn 

Chicago, IL 60618 

(31 2) "248-2480 



are on track 1, the disk head need 
move at most one track to get from 
the beginning of the directory to the 
end. Quite a difference. 

6809 Advantages over the 6800 

Having gone to a lot of effort to 
build a 48K 6809 system in addition 
to my present 50K 6800 system, there 
is the inevitable question of which I 
prefer. 

The 6809 is potentially more pow- 
erful, but not without quite a bit of 
additional expense. 

In the hardware area, my 6809 has 
about IV2 million bytes of storage 
with two disk drives. That could not 
be achieved with five-inch drives on 
my 6800 at all. 

The real potential of the 6809, of 
course, is in the software. Until re- 
cently, most 6809 software was sim- 
ply reassembled from original 6800 
source code, and thus had very little 
advantage over the 6800. For exam- 
ple, I recently wrote a spelling-cor- 
rection program called Magic Spell in 
6800 code, and then reassembled it 
for the 6809. The 6809 version runs 
10 or 20 percent faster, hardly enough 
to make much difference. 

Now, however, more and more 
software is being developed strictly 
for the 6809. Though the change can 
be seen in all sorts of application 
software, it is most apparent in sys- 
tem software such as disk operating 
systems. 

Though FLEX is by far the most 
popular, it does not really differ 
much from its 6800 version. But 
there are two other disk operating 
systems which run specifically on 
6809 systems. 

For big-system users (more than 
64K) there is UniFLEX from Tech- 
nical Systems Consultants (Box 2570, 
West Lafayette, IN 47906). This DOS 
is based on the famous UNIX system 
developed at Bell Laboratories, and is 
extremely capable. It is, however, 
definitely not for the small user. Not 
only is a very large amount of memo- 
ry required, but the UniFLEX man- 
ual even suggests that each UniFLEX 
installation requires a system 
manager to oversee it, and larger in- 
stallations may even require two 
such persons. 

A much more accessible DOS for 
the small user (though very usable 
on large systems as well) is OS-9 
from Microware Systems Corp. 
(5835 Grand, Des Moines, IA 
50312). OS-9 is actually available in 
two versions— Level 1 for systems 



under 64K, and Level 2 for systems 
over 64K. 

Both UniFLEX and OS-9 support 
multitasking and multi-user soft- 
ware, which makes them ideal for 
the business user who may want to 
have several operators working on 
the same data files. 

From the viewpoint of the hobbyist 
or personal computer user, their ad- 
vantage is less clear. While it might 
sometimes be convenient to do two 
things at the same time (edit an article 
while running a big BASIC program, 
for instance), this is not so important 
to the small user. 

A major disadvantage— at least 
from my point of view— is cost. 
Switching to a new DOS such as Uni- 
FLEX or OS-9 obsoletes all existing 
software. The cost of converting to 
either UniFLEX or OS-9, including a 
new DOS, BASIC interpreter, editor, 
assembler, text processor and per- 
haps other software as well, is in the 
area of $1000. 

Perhaps that explains why I decid- 
ed to keep my 6800 system and build 
a separate 6809 system. The two sys- 
tems give me the capability of run- 
ning two programs at the same time, 
and do it more cheaply than com- 
pletely switching to the 6809 and get- 
ting an advanced DOS. This way I 
have multitasking, multiprocessing, 
and multiprogramming (multi- being 
defined as two-). 

Besides, I like the 6800. ■ 



68xx Bulletin Boards 

There are currently three 68xx- 
based computer bulletin boards 
that I know of: 

904-477-8783 in Pensacola, FL, 
is run by Don Wright, and uses a 
tape-based 6800 system. Runs 
close to 24 hours a day. 

215-435-3388 in Allentown, PA, 
is run by Lehigh Press, and uses a 
disk-based 6809 system. Also 24 
hours a day. 

914-241-0287 in Mt. Kisco, NY, 
runs on either my 6800 or my 6809 
system, whichever is free at the 
time. This number is answered 
either by me or an answering 
machine during the day; the 
bulletin board program runs even- 
ings, usually until around mid- 
night. If you have any comments 
or suggestions for future articles, 
that's a good way of getting them 
to me. 

See you next time. 



130 Microcomputing, December 1981 








(without Front Panel Support) 

The H8/Z80 combination is nothing more than a glorified 8080 system unless you have the front 
panel monitor support to access the additional power of the Z80 CPU. The expanded instruction set, 
alternate registers and enhanced interrupt capability of the Z80 are all wishful dreams if inaccessible 
to the user. 

DG offers the H8 owner not only the finest Z80 CPU board available today but also the monitor 
necessary for its use. The DG-FP8 hardware/firmware package featuring our versatile FPM/80 
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monitor capabilities necessary for optimum utilization of the DG-80 Z80 CPU. 

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Features of the DG-80/FB-8 package include: 

Full compatibility with Heath® H8 hardware and software 

Expanded Z80 Instruction Set 

Operational 2 or 4 Mhz 

On-Board Provisions for 8K Prom or 4K Ram 

Hexadecimal or Split Octal Display and Entry 

Easy Front Panel Access to all Z80 Registers 

Support of H17 and H47/Z47 Disk System 

Support of CP/M V2.2 as well as HDOS 

AND MUCH MORE 

Complete Documentation Includes FPM/80, Source Listing, Mostek Z80 Programming Manual, 
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CP/M is a registered trademark of Digital Research of Pacific Grove, California. Heath, H8, & PAM8 are registered trademarks of the Heath Company. Z80® is the registered trademark of Zilog Corporation. 



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Ordering Information: Products listed available from DG Electronic Developments Co. , 700 
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without notice. 



t^See List of Advertisers on page 210 



Microcomputing, December 1981 131 



Let your digital machine tune into the analog world with this inexpensive, 

yet fast, multichannel analog-to-digital converter. 



The Best of Both Worlds 



By Gordon Wolfe 



What a marvelous thing the com- 
puter is! It can take numbers 
and add or subtract them, multiply or 
divide, perform all manner of func- 
tions, store them, manipulate them 
and spew them forth in a torrent of 
paper. Any mathematical operation 
on numbers that can be conceived by 
man can be performed by the com- 
puter. 

But where does the computer get 
its numbers to begin with? 

Suppose you, like me, were a scien- 
tist doing experiments involving 
measurements of electrical quantities 
from some sensor device. In the sim- 
plest case, you would read the quan- 
tity from a meter, enter it into your 
data book and later key it into the 
computer for analysis. The numbers 
are generated by the keyboard. 

But notice what happened— you've 
been reduced to an information col- 
lection and storage device for the 
computer. Computers should be our 
servants, not the other way around. 

It would be much more efficient if 
the computer itself could obtain the 
numbers directly from the measuring 
device. After all, they're both elec- 
tronic, aren't they? 

It turns out that such a thing is pos- 
sible, but that, generally, two such 
devices as a transducer and a com- 
puter are not fully compatible. The 
computer is a digital instrument, 
which recognizes only "on" or "off." 

We live in an analog world— very 
few measurements are "yes" or "no" 
in nature. For example, the output of 
an X-ray detector might be 8.0 V, 
meaning that a 12,000 V X-ray en- 



Address correspondence to Dr. Gordon W. Wolfe, 
1513 N. Sibley, Metairie, LA 70003. 



tered the detector. There are many 
other examples, such as the setting of 
a potentiometer or the output of a 
thermocouple, which give a voltage 
proportional to some physical value. 

The Conversion Process 

This voltage must be converted to a 
series of on-off signals that a comput- 
er can understand. This process is 
called analog to digital conversion, 
and is the centerpiece of any comput- 
er measurement system. 

There are several types of analog to 
digital converts (ADCs), with advan- 
tages and disadvantages to each. The 
single-ramp type is usually simplest 
and cheapest, but is slow in conver- 
sion and may suffer linearity prob- 
lems (see my article "Innovative 
Tech's Analog-to-Digital Converter," 
p. 176, December 1980). Double- 
ramp is faster, but more expensive. 
Successive approximation is the fast- 
est, most accurate and usually most 
expensive. 

The type of ADC used must be 



a) 




b) 



DETECTOR 




SIGNAL 



Fig. 1. a) Fast pulse whose amplitude is to be deter- 
mined, b) Source of the pulse— an ion depostis its 
energy in a detector. 



matched to the type of signal to be 
digitized. For dc signals, almost any 
type will do. For ac signals, such as 
speech recognition, a faster ADC will 
be required, with the speed require- 
ment increasing with the ac frequen- 
cy. Pulse height analysis, where you 
need to measure the maximum am- 
plitude of a short voltage pulse, has 
one of the most difficult require- 
ments. These types of pulses (Fig. la) 
are encountered often in science. In 
charge-particle physics, for example, 
a charged ion will deposit its energy 
(Fig. lb) in a detector (which is really 
just a reverse-biased diode) and cre- 
ate electron-hole pairs, which are 
seen as a pulse of current across the 
diode. The height of the pulse gives a 
measurement of the energy of the ion. 
The problem comes in measuring 
the maximum value of the pulse- 
how do you know when to take the 
measurement? Too soon or too late, 
and you miss the peak. Suppose your 
ADC has a conversion time of 500 ^s 
(microseconds), but the pulse is only 



(a) 

INPUT w/v- 



OTfcj 



CONTROL *\*- 



m 



OUTPUT 



(b) 



INPUT 



CONTROL 




OUTPUT 



Fig. 2. a) Sample and hold circuit, b) Peak holding 
circuit. 



132 Microcomputing, December 1981 



2 jis wide. What do you do then? 

Usually, the matter is taken care of 
by signal holding. The voltage to be 
measured is placed onto a capacitor, 
with no means of leakage off until the 
measurement is finished. If this is to 
be done at a specific time, a sample 
and hold circuit is used. If you want 
to measure a peak, you use a peak 
sensor circuit. Fig. 2 shows examples 
of each of these. 

Also, most ADCs have a comparator 
within them, which compares the in- 
put signal with some known fraction 
of a reference voltage. An ADC is on- 
ly as good as the accuracy of the com- 
parator and the precision of the refer- 
ence voltage. 

An Application 

The particular application I had 
was a combination of several types of 
data-taking, which required a fast 
"universal" analog-to-digital convert- 
er. My work at the University of Mis- 
sissippi is research into the make-up, 
production and transport of air pollu- 
tion. I do this by drawing large quan- 
tities of air through a filter, and ana- 
lyzing the filter with X-rays. Some- 
times the samples are liquified gases 
as well. 

The X-rays arrive at random times, 
and are transformed into electrical 
pulses whose height must be mea- 
sured. The energy spectrum is dis- 
played on an oscilloscope in real 
time, and sometimes modifications to 
the acquisition routines must be 
made while the analysis is going on. 
This is done by interacting with the 
display via a joystick, whose value is 



DUAL-IN-LINE PAO 

T7 




CLOCK 



TRI-STATE^ CONTROL 



TOP VIEW 



Fig. 3. Pin-out diagram of the A DC081 7 (courtesy 
National Semiconductor). 



displayed with the spectrum. 

So I need to measure two channels 
of pulse heights at random times as 
needed by incoming data, two chan- 
nels of dc voltages, on demand by the 
computer, and maybe one channel of 
temperature dc if liquid gases are 
involved. 

What I really need, then, is an ADC 
that can do dc or pulse height, whose 
function can be started by the experi- 
ment or by the computer, with at least 
256 channels of resolution (eight-bit 
output). With 5-V signals, this means 
accuracy to about plus or minus one 
millivolt. Also, I need a conversion 
time less than 100 ps. 

Such devices are on the market. 
One made specifically for the pur- 
pose outlined above sells for $1650, 
and $475 for the precision power sup- 
ply. Too much for my pocket book. I 
was determined to build my own. 



ADC 

SSB MNEMONIC ASSEMBLER PAGE 1 



NAM ADC 
OPT MOP 

♦HANDLER FOR ADC8817 
♦CIRCUIT WITH 15 COMPUTER 
♦SELECTABLE INPUTS, 7 
♦EXTERNAL SELECT INPUTS 



ft020 
8018 

DA80 



XTEMP EQU 
PIAADC EQU 



*AO20 
$8018 



org *oaee 

♦ROUTINE TO CALL DATA 
♦INPUT CHANNEL 
♦CHANNEL NO IN A 

DA88 81 8E CALDflT CMP A #14 

DA82 2E 68 BGT ERROR 

DA84 48 ASL A 

DA85 48 ASL A 

DA86 48 ASL A 

DA87 48 ASL A 

DA88 B7 8818 STA A PIAADC 

DA8B 86 FF LDA A i$FF 

DA80 87 8818 STA A PIAADC 

DA16 3E MAI 

DA11 39 RTS 

♦PIA INITIALIZATION 
♦A SIDE 8-3 INPUT 
♦A SIDE 4-7 OUTPUT 
♦B SIDE INPUT 
♦C81 INTERRUPTS ON 
♦HIGH TO LOU TRANSITION 

* 



DA12 
DA15 
DA17 
DA19 
DRIB 
DA1D 
DA1F 
0A21 
DA23 
DR25 
DA27 



CE 8818 
6F 88 
€F 82 
86 F8 
A7 88 
6F 82 
86 84 
A7 81 
86 85 
A7 83 
39 



ADCSET LDX 
CLR 

cut 

LDA A 
STA A 
CLR 
LDA A 
STA A 
LDA A 
STA A 
RTS 



IPIAADC 

e,x 

2,X 
§fF8 

ax 

2,X 
•*84 

1*X 



XX 



♦INTERRUPT SERVICE ROUTINE 
♦EXECUTES ONE OF 15 



I had begun to design such a device 
when I ran across an advertisement 
for the National Semiconductor ADC 
0817 integrated circuit. (See Figs. 3 
and 4.) This chip is designed to be the 
centerpiece of a data acquisition sys- 
tem such as mine. It has eight-bit res- 
olution with tri-state outputs, fast 
successive approximation conversion 
methods and a 16-channel analog 
data multiplexer so that up to 16 ana- 
log channels may be digitized. Best of 
all, it has a conversion time of only 90 
fis at the 875 kHz clock rate I use, and 
a whole acquisition system may be 
constructed for less than $70. 

The circuit I eventually came up 
with is shown in Fig. 5. Fifteen of the 
sixteen analog inputs are usable. 
Seven inputs are controllable by ex- 
ternal strobes, and eight are con- 
trollable by the computer through 
data lines PA4 through PA7. The only 



DA28 

DA28 
DA2A 
DA2C 
DA2E 
DA38 
DA32 
DA34 
DA36 
DA38 
DA3A 
DA3C 
DA3E 
DA46 
DA42 
DR44 

DA46 
DA47 
DR4A 
DA4C 
DR4F 
DA52 
DA53 
DA56 
DAS8 
DR5B 
DA5E 
DA68 
DA61 



OS 88 
DA 68 
DA 68 
DA 66 
DA 68 
DA 66 
DA 68 
DA 68 
DA 68 
DA 68 
DA 68 
DA 68 
DA 68 
DA 68 
DA 62 

8F 

B6 8818 
84 8F 
CE DH28 
FF A828 
48 

B8 A821 
24 83 
7C A828 
FE A828 
AD 88 
8E 
38 



♦OEPENDING ON ADOR 
♦IN PIAA 8-3 

TABLE EOU ♦ 

R0UT8 FDB $0988 

R0UT1 FOB DONE 

R0UT2 FDB DONE 

R0UT3 FDB DONE 

R0UT4 FDB DONE 

R0UT6 FDB DONE 

R0UT7 FDB DONE 

ROUTS FDB DONE 

R0UT9 FDB DONE 

ROUTA FDB DONE 

ROUTE FDB DONE 

ROUTC FDB DONE 

ROUTD FDB DONE 

ROUTE FOB DONE 

ROUTF FDB ERR0R2 

* 

DATAIN SEI 

LDA A PIAADC 
AND A i$8F 

LDX iTABLE 
STX XTEMP 
ASL A 

ADD A XTEMP+1 
BCC SERVE 
INC XTEMP 
SERVE LDX XTEMP 

e,x 



DONE 



JSR 
CLI 
RTI 



DR62 28 FC ERR0R2 BRA 
DH64 39 ERROR RTS 

END 
MO ERROR(S) DETECTED 



DONE 






SVMBOL TABLE: 
RDCSET DA12 
DM6 DONE 



ERROR 

8018 
R0UT1 

WEE 
R0UT6 

0A36 
ROUTA 

DA3E 
ROUTE 

DflSB 
XTDP 



DA64 

R0UT8 
0A2A 

R0UT4 
DA32 

R0UT9 
DA3A 

ROUTD 
DA42 

TABLE 
A028 



CALDAT 

DA68 
ERR0R2 

DA28 
R0UT2 

DA38 
R0UT7 

DA38 
ROUTB 

DA48 
ROUTF 

DA28 



DA06 
DA62 
DR2C 
DA34 
DA3C 
DA44 



DATAIN 

PIAADC 

R0UT3 

R0UT8 

ROUTC 

SERVE 



Listing 1. ADC program for a 6800-based system. 



Microcomputing, December 1981 133 



input that is not usable is number fif- 
teen, corresponding to input pin 
IN 15, which is address 1111 from the 
A-side of the PIA. Sending a 1111 
from PIA lines PA4 through PA7 will 
have no effect. 

The ADC 0817 (IC8) does the ma- 
jority of the work. It does the analog- 
to-digital conversion of the analog in- 
put whose hexadecimal channel num- 
ber is presented at the address inputs. 
The data outputs and an end-of-con- 
version signal are sent to the B-side 
inputs of a 6820 PIA. 

IC10, the IN914 diode, capacitor 
and transistor form a peak-sense-and- 
hold amplifier on the output of the 
analog multiplexer. The capacitor is 
charged by IC10 to the maximum 
voltage of the input being sampled, 
and since there is effectively no leak- 
age current, will maintain this volt- 
age at the input of the ADC until the 
end of the conversion, when the tran- 
sistor shorts the capacitor to ground. 
Do not substitute for IC10. Most gen- 
eral-purpose op-amps and compara- 
tors are simply not fast enough for 
this application. 

IC5 is the precision voltage refer- 
ence for the ADC. It is an analog de- 
vices AD584 chip, and can be pro- 
grammed for 10.000, 7.500, 5.000 or 
2.500 V, plus or minus one millivolt. 
It is essentially a precision, low- 
power voltage regulator. You might 
be tempted to use this chip as a 
power supply for the whole conver- 



sion circuit, but that isn't a good idea. 
The AD584 can only source or sink 
up to 15 mA, and precision suffers 
above 10 mA. In this circuit it is used 
only for power and reference voltage 
for the ADC 0817, and supplies only 
1 mA. 

IC2, IC6 and IC7 form a series of 
one-shots and flip-flops which start 
the conversion process, give a busy 
signal which can be used to prevent 
further data coming in during the 
conversion, set the address latch, 
and which are reset by the end-of- 
conversion pulse. 

IC1, IC3 and IC4 sense that a data 



conversion is required, either by the 
computer or by the incoming data, 
and set the address latch onto the 
ADC so that the correct analog input 
may be used. Inputs 8-14 may be ac- 
cessed by the experiment directly, 
while inputs 0-14 may be accessed 
by the computer. IC2 starts the con- 
version process whenever a high-to- 
low transition is seen at any of its in- 
puts, assuming that ail were high to 
begin with. The 2N2222 transistors 
on the inputs of IC1 are invert-buf- 
fers. In my applications, the "data 
present" strobe is usually + 10 V, and 
these invert the signal and convert it 
to TTL levels. IC1 is a priority encod- 



COMPARATOR IN °- 



COMMON o- 



16 ANALOG INPUTS - 



16 CHANNELS 
MULTIPLEXING 
ANALOG 
SWITCHES 



START 
o 



8-BIT A/D 

I 



4 BIT ADDRESS - 



ADDRESS LATCH ENABLE 
EXPANSION CONTROL 



7*> 

La 



ADDRESS 
DECODER 



CLOCK 

ii 



CONTROL 
5 TIMING 




-° END OF CONVERSION 



S A R 



COMPARATOR 



LA 







SWITCH 
TREE 



I 



n 



TRI 

STATE ® 
OUTPUT 
LATCH 
BUFFER 



255R 

RESISTOR 

LADDER 



I 



- 8 BIT OUTPUTS 



VCC GND REF(+) REF(-) TRI-STATE CONTROL 

Fig. 4. Block diagram of the ADC081 7 (courtesy National Semiconductor). 



TO 
MICR0PR0CESS0 
BUS 




Fig. 5. Circuit diagram of ADC0817 in use in present work. 



134 Microcomputing, December 1981 



er so that Jl has highest priority; the 
most important signals should go on- 
to Jl. If a signal is present at J2, and a 
signal comes into Jl, the conversion 
will switch to Jl. 

A four-bit code is sent to the proces- 
sor via the lowest four bits of the 
A-side of the 6820 PIA to tell the com- 
puter which input of the ADC is be- 
ing converted. This is necessary for 
one of the strobed inputs, and is a 
good confirmation that the correct 
computer-controlled input is being 
accessed. To access an input, simply 
output the four-bit address of the in- 
put channel through the higher four 
bits of the A-side of the PIA. 

Notice that we are using the PIA as 
12 inputs and four outputs. The 6820 
is designed so that all bits of either 
side can be programmed by the com- 
puter to be either input or output. In 
this case, the B-side is all input, while 
the A-side is half input and half 
output. 

Users of SS-50 systems who have 
the MP-LA parallel input/output card 
must make a minor change in the 
card. This card is set up so that all of 
the B-side is input and all of the 
A-side is output. Cutting two tracks 



and adding two wires, as shown in 
Fig. 6, will reverse the buffers on the 
lowest four bits of the A-side and 
make those four bits inputs. A DPDT 
switch can be glued to the card to 
switch back and forth. 

Lastly, the converter is dependent 
upon a high-frequency square wave 
clock, which is to be input to pin 22 
of the ADC 0817. This clock should 
be between 600 kHz and 1200 kHz. 
In my SWTP 6800 system, I simply 
use the 875 kHz 01 clock line. 




ADD THESE WIRES 



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Fig. 6. Modifications to the MP-LA output port. 



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Microcomputing, December 1981 135 



Since the converter is designed to 
digitize data which arrives at random, 
unpredictable times, the converter 
has been set up to cause an interrupt 
in the processor. In the case of a 6800- 
based machine, this should be a non- 
maskable interrupt (NMI). The out- 
put of pin 37 of the PIA should be tied 
to the NMI line of the processor bus. 

ADC Programs 

The software used with the con- 



verter should reflect the 15-input na- 
ture of the converter, and should also 
be able to be used as an interrupt ser- 
vice routine, since the end-of-conver- 
sion signal causes an interrupt. An 
example of the type of software to be 
used in 6800-based systems is given 
in Listing 1. 

This software is in two major parts: 
Routine CALDAT at $DA00 is a sub- 
routine which puts out a number be- 
tween and 14 from accumulator A 



ICNo. 


Type I 


1 


74147 


2 


7420 


3 


7400 


4 


7475 


5 


AD584 


6 


7400 


7 


7400 


8 


ADC0817 


9 


7404 


10 


LM310A 


11 


MC6820 


•See Text 





Table 1. 



+ 5 V 




+ 15 


-15 


Power 


Ground 






16 


8 






14 


7 






14 


7 






5 


12 






— 


4 


8 




14 


7 






14 


7 






* 


20,23 






14 


7 






— 


— 


7 


4 


20 

md conm 


1 
actions for in 


teerated 


circuits. 



to begin a conversion on data lines 
to 14. The routine starts the conver- 
sion, waits for the data, services the 
interrupt, and returns to the calling 
program. The other routine, DATAIN 
at $DA46, is the interrupt service 
routine. The routine accepts the data 
from the PIA, gets the address of the 
input channel in box, and branches to 
one of 15 service routines to store 
the data or operate on it. A different 
routine is provided for each of the 15 
usable channels, since the usual pro- 
cedure will be that each channel 
means something different. 

An example of such a service rou- 
tine is given in Listing 2. In this case, 
a histogram is generated, to give the 
number of times a specific voltage is 
seen versus the voltage itself. If the 
voltage measured corresponds to, for 
example, the energy of an X-ray, then 
the histogram is a plot of the number 
of X-rays seen vs energy of X-rays. 
Such a histogram is plotted in Fig. 7. 

If you use the program above, or a 
similar program, with your machine, 
be sure that the nonmaskable inter- 
rupt vector is programmed to trans- 
fer control to the interrupt service 
routine DATAIN. 



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136 Microcomputing, December 1981 



The programs above are not relo- 
catable nor re-entrant, and may not 
be placed in EPROM, since they are 
self-modifying. It would have been 
easy to write the routines to meet 
these criteria, but speed of execution 
would have suffered greatly. Since 
my uses require up to 1000 conver- 
sions per second, the speed of the ser- 



HISTO 

SSB MCM0N1C ASSEMBLE* PAGE 1 



NflH HISTO 
OPT NOP 

♦INTERRUPT SERVICE ROUTINE 
♦TO CREATE HISTOGRAM 
♦OF FREQUENCY VS CHANNEL 



D98B 

D986 
8018 



ORG $0906 



HISTGH EOU 

PIAAOC EQU 

* 



A 
A 



D988 BS 881A LW 

D983 B? D96A STA 

D966 FE D886 LDX 

D9e9 6c m JUMP IMC 

D9tt 39 RTS 

* 

END 
NO ERROR(S) DETECTED 



Listing 2. 



18018 

PIAADC+2 

JlfF+1 

HISTGM 



vice routine is paramount, or data 
will be lost. The creative programmer 
with less stringent requirements can 
easily rewrite the programs to his 
own needs. 



No matter what your analog-to- 
digital conversion needs, this circuit 
can solve them for you, with a 
minimum of cost, parts count and 
programming. ■ 



6400 



3600 



</> 



3 
O 
O 



1600 



400 



URBAN AEROSOL SAMPLE 
MYLAR BLANK 




8 10 

ENERGY (KEV) 



12 



14 



16 



Fig. 7. Histogram of frequency of occurrence of a given value of the ADC data vs the value of the data. To 
be specific, in this case, X-ray intensity vs X-ray energy. Notice the peaks showing up nicely, correspond- 
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Microcomputing, December 1981 137 



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Principle of Operation: The ELECTRIC MOUTH stores the digital equivalents 
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ports (user selectable) are used 

SPOKEN MATERIAL INCLUDED (Vox I) 



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have mile 


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DeptK8 
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■ D Elf II "Electric Mouth" kit w/Vox I $ 99.95 

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■ D TRS-80 Level II "Electric Mouth" kit w/Vox I $119.95 

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138 Microcomputing, December 1981 



Ever tried to read computer sales literature? 

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Ever tried to make a decision about 

which computer to buy? 



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31DB7 







This series' concluding article puts into perspective the growing Japanese presence in the microcomputing 

marketplace and its effect on the American consumer. 



Japanese Invasion: Part IV 



By G. Michael Vose 



It does not now appear that the 
Japanese are going to flood the 
small computer market with awe- 
some machines priced like fast 
food— at least not for a year or more. 
The computers reviewed in Parts I, II 
and III of this series (the Casio FX- 
9000P, September, p. 101; the Sharp 
YX-3200, October, p. 90; and the 
NEC PC-8000, November, p. 110) are 



expertly designed and well-made but 
are not appreciably better than 
homegrown machines. And while 
they are competitively priced, they 
do not significantly undercut the 
prices of American manufacturers. 
So how do we evaluate the invasion 
we speak of in the title of this series? 
Ultimately, the Japanese may over- 
whelm the American market by 



1 





sheer number— number of manufac- 
turers and number of machines. The 
Japanese, in spite of the seeming 
socialistic benevolence of their in- 
dustrial organizations, are fiercely 
competitive. This is true of the 
worldwide marketplace, but it is 
especially true in Japan. While most 
Japanese companies would like to be 
among the top companies in the 
world, they would like even more to 
be number one in Japan. This com- 
petitiveness, combined with 
Japanese electronic expertise, will 
guarantee that the peoples of this 
small Far Eastern island will be 
responsible for significant advances 
in computer technology. 



Many Little Companies 
All in a Row 

Our series so far has looked at new 
computers from three of Japan's most 
aggressive electronics conglomer- 
ates. A survey of the industry in 
Japan reveals, however, that no 
fewer than 25 companies are manu- 
facturing and selling micro- and mini- 
computers. Several of these firms 
also market mainframe computers. 
These machines cover the gamut 
from a unit with a 4K byte user mem- 
ory and a Z-80A CPU to units with a 



*.»*/**/^ 



G. Michael Vose is a technical editor for 
Microcomputing. 



140 Microcomputing, December 1981 



256K byte user memory accessed by 
a 16-bit Intel 8086 processor. In- 
between are units with twin 6809 
CPUs to computers designed around 
the Motorola 68000 processor that 
can function in either a 16-bit or a 
32-bit environment. 

Interestingly, the Japanese have 
never used the 6502 CPU in mass- 
marketed machines. The Motorola, 
Intel and Zilog microprocessors have 
been the building blocks for Japanese 
engineers. 

The names of many of the Japanese 
companies now making microcom- 
puters—Canon, Casio, Hitachi, NEC, 
Sanyo, Seiko, Sharp, Toshiba— are fa- 
miliar to both Americans and Euro- 
peans. Others such as Oki, SORD, 
Anritsu and Densan are less familiar. 
They all have a common thread, 
however— a history of manufacturing 
success and some experience with 
electronics. This is in direct contrast 
with the American method of build- 
ing hardware. 

In the U.S., a new hardware idea 
usually means a new company. A 
new company very often is started by 
an engineer with a great new idea, 
very often with a prototype of the 
hardware system he has designed. 
The engineer usually doesn't know 
much about marketing, manufactur- 
ing, organization and the other com- 
ponents of business operation. Un- 
less he can find and afford compe- 
tent, knowledgeable managers, his 
project may never succeed. The idea 
may eventually catch on, but often 
the engineer who developed it loses 
out. 

In Japan, the engineer is committed 
to the company he works for. A great 
new idea makes the company look 
good and, as a result, many people 
benefit. The manufacturing and mar- 
keting support are in place to assure 
the successful implementation of the 
technology. The risks are shared as 
we\\ as the rewards. 

In America, established electronics 
firms such as RCA, Sylvania and 
Magnavox have made no attempt to 
develop new technology like comput- 
ers. Even Radio Shack, the electron- 
ics firm that made available the first 
low-priced, mass-marketed micro- 
computer, took on the new project 
with skepticism and with no expecta- 
tion of success. Radio Shack did not 
commission the development of the 
first TRS-80: it merely bought the 
idea after the fact. Zenith Corpora- 
tion acquired Heath Company after 



its computer had been developed— 
this deal was struck more for eco- 
nomic reasons than any other. 

What does this mean to the long- 
range future of the microcomputer 
market and the Japanese role in it? 
The Japanese have demonstrated that 
they have the expertise to make a 
quality small computer. In just the 
four years since the Apple and 
TRS-80 were developed, the Japanese 
have developed the Sharp Business 
Computer and the NEC PC-8000. 
These machines are just as good as 
their American counterparts and on- 
ly slightly more expensive. 

The Japanese have heard the cry, 
"What about software?" and are 
striking deals with software compa- 
nies and making machines that are 
compatible with existing operating 
systems and software libraries. The 
Japanese are skilled in marketing 
concepts. (For example, NEC has just 
announced that its new PC-8000 sys- 
tem will be sold by the new Sears 
Business Systems Centers, which 
began opening around the country in 
October.) 

The Japanese are capable, competi- 



tive and have a strong industrial base. 
They will obtain a share of the 
market and will develop new and 
better machines. 

The Invasion Continues 

Ironically, the rapidly growing 
Japanese presence in the microcom- 
puter marketplace has the effect of 
confusing an already blurred land- 
scape. The prospective buyer of com- 
puter equipment, whether a busi- 
nessman or a home-computer buyer, 
must wade through an expanding 
selection of units, all claiming to be 
the best. Ten years from now, the 
chore will be easier because many 
shoppers will know what they want 
or need and will be able to narrow 
the field before they start. But today, 
many people know that they want or 
need a computer, but they are not 
sure why. 

And the selection grows. Sharp 
Corp., in addition to its YX-3200 
Business Computer, markets the 
MZ80B in Europe. Oki Corp. sells the 
IF800 (Models 10, 20), a Z-80 based 
machine with 48K bytes of user 
memory, 8K bytes of prepro- 



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^302 



Microcomputing, December 1981 141 



grammed systems memory and 
graphics with color capability. Mat- 
sushita Company offers the Mybrain 
850M monochrome display com- 
puter operating with an 8085 (eight- 
bit) processor and featuring 56K 
bytes of user memory. 

Densan Co. Ltd. makes available a 
terminal-dependent unit called the 
DSC-80ZA, containing a Z-80A or 
8088 (eight-bit) processor. Canon of- 
fers a pair of 6809-based machines, 
the BX-3 and CX-1, each with 32K 
bytes of user memory. 

Other manufacturers now selling 
microcomputers only in Japan are 
eyeing the rapidly developing Ameri- 
can market. TEAC sells a Z-80A- 
based, 48K byte monochrome dis- 
play microcomputer; Hitachi offers a 
6809-based color computer with 64K 
bytes of user memory for the 
equivalent of $1355; and Sanyo 
wants to become the OEM for any 
American firm interested in offering 
a 64K byte memory microcomputer 
fired by dual 8085A processors. 

Most of the Japanese microcomput- 
ers contain a BASIC language inter- 
preter and many offer optional pack- 



ages to allow the use of COBOL, 
FORTRAN and Pascal. Many have 
operating systems similar to and 
compatible with CP/M. Most are 
S-100 bus constructed, assuring por- 
tability and compatibility with other 
computer systems. 

The Japanese are diligent; they 
know what other people are doing 
and they are quick to adapt to what 
they see as a standard. 

Who's the Best? 

Is there someone who can tell you 
which computer is right for you? On- 
ly one— you! The name of the game is 
figuring out what you want to do, 
now and in the future, and then look- 
ing at machines and software that 
will do the job for you. Don't be 
afraid to be subjective— looks and 
ergonomics are as important as maxi- 
bytes and operating systems, color 
and graphics as important as price 
and serviceability. There seems to be 
no easy way to choose— it is helpful 
to learn as much as you can about 
machines with a big reputation (see 
the IBM and Xerox reviews else- 
where in this issue). 



It is true that the computer you buy 
today will no doubt be dwarfed by 
the computers of tomorrow. But if to- 
day's computer does its job, it is 
nevertheless a valuable tool. The 
Japanese intend to see that you get a 
broad and capable choice. 

The One Question 

The Japanese do have one weak- 
ness that will affect their impact on 
the American market. They do not 
have the resources to produce inno- 
vative software for the U.S. con- 
sumer. The experience of VisiCalc 
and its effect on the sales of the Apple 
Computer, the first computer for 
which it was written, is a classic ex- 
ample of how top-quality software 
can boost hardware sales. While 
there is no way to evaluate this 
phenomenon, there is no question 
that software support helps to sell 
hardware. 

If the Japanese can entice top soft- 
ware producers into writing for 
them, they will significantly enhance 
the market for their machines. Then 
it will be time to evaluate the 
Japanese Invasion, Phase Two.i 



Your Pascal too slow? 

Not anymore . . . 



wirh rhe PASCAL SPEED-UP KIT, which includes THE MILL: rhe easiest 
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You now have a 30 to 300% faster Pascal P-machine. and you 
don't have to recompile, reprogrom or relink. FORTRAN users may 
also take advantage of THE PASCAL SPEED-UP KIT. Contact your 
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THE ASSEMBLER DEVELOPMENT KIT 

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THE MILL transforms the 8-bit Apple II 
info a computer that octs like a 
1 6-bit machine THE Mia has 
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permit the 6809 to run at full 
speed (1 megahertz) ond 
allow rhe 6502 to run at 
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speed — 
AT THE SAME TIME! 





Find out about 
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^179 



142 Microcomputing, December 1981 



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Microcomputing, December 1981 143 



Does your SWTP need more room to move? The QRC motherboard is the solution to system expansion. 



Relief for an 
Overstuffed SWTP 



By Dennis Doonan 



It was bound to happen. My SWTP 
6800 chassis was filled. Even the 
eight I/O slots were filled with 
boards. While it is nice to have a full 
system, it is uncomfortable to know 
future expansion will cause drastic 
changes. 

I could replace three memory cards 
with a single 32K card. This would 
open two main slots and ease the load 
on the power supply, but the cost of 



Address correspondence to Dennis Doonan, do 
Graphics I, 345 Main St., Racine, WI 53403. 



replacing three reliable products 
would be hard to justify. 

The only sensible alternative was 
to expand the motherboard. The pro- 
cedure is described in the SWTP sys- 
tem manual; just buy another moth- 
erboard and connect it in parallel 
with the existing one. 

This sounds simple, but there are 
two problems. SWTP no longer 
makes the MP-B2 motherboard. 
Even if a used one could be found, it 
would have the same I/O addresses 
as the first one. Rewiring would be 
necessary. See the April 1980 issue of 
Microcomputing ("The SWTP Com- 



puter System,' p. 136) for an expla- 
nation of the re-addressing pro- 
cedure. 

The decoding on both boards 
would also have to be changed or a 
full 8K of address space would be 
needed for the I/O ports. This 
couldn't even be considered on a 
system limited to 64K. 

About the time I was faced with 
these problems, Quality Research 
Company (PO Box 7207, Spokane, 
WA 99207) announced their 80-210 
motherboard for the SS-50 bus. It was 
designed with expansion capability 
in mind. 











Photo 1. The completed QRC 80-210 motherboard. It can be used as is for a Photo 2. The extender card that fits onto the existing SWTP chassis. The two 
single system or used as an expansion motherboard. ribbon cables go to the QRC extension board. This is the back view of the board. 

144 Microcomputing, December 1981 



The Package 

The QRC 80-210 is a double- sided, 
plated-through board physically 
compatible with the SWTP mother- 
board. It provides seven main 50-pin 
slots and eight fully decoded 30-pin 
I/O slots. All of the data, address and 
control lines have interbus shielding 
and buffering. There is even ground 
plane shielding on the top of the 
board. These shields provide the 
lower signal noise level essential for 
expansion. 

The price of the 80-210 bareboard 
is a reasonable $39.50. QRC provides 
the pin connectors for an additional 
$20. 

The QRC documentation is clear 
and concise. It gives assembly in- 
structions, a parts layout, schematic 
and theory of operation. 

Connection 

Assembly takes about one hour, 
but care should be used to keep the 
pin connectors straight when solder- 
ing. If they are installed at an angle, it 
is difficult to insert boards. It is best 
to solder each end of the individual 
10-pin connectors and make sure 
they are straight before soldering the 
rest of the pins. 

The board is delivered with the I/O 
addressed at 8000 (hex). Since the 
eight four-byte I/O ports are fully 
decoded, they use only 32 bytes of 
the memory map and can be ad- 
dressed to any location. 

The I/O address decoding can be 
selected by jumpers or DIP switches. 
The switches allow easy reconfigura- 
tion if a 6809 processor card is ever 
installed. 

The I/O ports on the SWTP 6800/2 
use partial decoding. The 32-byte ad- 
dress pattern is repeated after 32 
bytes of free address space for the en- 
tire 4K block. The easiest way to use 
the QRC board is to address its I/O at 
$8020 so it fits between the addresses 
used by the SWTP motherboard. 
There are now 16 I/O ports available 
on the system. 

Ports zero through seven can be 
used without modifying existing soft- 
ware. If the other eight ports are 
needed by a high-level language such 
as BASIC, they can be called from a 
machine-language routine (the user 
function in BASIC). 

The 50-pin bus of the 80-210 is ex- 
pandable through two 50-pin stan- 
dard connectors (AMP 2-87227-5) on 
the front edge of the board. Two 
50-wire ribbon cables go to the sec- 




Fig. 1. This is a full-sized etch guide that can be used for etching the extender card. The center points for 
drilling are not included on this layout. 



ond motherboard. While SWTP rec- 
ommends #18 wire for the extension, 
ribbon cables will be adequate if they 
are kept short. 

The only problem remaining is to 
connect the cable to the SWTP moth- 
erboard. The wires can be soldered 
directly to the original motherboard, 
but it is easier to use a short extender 
card ending in an AMP connector 
matching the ones on the QRC board. 



Fig. 1 is a full-size etch guide for the 
extender. Conventional Molex con- 
nectors are used at the bottom and 
two AMP pin connectors are used at 
the top. The +8V line is not connect- 
ed. A jumper may be installed if 
needed. 

If your original power supply is not 
overloaded, it can power the expan- 
sion motherboard. Power and control 
lines are brought to the side of the 

Microcomputing, December 1981 145 













/ 




Photo 3. This is the unpopulated QRC motherboard and extension cable/ex- 
tender card ready to plug into the SWTP. 



Photo 4. The QRC motherboard as it arrived with bare board documentation 
and pin connectors. 



QRC board. The power supply 
should be connected directly to these 
points rather than through the exten- 
sion cables. 

If your system's power supply is 
weak, a second supply can be con- 
nected to the expansion mother- 
board. If this is done, cut the + 12 and 
- 12 V traces on the extender board. 
Be sure the ground leads are con- 
nected between the two boards. 



When using the ribbon cables, be 
sure the connectors are seated prop- 
erly to ensure a tight fit. Also, before 
applying power, be certain the con- 
nection between the two boards is 
correct. If either the extender or the 
cables are inserted incorrectly, a 
great deal of damage could be done. 
This caution is necessary since the ex- 
tender card was designed to have the 
foil traces on the top of the board. 



This allows more room in the chassis. 
The expansion is definitely worth 
the trouble. It is now possible to use 
old 4K memory boards and address 
them to unused areas such as 9000. 
I/O boards and custom interfaces can 
be added without removing existing 
boards. The Quality Research Com- 
pany's 80-210 has proved to be a reli- 
able, reasonably priced solution to 
system expansion. ■ 



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MICRO & PERSONAL COMPUTER is the ideal media 
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y*See List of Advertisers on page 210 



Microcomputing, December 1981 147 



Z-charting helps businessmen evaluate the performance of their business by studying the shape of their Z. 

Programmers will find this method of manipulating data arrays intriguing. 



In Search of the Perfect Z 



By Gene Embry 



The Z-charting technique for eval- 
uating the performance of a busi- 
ness is rather obscure. But once you 
understand Z-charts, a quick glance 
will reveal several basic facts about 
the performance of a company. Pro- 
grammers will find it an intriguing 
method of manipulating data arrays. 

Fig. 1 shows a Z-chart. The vertical 
axis is labeled Dollars and the 
horizontal axis is Time. The bottom 
horizontal bar of the Z is a plot of the 
planned monthly bookings. The top 
bar of the Z shows the accumulated 
bookings for the past 1 1 months plus 
this month's bookings. The diagonal 
shown as the dashed line represents 
the year-to-date ( YTD) planned book- 
ings. The diagonal shown by the solid 
line represents the YTD bookings. In 
the very unusual case where book- 
ings are equal to the plan, then only 
one line would be shown for the 
diagonal. 

A programmer might think of the 
Z-chart as a 4 x 12 data array— 12 data 
points for each part of the Z-chart. 
For each month there may be up to 
four different data points. 

The interpretation of the Z-chart 
deals with the shape and not with the 
absolute values. Consider the four 
cases that are shown in Fig. 2. The 
first Z-chart, Fig. 2a, represents a no- 
growth company where the monthly 
plan and monthly bookings are the 

Address correspondence to Gene Embry, Route 1, 
Box 151-H, Morrisville, NC 27560. 

148 Microcomputing, December 1981 



same, year after year. Fig. 2b shows a 
growing company with a monthly in- 
crease of about 5 percent and with 
monthly bookings equal to the plan. 
The third, Fig. 2c, shows a company 
with a planned declining situation. 
This might represent a planned with- 
drawal from a marketplace. The final 
example, Fig. 2d, shows a situation 
where bookings are lagging the plan 
by about 50 percent, a very un- 
healthy situation. The demise of this 
company is near. (These four cases 
should serve only to introduce you to 
Z-charts, and not all possible situa- 
tions.) 

The business with a perfectly 
shaped Z, Fig. 2a, would not be given 
a perfect 10 by those with business 
acumen. But today's managers gener- 
ally stress growth while maximizing 
gross return on net investment 
(GRONI). Current business theories 
are generally based on a time when 
our society was primarily oriented 
toward manufacturing. Within the 
last two or three years, we've become 
mainly service-oriented. Could it be 
that yesterday's theories are only par- 
tially correct? A normal Z (Fig. 2a) 
may, in fact, be a reasonable and de- 
sirable goal. If you can take $100,000 
out of your business, year after year, 
and you are satisfied, why shouldn't 
that business be considered healthy? 

Note the positive slopes in Fig. 2b 
for the growth company and the neg- 
ative slopes for the declining business 
in Fig. 2c. Fig. 2d shows convergence 



of the two bars, indicating aggressive 
planning but declining bookings. 

These four examples show that sev- 
eral important aspects of a business 
may readily be attained from a 
Z-chart. Two items not initially ap- 
parent from the Z-chart are the in- 
creased need for cash when the book- 
ings begin to outstrip the plan, and 
the need to replace the planners or 
salesmen when bookings lag the plan 
by some unacceptable amount. 

You don't need to restrict the verti- 
cal axis to dollars. It might be 
anything that is important to your 
business; e.g., the number of pages of 
advertisements in a magazine or pro- 
ductivity (dollars invoice per employ- 
ee) time. 

The program, ZCHART.BAS (List- 
ing 1), can do much more than plot a 
Z-chart. It will let you start your own 
company and insert your own month- 
ly plan and bookings for a 20-year 
period. You can automatically gener- 
ate 20 years of data based on random 
numbers. You can list the entire 20 
years of data or just one year's data. 
Further, you may save the data on 
disk or retrieve it from disk. 

I've written the program in a mod- 
ular form so that you can select only 
those portions you want to use. If you 
don't have a disk, you can insert a 
subroutine, starting at line 5000, to 
get your data from magnetic tape or 
from data statements. 

Each of the seven main subroutines 
begins on a line number that is an in- 



teger of 1000 and returns on a line 
number that is an integer of 1000 plus 
90. I'll first discuss the program ini- 
tialization process and the generation 
of the main menu section, and then 
describe each of the seven major sub- 
routines. The program is fairly well 
documented with remark statements, 
so I'll only describe certain items in 
the program that are interesting or a 
bit unusual. 

Initialization 

The program variables are initial- 
ized by the call to routine 9800. The 
main function of this routine is to di- 
mension the arrays and assign certain 
variables. A listing of the major arrays 
and variables are shown in Table 1 . 

During this section, you are 
prompted to input the y-axis resolu- 
tion. Your answer to this question de- 
termines the size of the plotting ar- 



c/> 




TIME 



Fig. 1. The Z-chart defined. 



< 
-i 

§ 




TIME 



Fig. 2a. Z-chart for a no-growth company. 



1 

-i 

2 




TIME 



Fig. 2c. Z-chart for a planned withdrawal. 



ray, Z(R,12). Since the program pro- 
vides for automatic scaling of the 
y-axis, your answer will, in effect, 
determine the length of the y-axis. If 
you exceed the size of your read/ 
write memory, then the error trap- 
ping section, line 9990, will be 
invoked. 

The main menu is displayed via 
lines 100 to 140. Your selection is re- 
quested and the particular subrou- 
tine is called from lines 170 to 199. 

MAKE DATA— 1000. If you elect to 
generate some random data, this sec- 
tion is called. We give a "seed" of 
$10,000 to the company in line 1004 
to start off the generation of the 20 
years of planning and bookings. Each 
month's plan is based on the past 
month's bookings within the limits 
established by line 1110. This gives a 
probability of a 6 percent decrease or 
a 14 percent increase in next month's 
plan. The bookings for a month are 
based on the plan for the current 
month. As shown in line 1210, the 
probability of increased bookings is 
15 percent and 5 percent probability 
for decreased bookings. This process 
ends in one of two ways. If you suc- 
cessfully generate 20 years of data, 
then you return. If you try to divide 



5 

-I 

§ 




v . k.li La j 



TIME 



Fig. 2b. Z-chart for a 5 percent per month 
growth company. 



< 




TIME 



Fig. 2d. Z-chart for an unplanned withdrawal. 



THE Z-CHART FOR 1974 



450 h 
427 k 
405 h 
562 k 
560 k 
557 k 
515 k 
292 k 
270 k 
247 k 
225 k 
202 k 
180 k 
157 
155 
112 



90 
67 
45 
22 




k 
k 
k 
k 
k 
k 
k 
k 



B 



$ $ 



B 



m 



B 

m 



B 

m 



B 



m 



B 



m 



j_ 



m 



m 



m 



_i_ 



m 



m 



m 



YEAR-* 1974 



5 6 

MONTH 



10 



II 



12 



Fig. 3. Z-chart for a very good year. 




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Microcomputing, December 1981 149 



by zero, then you call the error trap- 
ping and report that the company 
went bankrupt. During this process 
you will also be filling your data ar- 
ray, S( 120,3). 

PLOT Z-CHART-2000. This is the 
most difficult part of the program and 
the section that may deserve special 
attention, if you find that fooling 
around with arrays is a fun way to 
spend a couple of hours. 

After verifying that a proper year 
has been selected (2000-2023), you 
back up 1 1 months and get the sum of 
the bookings during that period 
(2028-2038). The code from 2040 to 
2070 is a major FOR-NEXT loop that 
sets the proper data from array S(X,3) 
and makes the necessary additions 
and subtractions to the array G(4,N). 

To do the automatic scaling of the 
y-axis, the maximum value is deter- 
mined in lines 2066 to 2068. After ar- 
ray G(4,N) has been filled, you call 
routine 2100, which does the auto- 
matic scaling of the y-axis based on 
the size of R in the array Z(R,C). This 
is done in lines 2106 to 2114. The 
assignment of the value for Z(R,C) is 
done in line 2140. Note that this is 
third-level nesting— for each unit of 



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150 Microcomputing, December 1981 



the y-axis, for each month and for 
each of the four possible values in 
G(4,N). 

Finally, the call is made to rou- 
tine 2200, which does the printing 
of the Z-chart. 



Figs. 3 and 4 show sample runs for 
the years 1974 and 1978 using the 
data from Table 2. The symbol B rep- 
resents the YTD bookings, and P is 
the YTD plan. A lowercase m repre- 
sents the monthly planned bookings, 



THE Z-CHART FOR 1978 



516 

495 

474 

454 

433 

412 

392 

371 

350 

330 

309 

288 

268 

247 

227 

206 

185 

165 

144 

123 

103 

82 

61 

41 

20 





$ 

P 



P 
$ 



$ 

B 



m 
B 
i 



m 



B 
m 



P 

B 

m 



B 



m 



m 



m 



m 



m 



m 



m 



m 



-i i_ 



YEAR-* 1978 



5 6 7 

MONTH 



10 



II 



12 



Fig. 4. Z-chart for a very bad year. 



Variable Description 

CI Number of items in main menu 

F Used as scaling factor 

Fl Flag used during display of main menu 

G(4 12) Temporary storage array 

M Local variable usually represents the month 

M$ Title of this program 

Q Output port for listing and displays 

Ql Selecting from the main menu 

Rl Vertical resolution of y-axis of z-chart 

S(240 3) Array of time-plan-bookings 

S$ Subtitle for main menu 

Y 1 First year of data 

Y2 Last year of data 

Z)R1 12) Array for plotting the z-chart 

Z$ File name of stored data 

Table 1. Major variables used in ZCHART.BAS. 



Year 



Months 



1 



IMIIIItltll 



lllttllllllll 



Entire data File 
PLAN/BOOKINGS 

::::::ti::::i::::::: 



HIIIIIIIIIIIIIHIIItl 



10 



11 



12 



I:::::::::::::::::::::::::::::::::::::::::::::::: 












71 
72 
73 
74 
75 
7b 
7/ 
78 
79 
80 
81 
8? 
83 
84 
85 
86 
87 
88 
89 
90 



15/15 

15/15 

16/16 

26/28 

46/48 

27/27 

16/32 

32/16 

28/25 

32/48 

46/47 

52/52 

71/75 

83/88 

123/129 

157/157 

231/220 

29/30 

40/50 

64/64 

::x:::::i::: 



15/15 

15/15 

17/17 

30/30 

46/46 

26/26 

16/32 

34/18 

26/30 

44/56 

45/46 

50/56 

71/77 

91/97 

119/121 

176/187 

248/254 

32/34 

46/51 

67/75 

::::i:z::: 



15/15 

15/15 

17/17 

31/31 

44/44 

24/24 

16/32 

36/18 

25/28 

70/52 

45/49 

54/61 

73/81 

100/113 

129/144 

189/205 

239/273 

36/36 

45/46 

75/80 



15/15 

15/15 

18/18 

33/33 

42/42 

23/23 

16/32 

38/19 

32/30 

38/28 

42/42 

56/59 

82/88 

97/96 

141/137 

198/211 

267/268 

38/40 

50/51 

85/94 



15/15 

15/15 

19/19 

34/34 

40/40 

22/22 

16/32 

40/20 

33/35 

50/34 

47/54 

58/58 

80/81 

101/100 

136/130 

220/213 

258/245 

41/44 

51/49 

85/91 



15/15 

15/15 

20/20 

36/36 

38/38 

21/21 

16/32 

42/20 

31/29 

78/51 

45/51 

61/61 

84/88 

113/110 

155/152 

225/235 

279/310 

39/39 

52/52 

92/89 



15/15 

15/15 

21/21 

38/38 

36/36 

20/20 

16/32 

44/21 

35/33 

43/41 

46/46 

66/71 

86/92 

110/111 

154/160 

255/289 

292/296 

43/46 

55/61 

93/104 



15/15 


15/15 


15/15 


15/15 


15/15 


15/15 


15/15 


15/15 


15/15 


15/15 


22/22 


23/23 


24/24 


26/26 


27/27 


40/40 


42/42 


44/44 


46/46 


48/48 


34/34 


33/33 


31/31 


30/30 


28/28 


19/19 


18/18 


17/17 


17/17 


16/16 


16/32 


16/32 


16/32 


16/32 


16/32 


46/Z1 


48/22 


50/22 


52/23 


54/24 


34/39 


36/25 


35/20 


35/25 


30/25 


56/5 


87/87 


41/41 


54/54 


82/82 


47/46 


49/54 


51/48 


51/48 


51/50 


67/68 


73/71 


83/94 


89/92 


93/93 


80/85 


80/83 


81/78 


77/84 


74/84 


115/116 


124/133 


117/122 


132/139 


133/147 


166/178 


159/161 


166/162 


165/162 


169/167 


261/276 


270/304 


264/284 


261/298 


284/277 


304/299 


304/318 


286/307 


275/309 


263/284 


45/50 


50/53 


50/57 


45/50 


50/60 


53/61 


56/62 


57/57 


60/60 


67/76 


102/98 


110/118 


110/117 


118/119 


115/124 






:::>i:i:::::::::s:ti 



::::::::::: 



::::::::::::::::::::: 



Table 2. Twenty years of data. 



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TRS80 MODEL 1 LEVEL II COMPATIBLE 


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PRINTER PORT 


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REVERSE VIDEO 


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Microcomputing, December 1981 151 



while $ is the sum of the last 12 
months of bookings. Since the ab- 
solute variation in the monthly plan 
is generally small compared to the 
maximum value of the y-axis, the 
slope of the bottom bar of the Z may 
not always be apparent from the 
chart. In this case, you should check 
the values used to plot the chart. 

SAVE DATA— 3000. This section 
saves the array S(X,3) in a data file 
named Z$. First, it tests to see if the 
file exists (line 3010). If it does, it 
jumps to line 3020 and writes on top 
of existing data. If the file, Z$, does 
not exist, then it is created in line 
3012. The element S(X,1) of each 
record is a composite number, with 
the first two digits equal to the year 
and the remaining digits equal to the 
month. The element S(X,2) repre- 
sents the planned bookings and the 
last element stands for the bookings. 

LIST TWENTY YEARS— 4000. A 
complete printout of all 20 years of 
data may be obtained by calling this 
routine. If you display the data on 
your terminal, Q=l, then a slight 
pause follows each year's display, 
using the WAIT = 3 statement in 
line 4040. 

GET DATA FROM DISK— 5000. 
This is the inverse of section 3000. 
You may need to rewrite for your 
particular system. 

LIST ONE YEAR— 6000. You are 
first prompted for the year to be dis- 
played; a linear search is then made 
to find the first month of the year. If 
the search fails, then you report it 
and ask if another year is wanted. 
When the year is found, you deter- 
mine where to print the data by call- 
ing routine 8000 to assign the port 
number, Q. The heading is printed 
via routine 8100. The data for the 
year is printed by routine 6100, 
which also makes a calculation of the 
ratio of bookings to plan. 

CHANGE DATA— 7000. If you 
want to change the data for a year, 
this section is called. You again find 
the year under consideration, and 
then for 12 months display the cur- 
rent plan and bookings. This permits 
you to change the data. The array 
S(X,3) is changed during the process. 
If you use this section you should re- 
member to save the data in the file Z$. 

Listing 2, ZLIST.BAS, is not a nec- 
essary part of the overall concept of 
Z-charting, but will prove useful as 
you generate your own data. The pur- 
pose of this program is to display a 
compact form of the 20 years of data 
contained in array S(N,3). Table 2 

15 2 Microcomputing, December 1981 



was printed using this program. 

Future 

You can improve this program in 
several ways. If you select a large 
value for the y-axis resolution, you 
may find that the time required to fill 
the array is excessive and will want 
to find a way to speed up this process. 

The bottom-bar problem men- 
tioned earlier might be solved using 
some sort of a software logarithmic 
amplifier, but I have no ideal way to 
use and merge it into this program. 

This program restricts the Z-chart 
plotting from January to December. 
You might want to expand the pro- 



gram so that any month could be the 
starting month, since many compa- 
nies start their fiscal year in July 
or September. 

Conclusion 

A friend introduced me to Z-chart- 
ing about nine months ago. It has tak- 
en me that long to begin to under- 
stand the concept and work out the 
program. Z-charting may help the 
businessman to get a little better view 
of his business. For the programmer, 
I hope you have gained some insight 
into another technique of making a 
scaled data array from the raw data of 
another array. ■ 



0001 

0002 

0003 

0004 

0010 

0020 

0099 

0100 

0101 

0110 

0112 

0120 

0122 

0124 

0128 

0130 

0132 

0134 

0136 

0138 

0140 

0170 

0180 

0190 

0192 

0194 

0198 

0199 

0900 

0901 

0910 

0920 

0990 

0999 

1000 

1001 

1004 

100G 

1010 

1014 

1020 

1022 

1024 

1026 

1042 

1048 

1050 

1056 

1058 

1060 

1062 

1072 

1074 

1076 

1078 

1080 

1082 

1084 

1086 



Listing 1. ZCHART.BAS. 



I ZCHART.BAS 

■ 

I Gene Embry 

■ 
■ 

ON ERROR GOTO 9990 

G09UB 9800:: Prosram initialization 

: Main 

• 

HOME 

LET DIGIT9«0:RJU5T=0 

PRINT TAB(W-LEN(M*)/2) JMfrPRINT 

PRINT TAB<W-LEN<S*>/2> JS$:PRINT 

PRINT "Y-axis resolution * ■JH1 ?"units. M 

PRINT 

FOR X=l TO CI 

let x**str*(x)+ m . m 

if imod<x,2>*o print tab<w>?:fi=i 

print x*;n$<x> ; 

IF Fl = l THEN PRINTIF1«0 

NEXT X 

5KIP 2 

INPUT "Make selection ",G1 

IF Ql < 1 THEN 100 

IF 01 > CI THEN 900 

GOSUB N(G1) 

GOTO 100 

: Done 

• 

PRINT 

PRINT M Bye! M 

END 

a 

I Make data 



Ne provide 'seed-money' of $10r000 



let p*io:n=o:: 

GOSUB 8000 : TPort 

FOR Y = Y1 TO Y2:: Years 

GOSUB 8100:: Print heading 

FOR M*l TO 12:: For 12 months 

GOSUB UOOriGet this month's plan 

GOSUB 1200::Get this month's bookings 

GOSUB 1300::Fill up the array 

PRINT #Q,M, 

DIGITS* 1 

PRINT #Q,PrS. (S/P>*100: : Ratio of monthly bookings to plan 

DIGITS* O 

NEXT M 

DIGITS* 1 

LET Vl*< (S1-P1)/P1)»100: :Ratio of annual bookings to Plan 

LET U** M *=" : GOSUB 8200 

PRINT #Gr"Totals M rPlrSlrYl 

DIGITS* 

let p=si/i2:pi*o:si*o 

PRINT #Q 

IF Y>=Y2 THEN 1088 
IF G=l WAIT 5 
NEXT Y 




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Microcomputing, December 1981 153 



Listing continued. 



1088 

1090 

1099 

1100 

1101 

1110 

1120 

1130 

1140 

1190 

1199 

1200 

1201 

1210 

1220 

1230 

1240 

1290 

1299 

1300 

1301 

1310 

1320 

1322 

1330 

1332 

1^34 

1390 

1399 

2000 

2001 

2008 

2010 

2012 

2014 

2016 

?oi8 

2020 



RJUST* 0:diaits=0 
RETURN 

: Get this month's Flan 

■ 

LET L*INT(P».94) :H«INT(P»1.14) I I 8ee text 

LET P«( (H-L+l >»RND+L> I I This month's plan 

LET P«INT(P) 

LET P1=P1+P: ITotal of this years planned bookings 

RETURN 

■ 

: Get this month's Bookings 

a 

• 

LET L«INT<P*.95) :H=INT(1.15«P) 

LET S=( (H-L+l >*RND+L> : : This month's bookinas 

LET S=INT(S) 

LET S1*SH-S: TThis year's bookinas 

RETURN 

• 
■ 

I Fill array S<240,3> 

• 

LET N=N+1 

LET Tf> = 8TR*(Y)+8TR*<M> 

LET T*VAL(T$> 

LET S(Nr 1)=T: lYear and month 

LET S(Nf2)=P: :Plan for this month 

LET S(Nr3) =S: IBookinas for this month 

RETURN 

: Plot the z-chart 

a 

• 

INPUT "Plot the z-chart for which year %T 

IF T < Yl+1 PRINT "Year must be areater than H ?Y1 

GOSUB 8000 I '.port 

LET X»=STR»<T)+ M 1": IFind Jan.'s data for year, T 

FOR Y = 1 TO 240 8TEP 12 

LET T*=8TR*<8<Yrl> ) 

IF X**T* THEN 2028:: Me found it 



GOTO 2000 




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1S4 Microcomputing, December 1981 



Listing continued. ?022 

2024 



?028 

2030 

2032 

2034 

2036 

2038 

2040 

2046 

2048 

2050 

2052 

2054 

2056 

2058 

2060 

2062 

2<>64 

2<>66 

2067 

2068 

2070 

2076 

2078 

2080 

2082 

2086 

2088 

2080 

2089 

2100 

2101 

2105 

2106 

2110 

2112 

2114 

2120 

2122 

2130 

2140 

2150 

2160 

2170 

2190 

2199 

2200 

2>:oi 

2206 
2208 
2209 
2210 
2V12 
2214 
2218 
2220 
2222 
2230 
2232 
2234 
2236 
2238 
2240 
2242 
2250 
2280 
2282 
2284 

— - • 

2288 
2289 
2^90 
2299 
3000 
3001 
3010 
3012 
3014 
3020 
3022 
3O30 
3032 
3040 



NEXT Y 

PRINT "Not on file":GOTO 

PRINT "Working" 

let y3=y-u:h=o:s=o:n=o: 
for x = 1 to 12 !for z = 

Y3 TO Y-l 

S + S(Xr3) 



2080: IFailed to find the year 



Y3 holds the position of 11 

2 to 3:c(ZrX>=o:NEXT z:next 



months 
X 



ago 



FOR X = 
LET 5 = 
NEXT X 



ISum of last 11 months bookings 



X = Y TO Y+ll 

S = S + S(Xr3)i:Add this months' bookings 
N ■ N ♦ 1 : : M o v e to next months pointer 
G(lrN) = s::Keeps sum of 12 months of bookings 
G(2rN) = G(2rN) + 8(Xr2)::YTD total of years plan 
N>1 THEN G(2,N> = G ( 2 , N ) +G< 2 r N-l ) : : YTD total of bookings 



G(3rN) ■ 
G(4rN) = 



G(3rN) 

S ( X , 2 ) 



♦ 8<X,3> : :YTD bookings 
TPlan for this month 



G(3rN) = G<3rN)+G<3,N-l > 



S<Y3,3) : :Subtract 



+ 
H 
H 
H 



1 I : mo ve to next 



11th month old booking 
months bookings 



FOR 

LET 

LET 

LET 

LET 

IF 

LET 

LET 

IF N>1 THEN 

LET S = S - 

LET Y3 = Y3 

IF G(lrN) > 

IF G<2,N> > 

IF G(3rN) > 

NEXT X 

G08UB 2100: IF ill Z( ) 

G08UB 2200::print the 

IF Q <> 1 THEN PRINT 

INPUT "Z-chart another year 

IF G$ = " y M THEN G*="Y" 

IF Q* = "Y" THEN 2000 

RETURN 



Fill up Z(R1,12) based on values in G<4,12) 



THEN H 
THEN H 
THEN H 



= G(1,N) 

= G<2,N) 

= G(3,N) 



:f ind 
If ind 
."find 



the 
the 
the 



max 
max 
max 



value 
v a 1 u e 
value 



with proper 
array 



"rQ$ 



ual ues 



r 



"Filling the array! 

= H/Rl I :8caling factor 

= 1 TO RKIFor each unit 

R? 

= H-( (R-1)»F> :Z2 = <H-(R»F>> 
= 1 TO 12i: For each month 
RrC) = O.'.'Assume a space will 
= 1 TO 4:: Assign the type of 
rC) <= Zl IF G(X,C> > Z2 THEN 



on the y-axis 

determines upper & 



be printed. See 
inf omat ion 

Z(RrC) = X 



lower limits 
line #2230 



PRINT 
LET F 
FOR R 
PRINT 
LET Zl 
FOR C 
LET Z( 
FOR X 
IF G(X 
NEXT X 
NEXT C 
NEXT R 
RETURN 



: Print the array after filling it 

■ 

PRINT #Q 

PRINT #G, TABOO) ?"THE Z-CHART FOR "', I T*»" 19"+STR*< T) : PRINT #G,T* 

PRINT #G 

FOR R = 1 TO Rl 

LET Zl=H-< <R-1)»F) : ."Scaled value for vertical axis 

PRINT #QrINT(Zl) ? 

PRINT #G,TAB<06) ?"k I "J 

FOR C = 1 TO 12 

PRINT #QrTAB(P08-»-4) ; : Position the printing head 



THEN PRINT #Q," " ; 

THEN PRINT #Q , "*"?:: Sum of last 12 months bookings 

THEN PRINT #G,"P"?::Sum of PLAN - YTD 

THEN PRINT #Gr"B";::Sum of bookings - YTD 

THEN PRINT #Q, "m" ' ." I Mon t hi y Plan for this year 



IF Z(RrC) ■ 

IF Z<R,C) = 1 

IF Z(R,C) = 2 

IF Z(RrC) = 3 

IF Z(R.C) = 4 

NEXT C 

PRINT #Q 

NEXT R 

PRINT #G, "0" ? TAB (06) ? "k I"? 

FOR X = 1 TO 35:PRINT #Q , "__" ? ."NEXT X:PRINT #Q 

FOR X = 1 TO 12 

°RINT #G,TAB(X*5+10) JX? 

NEXT X: PRINT #Q 

PRINT #Q,"Year -> " ? T$ ?TAB( 38 ) ? "Mon t h" 

RETURN 

: Save data 

■ 

IF FCHK Z$<>5 THEN 3020::if Z* exists then skip to #3020 

CREATE #10,Z*r240r36: : Otherwise create the file Z* 

CLOSE #10 

OPEN #10, Z$ 

RECNO #10=1 

FOR X=l TO 240 

IF S(Xrl)=0 THEN 3080 

WRITE #10,S(X, 1) ,S(X,2) ,S(X,3) 




More 






Microcomputing, December 1981 1 55 



Best prices 
anywhere 

We beat 'em all ! 



COMPUTERS 
North Star 

Horizon 2-48K DD List $3945. . . CALL 
Horizon 2-64K DD, List $4195. . . CALL 
Horizon 2-64K QD, List $4495. . . CALL 
Advantage 2Q-64K, List $3999 . . CALL 

Intersystem DP-2A, List $1749 . . CALL 

Cromemco Z 2H. List $9995 $7945 

System 2. 64K List $4695 $3549 

System 3, 64K List $7995 $6349 

Intertec SuperBrain SPECIALS 



S\ 



64K Ram, List $3495 $2595 

64K Quad, List $3995 $2995 

Disk Systems 

Thinker Toys, Discus 2D $ 849 

Dual Discus 2D $1389 

D-scus2 t2 $1199 

M 26 $3599 

M 10 $2995 

Printers & Terminals 

Paper Tiger IDS-445G $ 739 

460G $ 839 

Centronics 730-1, List $795 . . .$ 549 
739-1, List $995 . . .$ 749 

704-9 Ser $1519 

704-11 parallel $1569 

TI810, List $1649 $1289 

Nee Spinwriter 7730 $2395 

7715 $2395 

7710 $2395 

Diablo 630, List $2711 $2049 

Intertube III, List $895 $ 725 

Zenith Z-19 $ 719 

Televideo910C $ 579 

912C $ 659 

920C $ 729 

950C $ 945 

Hazeltine Espirit $ 589 

1420 $ 789 

1500 $ 845 

Soroc IQ120, List $995 $ 689 

IQ130 $ 579 

IQ135 $ 719 

IQ140 $ 995 



Computers 
Wholesale 

P.O. Box 144Camillus, N.Y. 13031 

Our order line is 

«m (800) 448-5715 

For other information call: 

(315)472-2582 

Most items in stock for immediate delivery Fattory sealed cartons, 
w/full factory warranty NYS residents add appropriate sales tax 
Prices do not include shipping. VISA and Master Charge add 3% 
COD orders require 25% deposit Prices subject to change without 
notice 









Listing continued. 

3060 NEXT 

3080 

3090 

3093 

4000 

4001 

4010 

4020 

4022 

4030 

4040 

4080 

4082 

4 088 

4090 

4099 

5000 

5001 

5010 

5012 

5020 

5030 

5040 

5050 

5080 

5090 

5099 

6000 

6001 

6006 

6008 

6010 

6011 

6012 

6014 

6016 

6018 

6019 

6020 

6028 

6030 

6040 

6080 

6082 

6084 

6086 

6090 

6099 

6100 

6101 

6140 

6142 

6144 

6146 

6148 

6150 

6152 

6160 

6170 

6172 

6174 

6180 

6190 

6199 

7000 

7001 

7010 

7020 

7022 

7024 

7030 

7032 

7034 

7040 

7080 

7082 

7O90 

7098 

8000 

8001 : 

8010 INPUT 

8012 IF Q 

8020 IF G=l 

8090 RETURN 



X 
CLOSE #10 
RETURN 

I Print the complete array 



Which port 



GOSUB 8000 

LET Y=l 

GOSUB 8100! : print 

GOSUB BlOO: : print 

IF Q = 1 THEN WAIT 

LET Y ■ Y ♦ 12 

IF Y < 241 THEN 4022 

rjust=: o:digits=o 

RETURN 

■ 
■ 

: Get data from disK 



h e a d i n a 
this years 
3 



data 



If can't open the line #3990 is called!! 



OPEN #10rZ«: 

RECNO #10=1 

FOR X=l TO 240 

READ #10,S<X,1 ) ,S(X,2) ,S<X,3) 

IF S(Xr 1 )*0 THEN 5080 

NEXT X 

CLOSE #10 

RETURN 

• 

: Print a sinale years data 
PRINT 

let pi«o:si«o:vi*o 

INPUT "Which years' data "-T 

LET X*=STR*<T>+" 1" 

FOR Y = 1 TO 240 STEP 12 

LET T*=STR*(S(Yr 1 ) ) 

IF X* = T* THEN 6020 

NEXT Y 



PRINT 

IF Ql 

GOSUB 

GOSUB 

GOSUB 

PRINT 

INPUT 

IF Q* 

IF G* = 

RETURN 



"NOT 
= 7 
8000 
8100 
6100 



ON FILE " I GOTO 6080 
THEN RETURN 
! port? 
IHEADING 



"Want another years 
THEN Q*="Y" 
THEN 6000 



data ( Y or N ) 



G* 



• I y II 

V" 



I Scan and print one year 

• 

FOR X = Y TO Y+ll 

PRINT #G,X-Y-U r 

LET Z=S<X,3)/S(X,2>*100 

LET Pl=Pl+S(Xr2) :Sl=Sl+S(Xr3) 

DIGITS= KRJUST = 3 

PRINT #G,S<Xr2) ,S<X,3) ,Z 

DIGITS' OIRJUST = 

NEXT X 

LET u$="== m :gosub 
RJUST= 2:digits=i 

PRINT #G, "Totals" 
DIGITS' OIRJUST = 
RETURN 



8200 1 I under 1 in e* 



PI 




SlrSl/PlMOO 



Insert other data 



GOSUB 

HOME 

PRINT 

PRINT 

FOR X 

PRINT 

INPUT 

NEXT X 

INPUT 

IF G* = 

RETURN 

: Port 



6000IIGet position in the array 



"Year -> "?T 
"Month" r "Old 
= Y TO Y+ll 
X-Y+1,S<X,2> 



Plan","01d Bookinas 



S ( X , 3 ) 



"New Plan, BooKinas " , S( X , 2 ) t S ( X , 3) 



Want to chanae 
"Y" THEN 7000 



another years' data (Y/N) 



G* 



"Which port 
O 3 THEN G = 



IF QlOl 



1 
THEN 



HOME 




More 



156 Microcomputing, December 1981 



NEW! TPM* for TRS-80 Model II 
NEW! System/6 Package 

Computer Design Labs 



Z80 Disk software 



We have acquired the rights to all TDL software (& hardware). TDL software has long had the reputation of being the best in the 

industry. Computer Design Labs will continue to maintain, evolve and add to this superior line of quality software. 

— Carl Gal left i and Roger Amidon, owners. 
Software with Manual/Manual Alone 



All of the software below is available on any of the 
following media for operation with a ZOO CPU using 
the CP/M* or similar type disk operating system 
(such as our own TPM*). 

for TRS-80* CP/M (Modal I or II) 
for 8" CP/M (soft sectored single density) 
for S'A" CP/M (soft sectored single density) 
for 5 1 /4" North Star CP/M (single density) 
for 5 1 /4" North Star CP/M (double density) 

BASIC I 

A powerful and fast Z80 Basic interpreter with EDIT, 
RENUMBER, TRACE, PRINT USING, assembly language 
subroutine CALL, LOADGO for "chaining*, COPY to 
move text, EXCHANGE, KILL, LINE INPUT, error inter- 
cept, sequential file handling in both ASCII and binary 
formats, and much, much more. It runs in a little over 1 2 
K. An excellent choice for games since the precision 
was limited to 7 digits in order to make it one of the 
fastest around. $49.95/$15. 

BASIC II 

Basic I but with 1 2 digit precision to make He power 
available to the business world with only a slight sacrifice 
in speed. Still runs faster than most other Basics (even 
those with much less precision). $99. 95/$ 15. 

BUSINESS BASIC 

The most powerful Basic for business applications, it 
adds to Basic II with random or sequential disk files in 
either fixed or variable record lengths, simultaneous 
access to multiple disk files, PRIVACY command to 
prohibit user access to source code, global editing, 
added math functions, and disk file maintenance capa- 
bility without leaving Basic (list, rename, or delete). 
$179.95/$25. 

ZEDIT 

A character oriented text editor with 26 commands 
and "macro" capability for stringing multiple commands 
together. Included are a complete array of character 
move, add, delete, and display function. $49. 95./$ 1 5. 

ZTEL 

Z80 Text Editing Language - Not just a text editor. 
Actually a language which allows you to edit text and 
also write, save, and recall programs which manipulate 
text. Commands include conditional branching, subrou- 
tine calls, iteration, block move, expression evaluation, 
and much more. Contains 36 value registers and 1 text 
registers. Be creative! Manipulate text with commands 
you write using Ztel. $79.95/$25. 

TOP 

A Z80 Text Output Processor which will do text 
formatting for manuals, documents, and other word 
processing jobs. Works with any text editor. Does 
justification, page numbering and headings, spacing, 
centering, and much more! $79.95/$25. 

MACRO I 

A macro assembler which will generate relocateable 
or absolute code for the 8080 or Z80 using standard 
Intel mnemonics plus TDL/Z80 extensions. Functions 
include 14 conditionals, 16 listing controls, 54 pseudo- 
ops, 1 1 arithmetic/logical operations, local and global 
symbols, chaining files, linking capability with optional 
linker, and recursive/ reiterative macros. This assembler 
is so powerful you'll think it is doing all the work for you. It 
actually makes assembly language programming much 
less of an effort and more creative. $79.95/$20. 

MACRO II 

Expands upon Macro I's linking capability (which is 
useful but somewhat limited) thereby being able to take 
full advantage of the optional Linker. Also a time and 
date function has been added and the listing capability 
improved. $99.95/$25. 

LINKER 

How many times have you written the same subroutine 
in each new program? Top notch professional pro- 
grammers compile a library of these subroutines and 
use a Linker to tie them together at assembly time. 
Development time is thus drastically reduced and 
becomes comparable to writing in a high level language 
but with all the speed of assembly language. So, get the 
new CDL Linker and start writing programs in a fraction 
of the time it took before. Linker is compatible with 
Macro I & II as well as TDL/Xitan assemblers version 2.0 
or later. $79.95/$20. 



DEBUG I 

Many programmers give up on writing in assembly 
language even though they know their programs would 
be faster and more powerful. To them assembly language 
seems difficult to understand and follow, as well as 
being a nightmare to debug. Well, not with proper tools 
like Debug I. With Debug I you can easily follow the flow 
of any Z80 or 8080 program. Trace the program one 
step at a time or 1 steps or whatever you like. At each 
step you will be able to see the instruction executed and 
what it did. If desired, modifications can then be made 
before continuing. It's all under your control. You can 
even skip displaying a subroutine call and up to seven 
breakpoints can be set during execution. Use of Debug I 
can payforitself many timesover by saving you valuable 
debugging time. $79 95/$20. 

DEBUG II 

This is an expanded debugger which has all of the 
features of Debug I plus many more. You can "trap" (i.e. 
trace a program until a set of register, flag, and/or 
memory conditions occur). Also, instructions may be 
entered and executed immediately. This makes it easy 
to learn new instructions by examining registers/memory 
before and after. And a RADIX function allows changing 
between ASCII, binary, decimal, hex, octal, signed 
decimal, or split octal. All these features and more add 
up to give you a very powerful development tool. Both 
Debug I and II must run on a Z80 but will debug both Z80 
and 8080 code. $99.95/$20. 

ZAPPLE 

A Z80 executive and debug monitor. Capable of 
search, ASCII put and display, read and write to I/O 
ports, hex math, breakpoint, execute, move, fill, display, 
read and write in Intel or binary format tape, and more! 
on disk 

APPLE 

8080 version of Zapple 



SYSTEM/6 

TPM with utilities, Basic I interpreter, Basic E compiler, 
Macro I assembler, Debug I debugger, and ZEDIT text 
editor. 

Above purchased separately costs $339.75 
Special introductory offer Only $1 79.75 with coupon!! 




I 



*' 
+?<*' 



<> s 






NEW! TPM no 
II! 



TPM* 



r TRS-80 Model 



A NEW Z80 disk operation system! This is not CP/M*. 
If s betted You can still run any program which runs with 
CP/M* but unlike CP/M* this operating system was 
written specifically for the Z80* and takesfull advantage 
of its extra powerful instruction set. In other wprds its 
not warmed over 8080 code! Available for TRS-80* 
(Model I or II). Tarbell, Xitan DDDC, SD Sales "VERSA- 
FLOPPY", North Star (SD&DD), and Digital (Micro) 
Systems. $79.95/$25. 



•<* $1 60. 



.00 | 



ORDERING INFORMATION 

Visa, Master Charge and C.O.D. O.K. To order call or 
write with the following information, f^^^m 

1. Name of Product (e.g. Macro I) 

Media (e.g. 8" CP/M) WBBl 3 

Price and method of payment (e.g. C.O.D.) include 

credit card info, if applicable. 

Name, Address and Phone number. 

For TPM orders only: I ndicate if for TRS 80, Tarbell, 

Xitan DDDC, SD Sales (6V or 8"). ICOM (6W or 

8"), North Star (single or double density) or Digital 

(Micro) Systems. 

N.J. residents add 5% sales tax. 




2. 
3. 

4. 
5. 




Manual cost applicable against price of subsequent 
software purchase in any item except for the Osborne 
software. 



SYSTEM MONITOR BOARD (SMBII) 

Acomplete I/O board for S-1 00 systems. 2 serial ports, 
2 parallel ports, 1200/2400 baud cassette tape inter- 
face, sockets for 2K of RAM, 3-2708/27 1 6 EPROM's or 
ROM, jump on reset circuitry. Bare board $49.95/520. 609"599"2 1 46 



For information and toch quorios call 



ROM FOR SMB II 

2KX8 masked ROM of Zapple monitor. Includes source 
listing $34.95/$ 1 5. 

PAYROLL (source code only) 

The Osborne package. Requires C Basic 2. 
5" disks $124.95 (manual not included) 
8" disks $ 99.95 (manual not included) 
Manual $20.00 

ACCOUNTS PAYABLE/RECEIVABLE 
(source code only) 

By Osborne, Requires C Basic 2 
5" disks $1 24.95 (manual not included) 
8" $99.95 (manual not included) 
Manual $20.00 

GENERAL LEDGER (source code only) 

By Osborne. Requires C Basic 2 
5" disks $99.95 (manual not included) 
8" disks $99.95 (manual not included) 
Manual $20.00 



C BASIC 2 

Required for Osborne software. $99.95/$20. 



For phone orders ONLY call toll free 

1 -800-327-91 91 
Ext. 676 

(Except Florida) 

OEMS 

Many CDL products are available for licensing to 
OEMs. Write to Carl Galletti with your requirements. 

* Z80 is a trademark of Zilog 

* TRS-80 is a trademark for Radio Shack 

* TPM is a trademark of Computer Design Labs. It is not 
CP/M* 

* CP/M is a trademark of Digital Research 

Prices and specifications subject to change without 
notice. 

DEALER INQUIRIES INVITED. 




COMPUTER 

DESIGN 

LABS 



«^18 



342 Columbus Avenue 
Trenton, N.J. 08629 



^See List of Advertisers on page 210 



Microcomputing, December 1981 157 



■ riff < t . m oiiij • imj u in* ■ ^iiiiiii.n 

MICfl C8YSI LMS 



39 E. Hanover Ave., Morris Plains, NJ 07950 

Finally, there's a magazine with up- 
to-date, informative articles for the 
serious microcomputer user! MICRO- 
SYSTEMS focuses on CP/M, Pascal, 
and related software, on North Star 
and S-100 bus hardware (including 16- 
bit systems). You'll find applications, 
tutorials, hardware and software 
reviews, and a software directory. Keep 
up on the latest developments in the 
S-100 and CP/M world with MICRO- 
SYSTEMS! 

□ Sign me up! 

□ Send a sample copy! ($2 enclosed) 

□ Send more information. 



KBLH 



Name 



Address 



City 

State/Zip 



Term USA 

1 YR( 6 issues) □ $10 

2 YR (12 issues) □ $18 

3 YR (18 issues) D $24 

□ Payment enclosed □ 

□ VISA □ MasterCard □ 

Card Number : 



Canada, 
Mexico 

□ $15 

□ $27 

□ $38 



Foreign 
(Air) 
D $25 
□ $48 
D $69 



Bill me ($1 Charge) 
American Express 

Exp. Date : 



Signature : 



IF 
IF 
IF 
IF 
LET 



Listing continued 
8099 
8100 
8101 
8110 
8142 
8144 
8145 
8146 
8148 
8150 
8160 
8170 
8180 
8182 
8190 
8199 
8200 
8201 
8220 
8230 
8240 
8280 
8290 
8299 
9800 
9801 
9808 
9810 
9811 
9812 
9814 
9816 
9820 
9822 
9324 
9830 
9832 
9834 



Print Headina 



Q=l THEN HOME 
Y>240 THEN Y=l 
Y=0 THEN Y=l 
Ql=3 THEN T=Y:G0T0 
T*=STR*(S(Y,1) ) 



8150: Iwakina new data 



LET T=VAL(LEFT*<T*,2) ) 

PRINT #Qr "YEAR = '" ? T 

PRINT #Qr ,"Plan"r H Bookins5"r"Bookinas/Plan" 

PRINT #Qr"Month M »"(k dollars)"»"(K dollars)", M ( 7. > " 

LET U* = " — " ". GOSUB 8200 

LET P1=0IS1=0:V1=0: IReset 

RETURN 

: Print underline 

• 

FOR K=l TO 30 
PRINT #G,U*? 
NEXT K 
PRINT #Q 
RETURN 



Psrri. Variables 



rRl 



INPUT "Specify the y-axis resolution 
DIM S(240»3) : IData Array 

Z(R1 t 12) : IThe z-chart array 

G(4r 12) I ITewporary storage array 

W=30:LINE=0 

Yl=7i:Y2=90: I from 1971 

Z*="ZCHART.DAT M 

M*= M Z-Chartin3 a business" 

St«"Data from 19"+STR*< Yl )+" to 19"+STR$< Y2) 

X = 1 TO 8 
N$(X) ,N<X) 



DIM 
DIM 
LET 
LET 
LET 
LET 
LET 
FOR 
READ 



to 1990 



LET Cl=Cl+i:: Counter For items in Menu 




More 



Z8 BASIC 
COMPUTER/CONTROLLER 




As featured in 
Byte Magazine, July and August 1981 

• On board tiny BASIC Interpreter. 

• 2 on board parallel ports. 

• Serial I/O port 

• 6 interrupts. 

• Just attach a CRT terminal and 
immediately write control programs 
in BASIC. 

•BAUD RATES 110-9600 BPS. 

• Data and address buses available for 
124K memory and I/O expansion. 

• 4K RAM, 2716 or 2732 EPROM 
operation. 

•Consumes only 1 Vi WATTS 
Z8 Basic Microcomputer/Controller 

Assembled & Tested $195.00 

Complete Kit $165.00 

Universal Power Supply 

( + 5, + 12, &-12v) $ 35.00 

Z8 is a trademark of Zilog Inc. 



SWEET-TALKER, 

IT GIVES YOUR COMPUTER 

AN UNLIMITED VOCABULARY. 




As Featured In 
Byte Magazine, September 1981 

•Utilizes VORTRAX SC-01 A speech 
synthesizer chip. 

• Unlimited vocabulary. 
•Contains 64 different phonemes 

which are accessed by an 8-bit code. 
•Text is automatically translated into 
electrically synthesized speech. 

• Parallel port driven or 

Plug-in compatible with APPLE II. 
•On board audio amplifier. 
•Sample Program for APPLE II on 

cassette 
SWEET-TALKER 
Assembled and Tested 

Parallel Port Circuit Card $139 

APPLE II Plug-in Card $149 

VORTRAX is a trademark of Federal Screw Works 



DISK-80 

EXPANSION INTERFACE 

FOR THE 

TRS-80 MODEL I 




As Featured In 
Byte Magazine, March 1981 

• Disk controller (4 drives) 

• Hardware data separator 
•Buffered TRS-bus connector 

• Real-time clock 

• Printer port (optional) 

DISK 80-ASSEMBLED & TESTED 

with 32K RAM $329.95 

Centronics Printer 

Port add $ 50.00 

DISK-80 pc board $ 48.00 

Printer/Power Supply 

pc board $ 16.00 

Complete Kit with 32K 

RAM and Printer Port $275.00 

TRS-80 is trademark of Tandy Corp. 



To Order: Call Toll Free • 1-800-645-3479 
(In N.Y. State Call: 1-516-374-6793) 
For Information Call: 1-516-374-6793 



MICROMINTINC. 
917 Midway 
Woodmere, N.Y. 11598 




158 Microcomputing, December 1981 



Listing continued. 




983G 


NEXT X 




9890 


RETURN 




9899 


• 
a 




9900 


I Data 




9901 


■ 




9910 


DATA Plot the Z-Chart , 2000 




95)12 


DATA Save data on diskr3000 




332.0 


fcfYfb ttafce new datarlOOO 




9' '22 


DATA Print ALL the datar4000 




9930 


DATA Get data from disKrSOOO 




9340 


DATA Print a sinsle years' data,6000 




9H50 


DATA Insert one years' datar7000 




9960 


DATA Terminate ? 900 




9981 


• 




9990 


IF ERCODE = 8 PRINT "Company went bankrupt . " : WAIT 5IG0T0 100 


9992 


PRINT "Error found in line M ?ERLINE 




9994 


PRINT "Error code was ";ERCODE 




9999 


END 






Listing 2. ZLIST.BAS. 
0001 : ZLIST.BAS 






0002 : 






0003 : Gene Embry 






0004 : 






0010 ON ERROR GOTO 9990 






0020 GOSUB 9800:: Proaram initialization 






0099 : 






0100 I Main 






oioi : 






OHO HOME 






0112 let digits=o:rjust=o 






0120 PRINT TAB(W-LEN(M*)/2) ;M*:PRINT 






0122 PRINT TAB(W-LEN(S*)/2) ;S*:PRINT > 






0128 PRINT [ 


More___± 







it** 



ate* s ' '<>** £s«* • * \& ^ »cc« sS 2^ 



\dO 



*** *°l£e >Vff **•<$> *? ,V 



is*** 



6e<* 






O^ 



cvr° c \>\A «ro^ v .o ° T ^ t>* * o^ r 







ALER INQUIRIES WELCOME 




jCjc 



"THE SOURCE For 

Personal Computer Software 

Books Games & 

Accessories 



DEPT CI 1Q25 INDUSTRIAL OR BENSENVILLE IL 6Q1Q6 129 7 

^353 




CONVERT YOUR SERIAL PRINTER TO PARALLEL 



NEW MODEL UPI-3 SERIAL PRINTER INTERFACE MAKES IT 
POSSIBLE TO CONNECT AN ASCII SERIAL PRINTER TO THE 
PARALLEL PRINTER PORT ON THE TRS-80. 

Software compatibility problems are totally eliminated because 
the TRS-80 "THINKS" that it has a parallel printer attached. 
NO MACHINE LANGUAGE DRIVER NEEDS TO BE LOADED 
INTO HIGH MEMORY BECAUSE THE DRIVER ROUTINE FOR 
THE UPI-3 IS ALREADY IN THE TRS80 ROM! SCRIPSIT, PENCIL, 
RSM 2. ST80D, NEWDOS, FORTRAN, BASIC etc. all work as if a 
parallel printer was in use. 

The VJP\-3 is completely self contained and ready to use. A 34 
conductor edge card connector plugs onto the parallel printer 
port of the model I Expansion Interface or onto the parallel 
printer port on the TRS-80 III. A DB25 socket mates with the 
cable from your serial printer. The UPI-3 converts the parallel 
output of the TRS-80 printer port into serial data in both the 
RS232-C and 20 MA. loop formats. 

SPEEDWAY ELECTRONICS ^229 

Division of Binary Devices 

11560 TIMBERLAKE LANE 
NOBLESVILLE, IN 46060 
(317)842-5020 



TRS 80 is a trademark ot Tandy 



VISA MasterCard 



Switch selectable options include: 

• Linefeed after Carriage Return 

• Handshake polarity (RS232-C) 

• Nulls after Carriage Return 

• 7 or 8 Data Bits per word 

• 1 or 2 Stop Bits per Word 

• Parity or No parity 

• ODD or EVEN Parity 



NOW 
AVAILABLE 
FOR 
MODEL II 



UPI-2 for TRS80 Model II 

UPI-3 for TRS80 Model I or 3 

UPI-4 for use with Model 1 and RS Printer 

Interface Cable (no expansion interface required) 

Manual only (may be applied to order) 

Ten day return privilege — 90 day warranty 

Shipping and Handling on all orders 

Specify BAUD rate 50-9600 BAUD 



$149.95 
$149.95 

$159.95 
$ 5.00 

$ 4.00 



^See List of Advertisers on page 210 



Microcomputing, December 1981 159 



r% 



LOWEST*PRICES 



on 



TRS-80 




Model II 64KS 3298 




Model IIM6K $839 




Line Printer VII. $329 

OKIDATA 

EPSON MX-70 
EPSON MX-80 



Microline 80 
Microline 82 



$394 
$499 

$389 
$4 79 



$ SAVE 



MOST ORDERS 

SHIPPED WITHIN 

ONE BUSINESS DAY 



$ 



VERBATIM DATALIFETM DISKETTES 
5 Winch (box of 10) $25.95 

8-inch Double-Density, $43.95 

* Payment Money Order Cashier $ 
Check. Certified Chech Personal 
Checks require 3 weeks to clear VISA. 
MASTERCMARGE — Add 3% 

WRITE OR CALL FOR OUR COMPLETE PRICE LIST. 

CALL (602) 458-2477 

All prices are mail order only ■»■■ 

RAND'S 

2185 E. FRY BLVD. 
o SIERRA VISTA, AZ 85635 

TRS-80 is a trademark of Tandy Corporation. 

160 Microcomputing, December 1981 



Listing 

0130 

0138 

0140 

0130 

0160 

0190 

0199 

0900 

0901 

0990 

0999 

1000 

1001 

1010 

1012 

1020 

1022 

1030 

1032 

1034 

1036 

1038 

1040 

1080 

1090 

1099 

5000 

5001 

5010 

5012 

5020 

5030 

5040 

5050 

5080 

5090 

5099 

8000 

8001 

8010 

8012 

8090 

8099 

8100 

8101 

8110 

8120 

8122 

8124 

8126 

8130 

8140 

8142 

8148 

8150 

8160 

8190 

8199 

8200 

8201 

8220 

8230 

8240 

8280 

8290 

8299 

9800 

9801 

9810 

9812 

9814 

9816 
9818 

9820 

9824 

9890 

9899 

9900 

9901 

9990 

9992 

9994 

9996 

9999 



continued. 

GOSUB 8000 :: Port 

PRINT "Gettina data" 

GOSUB 5000 : IGet data 

GOSUB 8100:: Print heading 

GOSUB 1000::Print the data 

G06UB 8200::Print underline 

• 

: Done 

END 

: Print data compacted 

• 

FOR Y » 1 TO 240 STEP 12 

LET T*=STR*<S(Yrl>> 

LET T$ = LEFT$(TSW2) 

PRINT #QrT*r 

FOR X « 1 TO 12 

LET A * S<Y+X-lr2> :B*S< Y+X-l r3> 

LET X**STR*<A>+ M /"+STR$(B> 

PRINT #QrTAB(T0»X) ?X*J 

NEXT X 

PRINT #G 

NEXT Y 

RETURN 

• 
■ 

: Get data from disk 

a 

OPEN #10rZ*::if can't open the line #9990 is called!! 
RECNO #10=1 
FOR X=l TO 240 

READ #10rS(Xrl) rS(Xr2)rS(Xr3) 

IF S(X,1)*0 THEN 5080 
NEXT X 
CLOSE #10 
RETURN 

: Port of print 

■ 

INPUT "Which port "rQ 

IF Q <> 3 THEN Q * 1 

RETURN 

■ 

I Print Heading 

• 

IF 0=1 THEN HOME 

PRINT #G,TAB<2*W>; M Entire data file" 

PRINT #GrTAB(2*H) ? "PLAN/BOOK INGS" 

PRINT #GrTAB(TO)?"Monthf — >" 

LET U**"« m :G0SUB 8200::Print underline 

PRINT #G,"Year"? 

FOR X * 1 TO 12 

PRINT #GrTAB(X»T0) JX; 

NEXT X 

PRINT #Q 

GOSUB 8200::Print underline 

RETURN 

• 

: Print underline 

■ 
■ 

FOR K=l TO 58 

PRINT #QrU*; 

NEXT K 

PRINT #G 

RETURN 

■ 
■ 

: Psm. Variables 

• 

DIM S(240r3) : !Data Array 

LET M*« M List z-chart data - compact form" 

let w=3o:line=o:to=9 
let a=o:b»o 

LET Yl*7i:Y2*90:: from 1971 to 1990 

LET Z** "ZCHART.DAT" 

LET S*»"Data from 19"+STR*< Yl >♦" to 19"+STR* ( Y2 ) 

RETURN 

■ 

: Data 

■ 
• 

PRINT 

IF ERCODE » 8 PRINT "Company went bankrupt .": WAIT SIGOTO 100 

PRINT "Error found in line "JERLINE 

PRINT "Error code was "JERCODE 

END 



WE WILL NOT BE UNDERSOLD 



DISK DRIVES 




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TELECOMMUNICATIONS 

PRENTICE STAR MODEM 1 -year guarantee $125 
UNIVERSAL DATA SYSTEMS UDS103LP $149 UDS103JP $215 

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MICRO-MODEM II $295 

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APPLE ACCESSORIES AND SOFTWARE 



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VISICALC $159.00 

VISITERM $119.00 

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APPLE CARDS $ CALL 

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FLIGHT SIMULATOR $29.00 

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to three weeks to clear. All prices are mail order only and are subject to change without notice. Call for shipping charges. 



dealer (national/international) inquiries invited Send for FREE Catalogue 



The CPU SHOP, 



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TWX: 710-348-1796 Massachusetts Residents call 617/242-3361 



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Microcomputing, December 1981 161 




'*&& 



Encyclopedia for the TRS-80 * 

What's the key to getting the most from your 
TRS-80*? No, it isn't disk drives or printers or joy- 
sticks. It's information. Without a continual sup- 
ply of information and ideas, you cannot realize 
the full potential of the TRS-80*. 

Our response to the clamor for additional infor- 
mation is the Encyclopedia for the TRS-80*, a ten- 
volume reference work of programs and articles 
carefully selected to help you make the most of 
your microcomputer. You can consider the 
volumes of the Encyclopedia to be an extension of 
the documentation that came with your TRS-80* 
Each book is full of material on programming 
techniques, business, language, hardware, games, 
tutorials, education, utilities and interfacing. 

Unlike conventional encyclopedias, the 
Encyclopedia for the TRS-80* will never become 
stale or out of date. That's because the volumes of 
the Encyclopedia are being issued one-at-a-time, 
approximately six weeks apart. This means that 
each new volume will reflect the latest develop- 
ments and discoveries, making this a living ency- 
clopedia for TRS-80* users. 

The first four volumes are being issued during 
1981 . The remaining volumes will be issued during 
the first half of 1982. The deluxe COLLECTOR'S 
EDITION has a handsome green and black hard 
cover with a dust jacket. 
A soft cover edition is also available. 

DEALERS Please request discount information 
and catalog when ordering. Mail Dealer orders 
ATT: Wayne Green Books Dealer Sales. 

WAYNE GREEN BOOKS 

A division of Wayne Green Inc j 

Pine Street 
Peterborough, NH 03458 



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Encyclopedia Loader 

The editors at Wayne Green Books want to help 
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By a special arrangement with Instant Soft- 
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Your encyclopedia provides the essential docu- 
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With Encyclopedia LoaderTM youll save hours 
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Save money with this introductory offer. 
Encyclopedia LoaderTM for Volume 1 of 
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To order specify EL8001 $12.95 . 



The Encyclopedia for the TRS-80 
is a Wayne Green publication. 
Encyclopedia Loader is manufac- 
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division of Wayne Green Inc. 
* TRS-80 is a trademark of Radio 
Shack division of Tandy Corp 



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Sailors go down to the sea, with their micros. 



A Salty Saga 



By Carle Collins 



Life aboard a Navy aircraft carrier 
can be exciting and busy, but 
much of it is boring. There is very lit- 
tle to do during the hours not spent 
actually working or on watch: no cor- 
ner pizza parlor where you can meet 
the gang for pizza and beer, no disco 
and no bowling alley. The average 
sailor contents himself with watching 
one-channel closed-circuit TV— if he 



ICl 


MCS6502 microprocessor 


IC2 


MCS6530-002 ROM/IO/timer 


IC3,IC4 


2114-L 1KX4RAM 


IC5,IC6 


SN7442 decoder 


IC7 


MCS6520 peripheral interface 




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IC8 


SN7404 hex inverter 


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SN7406 hex buffer 


ICU 


SN7400 Quad 2-input Nand 


Q1-Q6 


2N2906A transistor 


D1-D6 


FND507 LED display 


R1-R4 


3.3k ohm resistor 


R5 


560 ohm resistor 


R6 


330k ohm resistor 


R7-R12 


1 .Ok ohm resistor 


R13-R18 


220 ohm resistor 


R19-R25 


82 ohm resistor 


CI 


10 pF capacitor 


XTAL 


1.0 MHz crystal 


SI 


SPST slide switch 


S2.S3 


SPDT push-button switch 


Kbd 


20-key calculator keyboard 


Misc.=4 l /2x6 l /2 perforated board, socket, 


wire 






Parts list. 



doesn't like the show presented, too 
bad. The ambitious men may work 
extra hours, but this soon becomes 
boring. Reading is about the only 
other form of entertainment 
available. 

After a few weeks at sea, it is no 
wonder these guys blow off steam 
when they hit port. 

As a field engineer on contract to 
the government, I have lived and 
worked with sailors, and have exper- 
ienced the same problems. On a re- 
cent assignment, I tried a project 
aimed at helping relieve the boredom 
and increasing their knowledge. I 
had found that most of the sailors 
with whom I worked knew very little 
about integrated circuits, although 
they worked with them each day. 
They used computer-controlled sys- 
tems, automated test stations and 
other sophisticated equipment, but 
with the cookbook repair manuals, 
they did not really have to under- 
stand the circuitry involved. 

So I approached some of them with 
the idea of forming a class, where I 
would teach them about integrated 
circuits and bring them up-to-date on 
microprocessors and microcomput- 
ers. The response to my suggestion 
was overwhelming. Of the 30 people 
working in the shop to which I was 
assigned, 25 wanted to participate, 
including the shop supervisors. 

I set out to find a suitable textbook 
which would give a good, detailed ex- 



planation of the inner workings of a 
microprocessor and how it could be 
used in a system. My first stumbling 
block was getting books to review. 
Some readers may picture this as no 
task at all, since I only had to go to my 
nearest computer store and check 
over the books. Well, the nearest 
computer store happened to be about 
900 miles away, across the open sea. 
Since I was not a teacher at an es- 
tablished school, I had to buy any 
books I wanted to review. Needless 
to say, at the prices most vendors 
want for their publications, I didn't 
buy very many books just for review. 
Fortunately, I happened upon a re- 
view which credited the book's au- 
thor with a good overview of the de- 
vices available and enough substance 
to make it suitable for my use. So I 
rushed an order to Sybex for a copy of 
Rodnay Zaks' book, Microprocessors, 
from Chips to Systems. 

Ship to Shore 

Now, rushing an order to someone 
from a ship at sea is not the same as 
doing it from your home. There is no 
telephone to call in the order or check 
on its status, and if you think the mail 
system within the States presents a 



Address correspondence to Carle Collins, Rte. 2, 
Box 90-SC, Winter Garden, FL 32787. 



164 Microcomputing, December 1981 




problem, try the Fleet Postal Service. 
Well, about the time I was ready to 
try sending a carrier seagull, Zaks' 
book arrived. It seemed to fit our 
needs, so I collected the money and 
"rushed" another order for the 25 
books we needed for the course. 

While we were discussing the 
course one day, one of the men asked 
if he could build a microcomputer 
during the course. My response was, 
'Why not?" I began searching for a 
suitable computer at an affordable 
price, because naturally everyone 
else wanted to build one too. We got 
information on available kits, and, 
after looking them over, we decided 
the students would save money and 
learn more by actually building and 
debugging their own units from 
scratch. That way, they would cer- 
tainly get to know the system better 
than if they just plugged in some 
chips and hooked up a power supply. 
Since I was the engineer of the group, 
they asked me for a design sugges- 
tion. 

Fortune smiled again. A colleague 
joined the ship with his Heathkit 
Trainer, and a sailor from another 
shop heard of our course and told me 
of his KIM-1, which he was just com- 
pleting. This sailor also happened to 



have all the issues of Microcomputing 
on board. I was ecstatic. I wrote to 
every company I could find that 
made components for microproces- 
sors or computers, and, as might be 
expected, the responses ranged from 
nothing to fantastic. 

RCA sent two 1802 chips and com- 
plete literature on the COSMAC se- 
ries; Western Digital responded with 
several handsful of support chips and 
stacks of literature; Synertek sent 
detailed manuals on the 6500 series; 
Zilog sent manuals on the Z-80; and 
Intel sent catalog data on their prod- 
ucts. It was all useful in selecting a 
system. 



When I finally surfaced from my 
studies, I had a design. It would 
enable the student to build a simple 
microcomputer which he could pro- 
gram to perform simple tasks, and 
could eventually expand into a full- 
blown system if he wished. I based 
my decision on the availability of in- 
formation on the particular device/ 
system I selected, the price and avail- 
ability of components and the exist- 
ence of support hardware for future 
expansion. After evaluating all these 
points and the material I had avail- 
able, I chose the system shown in the 
schematic diagram (see Fig. 1.) 

The System 

The 6502/6530-002 combination 
provides a CPU with a monitor pro- 
gram which includes a keyboard rou- 
tine, display routine and a Teletype 
routine to which the student can pro- 
gress as he studies. We could have 
written our own monitor programs, 
but this approach was quicker and 
time was running out. We were head- 
ed overseas soon, to be faced with the 
added complications of foreign mail 
services. The 6530-002 was available 
through a vendor, and we had the 
KIM-1 to familiarize us with its char- 
acteristics. If I were to do it over, I 
would probably write the programs: 
I'm older and wiser now. 

At the current price of random ac- 
cess memory, it was economical to 
use the 2114Ls. With this much 
memory, the students could write so- 
phisticated programs in machine lan- 
guage, and even advance to video dis- 
play as their budgets and ability per- 
mitted. The low-power version of the 
chip provided almost twice as much 
memory, for the same power, as the 
standard. 

The seven-segment display used 
common-anode devices readily avail- 
able from several of the surplus 
houses, and was modeled to take ad- 



♦ 5V 




GND 



Fig. 3. Power supply. 

Microcomputing, December 1981 165 



vantage of the display routine in- 
herent in the 6530-002. 

The keyboard proved to be the 
most difficult problem. Hex keypads 
were available, at a price, and so 
were full 56-key/63-key keyboards, 
but the goal was an economical sys- 
tem which could be used and ex- 
panded at a later date. I finally found 
a 20-key calculator unit which might 
fit the bill. However, on its arrival I 
discovered it had one side of each 
switch connected to a common bus, 



and I wanted to use the matrix coding 
with the keyboard routine in the 
ROM/IO. Maybe the unit could be 
modified. Students carefully re- 
moved the push-button unit from the 
printed circuit board that formed the 
contacts and bus interconnections. 
The common bus was cut and #30 
wire added to form two groups of 
seven switches and one group of six. 
They used an outboard switch for the 
remaining required function. Fig. 2 
shows the before-and-after configu- 



rations of the keyboard unit. This 
portion of the work required some 
miniature soldering, but it could be 
done, with care, by a person with 
average skills. 

The 6520 PIA was intended as an 
option to be added as the students 
progressed. When they considered 
the minor cost, they elected to pur- 
chase these chips with the other parts 
in order to have the necessary I/O 
ports for interface with the outside 
world. The experimenter never has 



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BACK VIEW OF KEYPAD 
AS RECEIVED 



MODIFIED KEYPAD 



166 Microcomputing, December 1981 



Fig. 2. Keypad modifications. 




ATARI 

Computers 
for people; 




800 TM $749 

410 Recorder $59.00 

810 Disc Drive $444.00 

822 Printer $35900 

825 Printer $629 00 

830 Modem $159 00 

820 Printer $269.00 

850 Interface ^59 00 

New DOS 2 System $21 00 

CX70 Light Pen $64.00 

CX30 Paddle $18 00 

CX40 Joy Stick $18 00 

CX853 16K RAM $89 00 

Microtek 16K RAM $75 00 

Microtek 32K RAM $169.00 




400 



TM 



$329 



ATARI SOFTWARE 

CX404 Word Processor $1 19 00 

CX404 PILOT $68 00 

CX413 Microsoft Basic $68 00 

CX4101 Invitation To Programing I .... $17.00 

CX4102 Kingdom $13 00 

CX4103 Statistics $17 00 

CX4104 Mialing List $17 00 

CX4105 Blackjack $13 00 

CX4106 Invitation to Programing 2 $20 00 

CX4107 Biorythm $13 00 

CX4108 Hangman . $13 00 

CX4109 Graph It $17.00 

CX41 10 Touch Typing $20 00 

CX4111 SPACE INVADERS $17 00 

CX41 12 States & Capitals $13.00 

CX41 14 European Countries & Capitals $13 00 

CX41 15 Mortgage & Loan Analysis $13 00 

CX41 16 Personal Fitness Program $59 00 

CX4117 Invitation To Programing 3 $20 00 

CX41 18-20 Conversational Languages (ea.) $45 00 

CX4121 Energy Czar $13 00 

CXL4001 Educational Master $21.00 

CX6001 17 Talk & Teach Series (ea) $23 00 

CX8106 Bond Analysis $20 00 

CX8107 Stock Analysis $20.00 

CX8101 Stock Charting $20 00 

CXL4002 Basic Computing Language $46.00 

CXL4003 Assembler Editor $46 00 

CXL4004 Basketball $24 00 

CXL4005 Video Easel $24.00 

CXL4006 Super Breakout $30 00 

CXL4007 Music Composer $45 00 

CXL4009 Chess $30 00 

CXL4010 3D Tic Tac Toe $24.00 

CLS401 1 STAR RAIDERS $39 00 

CXL4012 MISSLE COMMAND $32 00 

CXL4013 ASTEROIDS $32 00 

CXL4015 TeleLink $20 00 

Visicalc $149 00 

Letter Perfect (Word Processor) $109.00 

Source $89 00 



C* commodore 




CBM 8032 $1149 

4016 $799 00 

4032 $999 99 

8096 $1795 00 

CBM4022 Printer $629 00 

Tally 8024 $1699 00 

CBM C2N Cassette Drive $69.00 

CBM4040 Dual Disk Drive $1039 00 

CBM8050 Dual Disk Drive $1349 00 

SOFTWARE 

WordPro3 Plus $229 00 

WordPro4 Plus $329 00 

Commodore Tax Package $399 00 

Visicalc $149 00 

BPI General Ledger $329 00 

OZZ Information System $329 00 

Dow Jones Portfolio $129 00 

Pascal $239.00 

Legal Time Accounting $449 00 

Word Craft 80 $289.00 

Create A Base $249 00 

Power $89 00 

Socket 2 Me $20 00 

Jinsam $Call 

MAGIC $ Call 




VIC 20 $259 



Vic TV Modual $19 00 

Vic Cassette $69 00 

Vic 6 Pack Program $44 00 

VIC1530 Commodore Datassette $69.00 

VIC1540 Disk Drive $499 00 

VIC1515 VIC Graphic Printer $399 00 

VIC1210 3K Memory Expander $32.00 

VIC1 1 10 8K Memory Expander $53.00 

VIC1011 RS232C Terminal Interface $43 00 

VIC1 1 12 VIC IEEE 488 Interface $86.00 

VIC121 1 VIC 20 Super Expander $53 00 

VIC1212 Programmers Aid Cartridge $45.00 

VIC1213 VICMON Machine Language Monitor $45 00 

VIC1901 VIC AVENGERS $23 00 

VIC1904 SUPERSLOT $23 .00 

VIC1906 SUPER ALIEN $19.00 

VIC1907 SUPER LANDER $23 00 

VIC1908 DRAW POKER $23 00 

VIC1909 MIDNIGHT DRIVE $23 00 

VT106A Recreation Pack A $44 00 

VT107A Home Calculation Pack A $44.00 

VT164 Programmable Character/Gramegraphics $12.0o 
VT232 VICTerm I Terminal Emulator $9 00 



19 



HEWLETT 
PACKARD 




HP»85$2595 



NEW' HP-125 $3295 00 

HP»83 $1795 00 

HP»85 16K Memory Module $249 00 

5' 4 " Dual Master Disc Drive $2129 00 

Graphics Plotter (7225B) $2079 00 

Call for HP Software Prices & Information 



fihTi Texas Instruments 




TI-99/4 $399 



PHC 004 T I 99/4 Home Computer $399 00 

PHP 1600 Telephone Coupler $169 00 

PHP 1700 RS-232 Accessories Interface $169 00 

PHP 1800 Disk Drive Controller $239 00 

PHP 1850 Disk Memory Drive $389 00 

PHP 2200 Memory Expansion (32K RAM) $239 00 

PHA 2100 R F Modulator $43 00 

PHP 1100 Wired Remote Controllers(Pair) $3100 

PHM 3006 Home Financial Decisions $26 00 

PHM 3013 Personal Record Keeping $43 00 

PHD 5001 Mailing List $60 00 

PHD 5021 Checkbook Manager $18 00 

PHM 3008 Video Chess $60 00 

PHM 3010 Physical Fitness $26 00 

PHM 3009 Football $26 00 

PHM 3018 Video Games I $26 00 

PHM 3024 Indoor Soccer $26 00 

PHM 3025 Mind Challengers $22 00 

PHM 3031 The Attack $35 00 

PHM 3032 Blasto $22 00 

PHM 3033 Blackjack and Poker $22 00 

PHM 3034 Hustle $22 00 

PHM.3036 Zero Zap $18 00 

PHM 3037 Hangman $18 00 

PHM 3038 Connect Four $18 00 

PHM 3039 Yahtzee $22 00 

PHM 3017 Terminal Emulator I $39 00 

PHM 3026 Extended Basic $88 00 

PHM 3035 Terminal Emulator !! $45 00 



DISCS 

Sycom Blank Disk (10) $29 00 

Maxell MD I $36 00 

Maxell MD II (10) $46 00 

PRINTERS 



Epson MX 70 

Epson MX-80 

Epson MX-80 FT 

Diablo 630 

TEC 1500 Starwnter 25cps 

TEC 1500 Starwnter 45cps 



Call for Prices 



$1495 00 
$1795 00 



No Risk, No Deposit On Phone Orders, COD or Credit Card, 
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sales tax Add 3 : - for Visa or M C Equipment 
is sub)ect to price change and availability without 
notice Please can between 1 1 AM & 6 PM 



^See List of Advertisers on page 210 






Microcomputing, December 1981 167 




CqmpuCquer 



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Apple ensemble-covers entire Apple 

II with r video 6 two stacked disk 

$18 96 

Full Apple II 12 96 

Apple ll Keyboard 7.9* 

Apple II Disk 3 96 

Apple II Dlsli (stacked two dlek). . 7 .96 

Apple III 14.96 

TAt-60 MOOCL I 

Keyboard 97.96 

Cassette 4.96 

Video Display 9.96* 

Package Offer 19.96* 

'NOTE- Add $300 lor Expansion 
Interlace 

TRS-80 5%" Disk $4 96 

Two Disk Cover (aide by side). 7 96 
TAMO MODEL II 

Entire Unit $22 96 

Keyboard Only 7.96 

Throe Disk Unit (6" Drives) 18.96 

TRS-60 MODEL Nl 

TRS-80 COLON COMPUTE* 9.96 

Line Printer I $16.96 

Line Printer II 9.96 

Line Printer III 15.96 

Line Printer IV 9.96 

Line Printer VI 14 96 

Daisy Wheel Printer II 16.96 

Quick Printer 1 9.95 

Quick Printer II 5.95 

CBM PET COMPUTERS 

CBM Pet 2001-4001 aerie* $12.95 

CBM Pet 8032 12.95 

CBM Pet 2040. 8050 Disk 12 96 

CBM Pet 2022. 4022 Printer 9.96 

CBM Pet 2023 Printer 7 95 

ATAP.I900 $1096 

Atari 400 9.96 

Atari 810 Disk 5.95 

Atari 425 Printer 9 96 

CROMEMCO SYSTEM THREE $19.96 
Cromemco 3100, 3102 CRT 18 95 

Cromemco 3779 Printer 16 95 

Cromemco 3703. 3704 Printer 18 95 
Cromemco 3355 Printer 15.96 

SUPERBRAIN $1995 

Emulator 19 95 

Intertube 1995 

Superstar 19 95 

HEATH COMPANY 

H-19. H-89 CRT $18 95 

H 17. H 77 Disk 9.95 

H-27, H-47 Disk 12.96 

H-8, H 1 1 Computers 12 95 

H 14 Printer 9.96 

H 34. H-44K. H 44 RO 15 95 

H-34, H-54 1595 

DIGITAL EQUIPMENT 

Data System Terminal $1995 

Decscope Terminal 19.95 

WT/78, VT/78 Terminal 19 95 

VT 100 Terminal 1695 

Decprinter 1 15 95 

Decwnter II. Ill 18 95 

Decwriter IV 1595 

OHIO SCIENTIFIC 

Superboardll $12 95 

CAP DF. single case 14 95 

CAP DF, stacked 19.95 

C2 single case 14 95 

C2 stacked 1995 

C2-OEM, long case 19.95 

C3 OEM long case 19 96 

C3-S1. single cese 14.95 

C3-S1, stecked 19 95 

WANO COMPUTERS 
CRT Terminal $1895 

2221 Printer 19.95 

222 1-W Printer 22.95 

2231 Printer 1995 

2261 Printer 19 95 



HEWLETT PACKARD 

86, S3 Computer $14 95 

7225A plotter 9.96 

8290 IM disk 9.96 

Plotter on disk outfit 12.96 

Compucolor II Entire Unit 16.96 

Compucolor II Keyboard 5.96 

Vector Graphic MZ Computer. . . 14.96 
Vector Graphic Mindless Terminal 

18.96 

MINIMAX II TERMINAL $18 96 

Minimax ll doubiedlak 9.96 

North Star Horizon 14.96 

Sorcerer 9.96 

Texas instruments 99/4 B 95 

Intercolor 3621 18.96 

Poly Morphic System 8813 Computer 

14.96 

Poly Morphic Keyboard 7.96 

Tano Outpost II 22.96 

NEC Astrs Computer 16.96 

SOL 20 Computer 14.96 

IMSAI 8080 14.96 

CRTs 

Televideo TV1 912 or 920 $14.96 

Hazeitine (one sizs fits all) 18.96 

SoroclQ'20 18.96 

Adds Terminals 25. 100. 960. etc 

19.98 

ADM-3 14.96 

Leedex Video 100 9.96 

Leedex Video 10040 12.96 

NEC JB 1201 Monitor 995 

Visuel Tech 200 20.96 

9 inch CRT 7.96 

12 inch CRT 9.95 

PRINTERS 

Epson MX 80 and MX 70 9 96 

C.ITOH Starwnter 15.95 

Okidata Microime 80 9.96 

Base 2 9.96 

MPI 88T 9.96 

Diablo630 15.95 

NEC Spinwriter with Keyboard 15.95 
NEC Spinwriter without Keyboard 

15.95 

Diablo with Keyboard 15.96 

Diablo without Keyboard 15.95 

Xerox with Keyboard 15.95 

Xerox without Keyboard 15.95 

Qume Sprint III 14.95 

Qume Sprint V with Keyboard 15.96 
Qume Sprint V without Keyboard 

15.95 

Teletype 43 12.98 

IDS 440. 445. 460 12.96 

Texas Instruments 800 Series. . . 18.96 

Trendcom 100 or 200 9.95 

Centronics 101 19.95 

700.701.702.703,704.753 18.95 

Centronics 779 16.95 

Centronics Pi. 730, 737 9.96 

Comprint 912 12.95 

Anadex DP8000 12 96 

Xymec HY Q1000 12.95 

Okidata 22, SL125. SL2S0 15 95 

DISK DRIVES 

Micropolis 1041, 1042, 1043. 1053 

$9 96 

vista Double Disk 9.95 

Vista 5%' Disk 6.95 

Matchless 5 v." Disk 6.95 

Lobo Double 8" Disk 9.95 

Loco 5% " Disk, 14" long 6 95 

Lobo 3. 2 3 3 3 06 

MPI B51 or B52 Disk 4 95 

Percom5% ' Disk 4.95 

IBM write 

DATA General write 

CPT write 



Send check or money order to 
Include $1.50 for postage and handling 
Overseas orders include $4.00 postage 

dealer inquires invited 
ClwiiCquea 

P.O. Box 324 (Dept. A) 
Mary Esther, FL 32569 
Phone (904) 243-5793 



*^90 



168 Microcomputing, December 1981 



enough I/O ports as he expands, so 
this seemed wise. 

The 12 V, 3 A transformer in the 
power supply (Fig. 3) may seem like 
overkill in such a small project, but 
this trainer was designed with expan- 
sion in mind. The unit allows the ex- 
perimenter considerable leeway in 
his system without having to imme- 
diately purchase another. The regula- 
tors supplied 5 V dc at 1.5 A and 12 V 
dc at 1.5 A. The 12 V supply was pro- 
vided for activation of devices in the 
interface, since 5 V relays and lamps 
are not as prevalent as 12 V devices. 

The construction method got 
almost as much consideration as the 
design, because I wanted the stu- 
dents to learn as much as possible 
while saving on the expense. I consid- 
ered printed circuit techniques, but 
rejected them in view of the virtual 
requirement for double-sided boards 
and the number of holes to be drilled 
to accommodate the sockets or chips. 
Based on their job experience, the 
students felt that being able to quick- 
ly substitute chips during trouble- 
shooting would be a great advantage, 
so sockets became necessary. All of 
them were familiar with wire-wrap- 
ping techniques, so we chose per- 
forated boards and wire-wrap 
sockets as the best compromise. 

About the time we were ready to 
begin construction, the first daisy- 
chain wire-wrapping tool appeared 
on the market, and we bought one to 
evaluate. One man went ahead and 
started his unit using conventional 
wire-wrap, but when the new tool ar- 
rived and he saw the first board 
wired with it, he dismantled his unit 
and started over. The advantages 
were immediately obvious. 

The layout of sockets and packag- 
ing of the units were left to the stu- 
dent and varied with individual taste. 
Some placed everything on one board 
and mounted it in a chassis of in- 
dividual design. Others simply used 
three modular pieces, with the CPU 
and support on one board, the key- 
board and display on another and the 
power supply built as a separate unit 
for use with other projects. Each stu- 
dent made a design he felt would be 
most useful to him. The only thing 
common to each was the numbering 
of sockets and components, so that 
one wire list and schematic would be 
sufficient. 

Two valuable lessons were learned 
during the construction. Wire-wrap- 
ping of the round leads found on dis- 
crete components resulted in inter- 



mittents as the circuits were used and 
tested, because the test probe caused 
the wraps to loosen. The basic 
premise of wire-wrap is that the 
square corners of the posts dig into 
the wire and prevent loosening of the 
wrap. We solved that problem with 
the round leads by pre-tinning each 
one with solder, making the wrap 
and then sweating the joint with a 
soldering iron. This resulted irv 
reliable joints which would with- 
stand the probes of test equipment 
and yet did not detract from the 
overall efficiency of the wire- 
wrapping technique. 

The other lesson was in the use of 
the polyethylene-insulated wire sent 
with the wire-wrap tool. Care must 
be taken to ensure that sufficient 
slack is left in each run of the wire to 
prevent chafing against posts or other 
wires. The insulation is very fragile 
and will quickly chafe and cause 
shorts, making troubleshooting very 
difficult. 

The students bought their parts as a 
group to take advantage of quantity 
discounts, and I acted as their pur- 
chasing agent. This is one task I don't 
want again! Between the mail hang- 
ups and the vendors' stock problems, 
a three-to-four-week task required 
four months, and I was asked every 
day, "Have you heard anything from 
our parts?" 

Sockets were the major problem 
and naturally the wiring had to wait 
until they were on hand. Most of the 
classroom training was complete 
before they all arrived and the work 
could begin. The students were thus 
more knowledgeable about the cir- 
cuitry, but the value of having ex- 
periments to perform with the lec- 
tures was lost. 

Shipshape 

In spite of all the problems that 
arose with this project, the overall re- 
sults were gratifying. The students 
completed their computers, and 
some expanded to larger systems and 
even got into robotics and word-pro- 
cessing systems. They had learned 
enough to proceed on their own, and 
used me only as a sounding board for 
their ideas. 

I recently received a call from one 
young man who left the Navy and got 
a job in industry. He told me that the 
training he got in that course directly 
enabled him to get his position with a 
large aerospace company. Results 
like this compensate for most of the 
headaches. ■ 



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By William F. Luebbert 



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published — all in one place. 

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Apple is a registered trademark of Apple Computer, Inc. 



You may be using this little-known Boolean operation in a variety of ways and not realize it. 



More for the XOR 



By Allan D. Pratt 



0001 
0002 
0003 
0010 
0020 
0030 
0040 
0050 
0060 
0070 
0080 
0090 
0100 



•Simple Blinker Routine, to flash error message 
'Makes use of bit-flipping ability of XOR function 
•Written in Microsoft BASIC 
TEXT$* "Error! Hit spacebar to continue." 
STARS$«" ***** - 

BLANKS$«STRING$(LEN(TEXT$) ," ") 
IF INP(1)<> 13 THEN GOTO 100 

IF 1=0 THEN MIDDLE$=TEXT$ ELSE MIDDLE$=BLANKS$ 
1*1 XOR 1 

FOR J * 1 TO 30 0: NEXT J 'Delay Loop 
PRINT STARS$+MIDDLE$+STARS$;CHR$(13); 
GOTO 4 
PRINT: PRINT "Out of Loop" 

Listing 1. Blinker routine. 



0001 


• I is the 


value which will cycle thru the pattern. 


0002 


• J is the 


mask with which I is XORd to change it. 


0003 


• K is the 


mask with which J is XORd to flip it. 


0010 


INPUT I,J,K 


0020 


PRINT "J VALUE « "?J 


0030 


PRINT "K VALUE - ";K 


0040 


PRINT "STARTING VALUE OF I" ; I 


0050 


PRINT 




0060 


PRINT "CYCLE IS" 


0070 


FOR Z«l TO 


8 


0080 


J- J XOR K: 


I -I XOR J 


0090 


PRINT I ; 




0100 


NEXT Z 




0110 


PRINT 




0120 


GOTO 10 




Input values 


Sample results 


I«0, 


J-l, K-l 


0,1,1,0,0,1,1,0 


1-1, 


J«l, K«l 


1,0,0,1,1,0,0,1 


1-0, 


J«0, K«l 


1,1,0,0,1,1,0,0 


I«l, 


J-0, K-l 


0,0,1,1,0,0,1,1 

Listing 2. Double XOR loop. 



In the November 1980 issue of Mi- 
crocomputing, Alan Sclawy de- 
scribed an encryption scheme based 
on the use of the XOR function 
("CP/M Encryption Prescription, p. 
42). This same function can be used 
in some other interesting ways. For 
instance, you can use XOR to "flip a 
switch" back and forth, so that the 
program will first do one thing, then a 
second thing, then the first again, 
then the second again, and so on in- 
definitely. 

XOR stands for Exclusive OR. It is 
one of the less-used Boolean opera- 
tions. It is generally, if unclear ly, ex- 
plained as "either A or B but not 
both." For example: 

ABA XOR B 
1 1 
1 1 

1 1 



In each case, if either A or B is 1, 
and the other is 0, the result is 1, but 
if A and B are the same— either both 
l's or both 0's— the result is 0. 

This doesn't seem particularly use- 
ful. But as Sclawy points out, there is 
another way to look at this operation. 
The effect of this operator is that if 
the B bit is 1, the A bit is flipped to its 
opposite state, while if the B bit is 0, 
the A bit is unchanged. We can con- 
sider the B bit— or, for that matter, 



Address correspondence to Allan D. Pratt, 
Graduate Library School, University of Arizona, 
Tucson, AZ 85721. 



170 Microcomputing, December 1981 




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J 



the entire byte to the right of the XOR 
operator— as a selective mask. Now, 
consider what happens when you 
XOR an eight-bit byte with itself. Us- 
ing 1 for an example, we have: 

Bit 7 6 5 4 3 2 10 

110 1 (ASCII code for digit 1) 
00 11000 1 (Again, same pattern of bits) 

XOR 00000000 (Result is all zeros) 

Now, if we XOR this result with our 
original number again, we come back 
to that original number, thus: 

Bit 7 6 5 4 3 2 10 

00000000 (Result after first XOR) 
00 1 1 000 1 (Pattern for digit 1) 

XOR 1 10 1 (Result is back to original 

value) 

In BASIC, we could have 

0010 X = X XOR 1 
0020 PRINT X; 
0030 GOTO 10 

If we assume that X has not been 
assigned any previous value, and is 
therefore equal to zero, this will re- 
sult in the printing of a continuous 
pattern of alternating l's and O's 
across the screen. This will work for 
any value up to 32767, in Microsoft 
BASIC at any rate. This value is one- 
half the maximum integer value the 
system can handle, so XORing it with 
itself will give all zeros. Any bigger 
number causes an overflow. If we 
XOR with 45, for example, instead of 
1 in line 10, we will get a pattern of 
alternating 45s and O's. 

Applications 

This flip-flop operation can be put 
to good use in a variety of ways. For 
example, it could be used in a text 
processor to alternately print page 
numbers on the right and left sides of 
the page. Another use is shown in 
Listing 1, in which XOR is used as a 
blinker control. This short routine 
demonstrates the printing of an error 
message which flashes until the oper- 
ator takes some appropriate action. 

The error message TEXTS is 
printed on the screen, bracketed by 
asterisks. The MIDDLES of the 
printed line is alternately replaced by 
BLANKSS or TEXTS, depending on 
the value of I (0 or 1), with a delay 
loop between cycles. The process 
continues to cycle until you hit any 
key except CR. The CHR$(13) in- 
struction at the end of line 80 is a car- 
riage return for the cursor. This, and 
the semicolon at the end, keeps the 
printing and blanking on the same 
line, rather than running it down the 
screen. Modifications of this general 
idea, by getting TEXTS from a string 
array of error messages, or changing 



the operator's action and options as 
required, are fairly simple to invent. 
This same idea can be used in com- 
putational programs. In some equa- 
tions, for example, the sign of each 
term alternates. An instance of this is 

(l+x)- 1 = l-x + x 2 -x3 + x 4 -. . . 

You can create this alternating-sign 
effect easily with XOR. The brief pro- 
gram below demonstrates the effect 
of various simple combinations of nu- 
merical values which will cause these 
alternating patterns to appear: 

10 INPUT A,B 
20 FOR 1=1 TO 8 
30A-AXORB 
40 PRINT A; 
50 NEXT I 
60 PRINT 
70 GOTO 10 
80 END 

Some examples are: 

A B Result 

1 1 0,1,0,1,0... 

1 1,0,1,0,1... 

-1 -1 0,-1,0,-1,0... 

-1 -1,0,-1,0,-1... 
-1 -2 1,-1,1,-1,1... 

1 -2 -1,1,-1,1,-1... 

This XOR switching ability can be 
nested as well, to produce some more 
interesting patterns. You might, for 
example, want to execute some sub- 
routine twice, then a second one 
twice, then the first one twice again, 
and so on. A pattern of alternating 
0,0,1,1,. . . can be produced; or 1,1,0, 
. . . ; or 1,0,0, 1 . . . ; or any of several 
other combinations. 

Let I be the value which you want 
to cycle through the pattern. J is the 
mask against which I will be XORed. 
J is itself XORed against some con- 
stant, K, which will cause it to flip 
back and forth between two values. 
Since J flips between two values, I 
will vary over four different ones, 
though in some cases, there will be 
two values, which occur in pairs. The 
program in Listing 2 will let you ex- 
periment with various combinations 
of I, J and K. 

One of particular interest is 1 = 3, 
J= 1 and K = 2. This will result in 0,1, 
2,3,0,1,2,3 giving a four-beat cycle. 
This would allow the selection of four 
different subroutines in a recurring 
pattern. 

It is possible to extend this notion 
further, with yet another nested 
XOR, but beyond two levels, keeping 
track of what is going on will become 
too complicated to be worth the trou- 
ble. To control over four options it is 
probably better to use a more con- 
ventional technique, such as a 
counter or a FOR-NEXT loop.B 



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Microcomputing, December 1981 173 



Here's a quick and easy hardware modification that puts the Bytesaver in its place. 



A Spacesaver 
For the Bytesaver II 



By George S. Losey 



The Cromemco Bytesaver II is a 
handy S-100 memory board, but 
it does have limitations. On the posi- 
tive side it can house and program up 
to 8K bytes of programmable read- 
only memory (PROM) and reside in 
any of eight memory banks. It can be 
selected for DMA (direct memory ac- 
cess) even when it resides in an inac- 
tive bank and is overlapped by an- 
other board in an active bank (as long 
as the other board also has DMA 
override features). 

Unfortunately, the Bytesaver is also 
a memory hog. My Z-2 uses only IK 
or 2K of PROM, but when those ad- 
dresses are active, the entire 8K is ac- 
tive. The Bytesaver will drive the 
data bus high when any of the empty 
PROM sockets are addressed. If 
other memory occupies the same ad- 
dress, a bus conflict is created with 
disastrous results. 

I was able to live with this minor 
inconvenience until I installed a 
Dataspeed disk controller. It has a 
PROM that demands exclusive use of 
IK of memory at F000 (hex). The 
Cromemco monitor demands IK at 
E000. Placing the Bytesaver in the 
highest page of memory to keep the 

Address correspondence to George S. Losey, 
University of Hawaii at Manoa, PO Box 1346, 
Coconut Island, Kaneohe, HI 96744. 

174 Microcomputing, December 1981 



monitor happy made it impossible to 
use the disk controller. 

Since it does me little good to have 
a resident monitor that lives in an in- 
active memory bank, I set out to 
modify the board. The modification 
had to fulfill three goals. First, it had 
to be nondestructive. I hate cutting 



entire 8K of PROM space. 

Finally, I demanded that it be sim- 
ple and cheap, since I spend too 
much time on this stuff anyway. 

The modification I made costs 
about $1, takes 20 minutes to com- 
plete and fulfills all of my goals. It 
uses an SPST switch (switch 8, 



Since it does me little good 

to have a resident monitor 

that lives in an inactive memory bank, 

I set out to modify the board. 



foils and then having to solder them 
back after discovering my supposed 
improvements only resulted in mess- 
ing up a perfectly good board. 

Second, it had to allow the Byte- 
saver to be switch-selected to occupy 
either an entire 8K page of memory 
or restrict itself to the lowest IK 
region of the page. In this manner, it 
could house my IK monitor and not 
interfere with the disk controller. I 
could then devote the remaining 6K 
of space to RAM by using a Thinker- 
toy Memory Master 16K board se- 
lected to have a IK window for both 
the monitor and for the disk control- 
ler. Or, when desired, I could pop the 
top off the computer and select the 



ADDR/CONTROL bank) and two 
74LS00 gates (IC1). In its simplest 
form it adds one restriction: The 
DMA OVERRIDE and DMA IN/OUT 
switches can't both be on when the 
special IK ONLY option is selected. 
This causes a few problems and vs 
discussed fully below. 

Before going any further, you 
should correct an error in the July 1, 
1979, Bytesaver II manual. If your 
board is like mine (revision C), your 
manual may well be wrong. The per- 
son who drew the schematic, revi- 
sion 3 (p. 26 of the manual), was right 
on target; but whoever drew the fig- 
ures in part II was confused. The 
DMA OVERRIDE and DMA IN/OUT 



MTU Introduces 




Computer 



The MTU-1 30 " computer is THE COMPLETE 6502 system. 
This desktop system is designed for people who need to max- 
imize their computing and minimize their learning time. It gives 
you the features you need to perform your applications. 

A desktop computer should have clean expansion beyond the 
standard system . The MTU-1 30 is designed with an 1 8 bit ad- 
dress bus for up to 256K memory (80K standard) and includes 
an internal card cage for expansion boards or your own custom 
boards when needed . Of course, the power supply and fan have 
sufficient capacity for expansion . We even have provided rear 
panel cutouts for custom connectors if you need them for that 
special task you have to perform. 

The human interface features of this system include: a 96 key 
keyboard with programmable function keys and displayed soft 
legends, a bit mapped display with 480 x 256 pixel resolution 
graphics, 80 column text (gray scale also), an 8 bit audio port for 
speech, music and sounds, and a high speed (60 points/sec) 
fiber optic light pen. Other standard I/O includes 2 parallel ports 
with handshaking and a serial port with software selectable 
50-1 9.2K baud-rates. Of course connectors are provided on the 
rear panel. 

You interact with the MTU-1 30 through our field proven Chan- 
nel Oriented Disk Operating System (CODOS) which permits 
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is transferred from disk to anywhere in memory at a sustained 
speed of 19.6K bytes/second (not burst speeds!). Files are 
handled automatically, freeing you to perform at your peak. 
Auto-execution of ' 'jobs" when power is turned on can turn the 
MTU-1 30 into a dedicated-function system. A monitor with 32 
commands and 1 9 utilities is standard . Text or data can be easily 
transferred to or from other systems on IBM or CP/M* (or others) 
format disks with our optional DISKEX u program. 

Our standard full screen EDITOR allows you to edit text or pro- 
gram files with rapid positioning anywhere in the file. It edits any 
file size that fits on the disk (not just in memory) and will edit a file 
in place or save a backup copy. The concept ' 'what you 
see on the display is what exists in the file" has 
been employed which significantly reduces 
your learning and interacting time. This is a 
very powerful tool usable by anyone. 



If your needs include software development, you will find our op- 
tional MOS Technology compatible ASSEMBLER and 
DISASSEMBLER extremely fast, significantly reducing your 
development time. For example, a 21 OK byte source program 
with 6300 lines and 800 symbols can be assembled in less than 
4 minutes. This includes generating the object file and the listing 
with sorted symbol table and cross reference map on disk. This 
can be accomplished on a standard 1 -drive MTU-1 30-1 S. 

If you prefer to program in high level languages, keep in mind 
that the MTU-1 30 is RAM-based, not ROM-based, giving you the 
maximum memory possible for the use with any language. Our 
version of MICROSOFT BASIC is standard with MTU-1 30 
systems. It allows libraries of commands to be added when 
needed such as our Virtual (floating point) Graphics. PASCAL 
and FORTH are planned. 

The base standard MTU-1 30-1 S system comes with one single- 
sided, double-density 8" floppy disk, a 12" green phosphor 
CRT, and MTU-BASIC for $3995. The 3 other models contain 1 
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drives, languages or CRT for $2640. 4 Megabyte systems 
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We obviously cannot describe fully all of the details of the 
MTU-1 30 in this advertisement. If you want to know more about 
this complete desktop computer, call or write for our complete 
28 page descriptive literature. International requests include 
$5.00 U.S. 

COME TO MTU - for excellence in microcomputing systems. 

* C P/M is a trademark of Digital Research 





*^154 



Micro Technology Unlimited 

O Box 12106 
2806 Hillsborough St 
Raleigh NC USA 27605 
(919) 833 1458 




t'See List of Advertisers on page 210 



Microcomputing, December 1981 175 





$ 149 9J > 

DISKETTE AND MANUAL 



• Uses CP/M or MP/M operat- 
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CP/M. MP/M and TRS-80 are registered TM's 



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a subset of ANSI-74, features: 

• Copy statement for library handling. 
•CALL. .USING. ..CANCEL 

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• Interactive ACCEPT/DISPLAY 

• RELATIVE (random) access files. 

• Sequential files both fixed and 
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• DISPLAY, 16-bit binary or packed 
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WE WELCOME C.O.D's 



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SHARE YOCJR 
IDEAS 

Wayne Green Books announces 

April 1, 1982 deadline for 

submission of new manuscripts 

for consideration for 

the Fall Book List. 





Sales Opportunity 



Join a fast growing company 
involved in the microcomputer 
industry as a direct salesman. 
Sales involve our wide selection 
of books, four publications, soft- 
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publications. We are looking for a 
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If you or someone you know is inter- 
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strictest of confidence. 

Personnel Dept. 
80(C) Pine St. 
Wayne Green Inc. ^4oe 
Peterborough, N.H. 03458 



1 76 Microcomputing, December 1981 



switches in the ADDR/CONTROL 
bank are reversed in figures 2, 3, 4 
and 10. Switch No. 2 is the DMA 
IN/OUT and switch No. 3 is the DMA 
OVERRIDE. DMA does not work 
very well unless you change these 
figures. 

Kwp \\ Low 

The key to the modification is to 
keep the board enable signal from go- 
ing high unless bus address signals, 
A10, All and A12 are all low; i.e., 
unless the lowest IK PROM is ad- 
dressed. Board enable is a wired 
AND of several lines. If one of the 
several inverter gates is kept low, 
board enable remains low. 

The simplest approach that I could 
find is to keep the NAND output at 
pin 3 of IC 1 high. I used the unused 
switch (no. 8) in the ADDR/CON- 
TROL switch bank (renamed as the 
IK ONLY switch), one of the unused 
NAND gates in IC 1, and two OR 
gates in a 74LS32 that was added to 
the board. In the circuit shown in Fig. 
1, the OR gates decode A10, All and 
A12 and drive the extra NAND. The 
NAND, when the IK ONLY switch is 
closed (on), holds input pin 1 on IC 1 
low when any of the three address 
lines are high. This causes pin 3 of IC 
1 to remain high and board enable to 
remain low. When the IK ONLY 
switch is open (off), the entire 8K 
board is addressed. 

Note that when the IK ONLY 
switch is closed, if both the DMA IN/ 
OUT and DMA OVERRIDE switches 
are closed, the 74LS04 inverter is 
placed in a wired AND with the 
74LS00 gate that has been added. 
This is a no-no with totem pole out- 
puts, so this board should never be 
configured with all switches closed. 
However, the only time that both 
DMA switches are closed is when the 
board is residing in an inactive mem- 
ory bank but is to be selected for 
DMA addressing during a read. One 
would rarely want to perform a DMA 
read from a PROM. If this was need- 
ed, the IK ONLY switch might as 
well be open at any rate since the 
board is not selected. 

I decided that having a potentially 
dangerous switch combination was 
less evil than cutting foils to modify 
the circuit. If you decide that you 
don't mind cutting foils, a solution is 
at hand that demands only three ad- 
ditional resistors (Fig. 2). First, a 
74LS33 must be used in place of the 
74LS32 used above. The two extra 
OR gates are used as buffers in order 



to implement a wired AND. Pull-up 
resistors must be added to the OR 
gates used to decode A10, All and 
A 12. The foil connection between pin 
4 of RN2 and pin 1 of IC 1 is severed. 
Pin 4 of RN2 is led to both inputs of 
one of the extra OR gates, and the 
output from the IK ONLY switch is 
led to both inputs of the other extra 
OR gate. The outputs of both OR 
gates are placed in common as a 
wired AND with a Ik, 1/4 watt pull- 
up resistor and connected to pin 1 of 
IC 1. The wired AND is now imple- 
mented and you can fiddle with the 
switches to your heart's content. 

Construction of the modification 
can be done without cutting foils. A 
1/2-inch x 3/16-inch chip of plexi- 
glass is epoxied to the component 
side of the board with a 14-pin 
socket epoxied to it so that the solder- 
ing pins do not contact the board. 
Run a few lengths of wire-wrap wire 
through convenient holes on the 
board and solder in place. Be careful 
not to damage the insulation on these 
wires where they lead through these 
holes. The holes are plated through 
connections, and shorts could lead to 
very uninteresting results. The modi- 



fied board has the same vertical 
clearance as the original board and 
can fit into a tightly packed S-100 bus. 

If you have some time on your 
hands and desire a fancier solution, a 
more complex circuit could put any 
combination of the eight PROMS out 
of commission. An additional 74LS42 
(1 of 8 decoder), eight 74LS36 (exclu- 
sive OR gates) and a bank of eight 
switches would be required. The A, B 
and C inputs of the 74LS42 are con- 
nected to the A10, All and A12 bus 
inputs. The D input of the 74LS42 
must be tied to ground. The switches 
and exclusive OR gates are then con- 
nected, similar to the existing A 13, 
A14 and A15 logic. The exclusive 
ORs are then all connected with a Ik 
pull-up resistor in a wired AND. The 
wired AND output is then used in 
place of the OR output in the previ- 
ous solution. Note that you cannot 
use the existing 74LS42 for this pur- 
pose. The D input for this chip is 
generated by board enable— your 
board would never be enabled. 

I have used my modified board at 
both 2 and 4 MHz speeds without any 
problem. This spacesaver for the 
Bytesaver II works well.H 




Fig. 1 . Schematic for Bytesaver II modification. ICs 1, 14 and 1 9 correspond to the factory schematic. Bold 
lines indicate the added IC 29 and its connections. With this circuit, if switch 8 is closed, the DMA 
IN/OUT and DMA OVERRIDE switches cannot both be closed at the same time. 




♦5V 



IK 



& 



74LS33 



37 



87 



33 



AIO 
All 

AI2 



Fig. 2. Schematic for alternate Bytesaver II modification. This circuit lacks the switch closure restrictions 
of the circuit in Fig. 1. The factory-printed connection between pin 4 ofRN2 has been severed. Bold lines 
indicate added parts (IC 29 and three 1/4 W resistors) and their connections. 

Microcomputing, December 1981 177 



nbEflLER DIRKTORYHI 



El Monte, CA 

Ohio Scientific specialist in the San 
Gabriel Valley serving greater Los 
Angeles. Full product line on dis- 
play. Specializing in business com- 
puters. In-house service. Custom 
programming. Terminals. Printers. 
Open Mon-Sat, 9 AM-7 PM. Com- 
puter & Video, 3380 Flair Dr., 
Suite 207, El Monte, CA 91731. 
572-7292. 

N. Hollywood, CA 

Wholesale prices to dealers &. com- 
puter club members! Anadex, Cen- 
tronics, Corvus, Delta, Diablo, Ep- 
son, Godbout, Hayes, IDS, C. Itoh, 
Micro Pro, Mountain Computer, 
NEC, Novation, Okidata, Qume, 
TI, Televideo, Vector Graphic, Vis- 
ta, Zenith 6*. others. Patio Com- 
puter Sales Co., Suite 204, 5451 
Laurel Canyon Blvd., N. Holly- 
wood, CA 91607. 762-0020. 



Riverside, CA 

Visit our Computer Support Center 
for the Inland Empire's largest selec- 
tion of ICs, books and computer ac- 
cessories. Open daily. Check our 
prices and friendly service. Inland 
Electro-Mart, 8624 California 
Ave., Riverside, CA 92504. 687- 
3776. 

San Jose, CA 

New and used computer products — 
specializing in S-100 boards, print- 
ers, drives, chasses and complete 
systems, as well as supplies and parts 
— Imsai, Tandon, Diablo— 5000 sq. 
ft. WAV Component Supply, 
Inc., 1771 Junction Ave., San 
Jose, CA 95112. 



San Jose, CA 

Bay area's newest computer software 
store. Featuring Instant Software for 
the TRS-80, Apple, magazines, 
books. Shaver Radio, 1378 S. 
Bascom Ave., San Jose, CA 
95128.998-1103. 

Gainesville, FL 

Florida's most knowledgeable com- 
puter dealer. Apple computer (and 
S-100) sales and service. Peripherals, 
books, magazines, software, classes, 
consulting, supplies and engineering. 
Computer System Resources, 
Inc., 3222 SW 35th Blvd., 
Gainesville, FL 32608. 376- 
4276. 



Melbourne, FL 

Sales, service and leasing for Apple, 
SD systems, Altos, Atari, Mountain 
Computer, Intersystems, Epson, 
Anadex and Paper Tiger. Software, 
books, and magazines. Systems con- 
sulting. Mail order. H.l.S. Com- 
putermation, Inc., 1295 Cypress 
Ave., Melbourne, FL. 254-9399. 



Nokomis, FL 

We are the leading area computer 
store. We carry Cromemco, Apple, 
Vector Graphic; printers &. termi- 
nals. We offer full software support 
including G/L, A/R, payroll &l 
word processing. Computer Cen- 
tre, 909 S. Tamiami Trail, 
Nokomis, FL 33555. 484-1028. 

Sarasota, FL 

Your personal and business comput- 
er store for Dynabyte, Vector, 
HP-85, Atari and Epson. Structured 
Systems and Micro-Pro software. 
Computer furniture and books by 
Osborne or Hayden. Sales, service 
and supplies. Computer Cross- 
roads, 3800 S. Tamiami Trail, 
Sarasota, FL 33579. 349-0200. 

Aurora, IL 

Microcomputer systems for home or 
business; peripherals, software, 
books & magazines. Apple, Hewlett- 
Packard Series 80 Systems, HP Cal- 
culators, IDS, Qume, Starwriter 
printers. Farnsworth Computer 
Center, 1891 N. Farnsworth 
Ave., Aurora, IL 60505. 851- 
3888. 



Herington, KS 

Hardware support. Maintenance 
and service for all microcomputers 
and peripherals. Kits assembled or 
debugged. Radio Shack (mods OK) 
repaired. Quality work, fast turn- 
around and reasonable cost. Prairie 
Micro Clinic, Box 325, Hering- 
ton, KS 67449. 258-2179. 



Pasadena, MD 

Altos, Apple, Osborne, Atari — sys- 
tems, software, service. Not just an- 
other computer store! We're a full- 
service problem solving center for 
small businesses. Computer Cross- 
roads, Inc., 9143G Red Branch 
Rd., Columbia, MD; 8220 
Ritchie Hwy., Pasadena, MD. 
730-5513/647-7111. 



Garden City, Ml 

Books, magazines, hardware and 
software for Apple, North Star, 
TRS-80 and PET. Computer Cen- 
ter, 28251 Ford Rd., Garden 
City, Ml 48135. 425-2470. 

Lodi, NJ 

Computer hardware: North Star, Ze- 
nith, Atari, CBM/PET, Qume, Ep- 
son and others. Software: EduWare, 
Professional Software, Zenith, North 
Star, Programma, Personal Software 
and others. Factory trained service 
dept. Books, magazines, etc. Full 
product line on display. Comtek 
Electronics, Inc., Rt. 46 West, 
Lodi, NJ. 472-2440. 

River Edge, NJ 

Discount software — up to 25% off 
business, utility, recreational, educa- 
tional and home programs. Apple, 
Atari, TRS-80 and PET. Atari com- 
puters always on sale. Software 
City, 111 Grand Ave., River 
Edge, NJ 07661. 

Chautauqua, NY 

Retail book store featuring the Disas- 
sembled Handbook for TRS-80 Vol- 
umes 1, 2, 3. English, German &. 
French language editions. 9 AM- 5 PM 
weekdays. Come and visit us. Rich- 
craft Computer Book Store, 1 
Wahmeda Ave., Chautauqua, 
NY 14722. 753-2654. 

Rome, NY 

New and experienced computers, 
printers, modems. Software ex- 
change. VHS video equip., blank 
tapes, rated movies. List includes 
(send SASE): PET, SSB, TRS-80, 
SWTP, Panasonic, VCX. Video 
Computer Center, Box 1285- 
408, W. Liberty St., Rome, NY 
13440. 336-0266. 

Staten Island, 
Brooklyn, NY 

Computer hardware: North Star, Ze- 
nith, Atari, CBM-PET, Qume, Ep- 
son and others, Software: EduWare, 
Professional Software, Zenith, North 
Star, Programma, Personal Software 
and others. Factory trained service 
department. Books, magazines, etc. 
Full product line on display. Com- 
tek Electronics Inc., Staten Is- 
land Mall, Staten Island, NY. 
698-7050; Coney Island Ave. 
and Ave. X, Brooklyn, NY. 332- 
5933. 



Mississauga, Ontario 

I.D.S. brings Digital Research's Big 
Board into Canada. Bare boards, 
kits, or fully assembled single board 
computers plus many CP/M based 
business and utility software. Inno- 
tech Digital Systems, 50 Elm 
Drive East, Suite 1804, Missis- 
sauga, Ontario, L5A 3X2, Cana- 
da. 277-2222. 

Portland, OR 

Ohio Scientific specialists for 
business and personal computers. 
Local service. Terminals, printers, 
custom programming. Full OSI prod- 
uct line on display! 10 AM to 6 PM 
M-F. Fial Computer, 11266 SE 
21st Ave., Milwaukie, OR 
97222. 654-9574. 



Montreal, Quebec 

We do expert service on all micro- 
computers and peripherals, (CRT, 
printer, floppy disk) North Star, 
Hazeltine, Cromemco, Centronics, 
Shugart, Siemens, Apple, TRS, Ep- 
son, S-100. Montreal Data Cen- 
tre, 120 Ricard, Legardeur, 
Montreal, Quebec. 585-8801. 

Woodbridge, VA 

Computer/word-processing systems 
for business, school, home. Software, 
disk drives, printers. Books, maga- 
zines, supplies. Authorized CBM/ 
PET dealer, service. Consulting, 
training, maintenance contracts. 
MWF noon-8 TM, Saturday 9 AM-3 
tm. Virginia Micro Systems, 
Inc., 14415 Jefferson Davis 
Highway, Woodbridge, VA 
22191. 491-6502, Washington 
Metro 643-1063. 

Spokane, WA 

SS-50 Users: Expand present system 
to maximum or build from ground 
up. We provide PCBs for mother- 
boards, interfaces, etc. Write for 
specs and information. Quality Re- 
search Company, PO Box 7207, 
Spokane, WA 99207. 



Tell your dealer 

you saw this ad 

in Kilobaud Microcomputing . 



Dealers: Listings are $15 per month in prepaid quarterly payments, or one yearly payment of $150, also prepaid. Ads include 25 words describing your prod- 
ucts and services plus your company name, address and phone. (No area codes or merchandise prices, please.) Call Marcia at 603-924-7138 or write Kilobaud Mi- 
crocomputing, Ad Department, Peterborough, NH 03458. 




PRICE BREAKTHROUGH 



I6K RAM BOARDS FOR 

APPLE JUST $129.95 



HAVE NOU BEEN WAITING FOR THE COST 
OF EXPANSION BOARDS TO COME DOWN? 
NOUR WAIT IS OVER. UP UNTIL NOW RAM 
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PROUD TO ANNOUNCE THE ARRIVAL OF A 
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NOW NOU CAN RUN PASCAL, FORTRAN, 
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AT $129.95, OMEGAS RAMEX 16 IS THE 
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WELL, NOU GIVE UP HAVING TO REMOVE 
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MOTHER BOARD. THAT'S IT. WHAT NOU 
GET IS A SIMPLE, RELIABLE, BOARD 
THAT JUST PLUGS IN. MEMORN REFRESH 
IS ACCOMPLISHED ON THE BOARD 
ITSELF. 



THE RAMEX 16 IS GUARANTEED NOT JU5T 
FOR 90 DANS. NOT EVEN 6 MONTHS.OUR 
WARRANTY IS FOR ONE FULL NEAR FROM 
DATE OF PURCHASE. WE WILL REPAIR OR 
REPLACE ANN BOARD THAT IS DEFECTIVE 
THROUGH MANUFACTURE FOR A PERIOD 
OF ONE NEAR AFTER PURCHt^SE PROVIDED 
THIS DAMAGE IS NOT USER INFLICTED. 

ORDER NOUR RAMEX 16 NOW BN CALLING 
TOLL FREE 1-800-835-2246. KANSAS 
RESIDENTS CALL 1-800-362-2421. 
MASTERCARD OR VISA ACCEPTED OR 
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ANOTHER QUALITN PQOOUZT FROM 
OMEGA MICROWARE, INC. ^ 201 

FORMERLN OMEGA SOFTWARE 
PRODUCTS, INC. 
222 SO. RIVERSIDE PLAZA 
CHICAGO, IL 60606 
PHONE 3I2-648-I944 

©OMEGA MICROWARE, INC. 

APPLE AND APPLESOFT ACE REGISTERED 
TRADEMARKS OF APPLE COMPUTER. INC. PASCAL IS A 
REGISTERED TRADEMARK OF THE REGENTS OF THE 
UNIV. OF CA. SAN DIEGO. VISICAlC IS A REGISTERED 
TR/VDEMARK OF PERSONAL SOFTWARE. CPM IS A 
REGISTERED TRADEMARK OF DIGITAL RESEARCH INC. 
Z80 IS A REGISTERED TRADMARK OF ZILOG, INC. 
SOFTCARD IS A REGISTERED TRADMARK OF 
MICROSOFT. 



J 




See List of Advertisers on page 210 



Microcomputing, December 1981 179 



CLUB NOTES 



Japanese 
Computer Clubs 

Japanese computer clubs 
wish to contact U.S. clubs to 
exchange ideas, software, etc. 
Please send information in- 
cluding club name, size, 
when formed and type of ac- 
tivity to ORII, PO Box 1358, 
Mountain View, CA 94042. 



Fairfield, CT TRS-80 

The Fairfield County 
TRS-80 User's Group meets 
on the first Tuesday of every 
month at 7:30 pm at the New 
Canaan Country School. 

Contact Fairfield County 
TRS-80 Users Group, Alan 
Abrahamson, 10 Richlee 
Road, Norwalk, CT 06851. 
203-866-2670. 



Northeastern Ohio 
Heath User's Group 

The Northeastern Ohio 
Heath Users Group (NOHUG) 
meets the second and fourth 
Thursday each month from 
7-9 pm at the Maple Heights 
Public Library (Cleveland 
suburb). Persons desiring in- 
formation about the club 
and/or membership should 
contact Art Petkosek, 4705 
Tangle wood PI., Lorain, OH 
44053. 



The 

Philadelphia Area 
Computer Society 

The Philadelphia Area 
Computer Society meets in 
the LaSalle College Science 
Building at the corner of 20th 
and Olney Ave. The society 
has many user's groups in- 
cluding Apple, Atari, CP/M, 
Ohio Scientific, Pascal, PET, 
and TRS-80. Membership ap- 
plications should be sent to 
The Data Bus, PACS, Box 
1954, Philadelphia, PA 
19105. 215-925-5264. 

Northwest 
Computer Society 

The Northwest Computer 
Society meets in the Lemieux 
Library Auditorium, room 
115, Seattle University, the 
first and third Thursdays of 
each month at 7:30 pm. Mem- 
bership in the Society is open 
to anyone interested in per- 
sonal and small business 
computers. For more infor- 
mation write Northwest Com- 
puter Society, PO Box 4193, 
Seattle, WA 98104. 

Chicago TRS-80 
User's Group 

The Chicago TRS-80 User's 
Group meets the third 
Wednesday of every month at 
203 N. Wabash, Room 110, 
Chicago, IL, at 6 pm. TRS-80 
users are invited to attend. 



DAInamic 

DAInamic is a DAI personal 
computer user's group based 
in Belgium. The group has 
over 500 members in Bel- 
gium, Holland, Germany and 
France. They publish a bi- 
monthly newsletter with ar- 
ticles in English. 

For more information con- 
tact DAInamic, Heide 98. 
3171 Westmeerbeek, Belgium. 



Denver Amateur 
Computer Society 

The general meeting of the 
Denver Amateur Computer 
Society meets the third Wed- 
nesday of every month at 7 pm 
at the Educational Plaza, 7350 
N. Broadway (intersection of 
1-25 and Boulder Turnpike). 

For more information con- 
tact DACS, PO Box 1235, 
Englewood, CO 80150. 



CLAffl Fl EDS 



Classified advertisements are intended for use by persons desiring to buy, sell or trade used com- 
puter equipment. No commercial ads are accepted. 

Two sizes of ads are available. The $5 box allows up to S lines of about 35 characters per line, in- 
cluding spaces and punctuation. The $10 box allows up to 10 lines. Minimize use of capital letters 
to save space. No special layouts allowed. Payment is required in advance with ad copy. We can- 
not bill or accept credit. 

Advertising text and payment must reach us 60 days in advance of publication (i.e., copy for 
March issue, mailed in February, must be here by Jan. 1 ). The publisher reserves the right to refuse 
questionable or inapplicable advertisements. Mail copy with payment to: Ctaarifieds, Kilobaud 
Microcomputing, Peterborough, NH 03458. Do not include any other material with your ad as it 
may be delayed. 




"You programmed it wrong! That's what you get for not reading 
Kilobaud Microcomputing!" 

180 Microcomputing, December 1981 



For sale: SMD 13-inch color monitor $475. 
Apple silenttype printer w/2 rolls of paper 
$375. C1P w/8K RAM $300. Will bargain. 
Mike Kirk, 1205 Washington, Friona TX, 
79035. 



SWTP 6809, 56K, MPS, MP-LA, 1.5 MHz, 
$950. Dual 5.25-inch drives, PS, cabinet, 
$475. SWTP DC-4 DD ctlr w/FLEX9, TSC 
BASIC, tForth, Pascal, Sleuth, $325. SSB 
DC-A ctlr with DOS68.51C, CSS BASIC, 
Fortran, $250. Percom SBC/9, $90. More: 
817-461-2239. C. Shilling, Arlington, TX. 

For sale or trade: S-100 boards, ICs, power 
supplies, magazines, too many to list here. S. 
Rajabzadeh, 2666 Paganini Ave., San Jose, 
CA 95122. 408-238-2969. 

Hewlett-Packard HP-85 (32K) w/ROM draw- 
er, I/O ROM, printer/plotter ROM, RS232, 
cease, VC+ $3950. V.M. Faulkner, 317- 
289-4138. 



For sale: 32K Exidy Sorcerer $700. BASIC and 
development PACs each $50 extra. Comprint 
printer $350. R.L. Henne, 5870 Wood Flower, 
Burke, VA 22015. 703-250-5323. 



For sale: Centronics PI printer, perfect condi- 
tion, rarely used, 4 rolls of paper, paid $430, 
asking $200 or best offer. Philip Baily, 4758 
Kinglet, Houston, TX 77035. 713-729-6290.. 



Heathkit H89. Fully assembled with one drive, 
48K memory and HDOS operating system. 
Expertly built and tested by member of Kilo- 
baud Microcomputing staff. Featured on 
cover of March 1981 issue. Perfect condition. 
$1995. Jeff DeTray, 603-525^998, evenings. 

For sale: SWTP PR40 printer w/case of paper 
$125. Xitex video terminal, ex. $100. 2 SWTP 
4K mem. bds. $50 ea. Execuport printer termi- 
nal modem $250. 2 keyboards $10 ea. 2 MP1 
8-inch disk drives w/factory manual, $175 ea. 
or trade for 5-inch drives. Need an SWTP 
Mpa2 card. Warren V. BeU, 1604 N. Smith St., 
Spokane, WA 99207. 509-534-8088 eves., PST. 



For sale: 2114L2 memory chips, new — never 
used. All or part, $2.65 each. R. Van Cleave, 
256 S. Tucson Circle, Aurora, CO 80012. 
303-340-2955. 

For sale: Diablo 1640KSR daisywheel printers, 
one new and one used, $2150 and $1950. 
TRS-80 printer III, used, $1200. San Jose, 
CA, call Chris 415-494-4557. 



Free machine-language monitor for Elf II. 
Does all that the Netronics monitor does plus 
more and uses the terminal, not the hex key- 
pad. Runs in 1 .25K and can run from a PROM. 
Has a 300 baud software U ART and a parallel 
printer out routine. Please send name and ad- 
dress with $2 to cover reproduction and mail- 
ing to: John Ware, 2257 6th Ave., Ft. Worth, 
TX 761 10. 



Japanese computer clubs wish to contact U.S. 
clubs to exchange ideas, software, etc. Please 
send information including club name, size, 
when formed, type of activity, etc., to ORII, 
PO Box 1358, Mountain View, CA 94042. 

For sale: Radio Shack LP(I)-Centronics 779 
printer. Matrix-type with adjustable forms 
tractor. Unit just upgraded by Centronics. 
Like-new cond. $465. C. Okstein, 6 Storrs 
Rd., Willimantic, CT 06226. 203-487-1616. 



Magazines: Wanted — Interface Age: Dec '75, 
Jan '76, Feb '76, Mar '76, Sept *76, Dec '76, 
Mar '77, Apr '77; Byte: Feb '77. Any condi- 
tion, will pay top dollar for good condition. 
For Sale— Byte: July '76, Aug '76; Dr. Dobb's: 
Apr '77, Jan '78, May '78— $2.00 each. Call 
Andy Beck 201-370-9889 days, 370-9568 even- 
ings or write PO Box 571, Jackson, NJ 08527. 



For Sale: PET 8K with modem, joysticks, 
four voice music interfaces, and 150 pro- 
grams. $1 100 or best offer, plus shipping. Will 
cut price for high resolution color monitor. 
Call or write Rick Lucas, 12360 Kayla Lane, 
Houston, TX 77015. 713-455-5390 or 
713-453-2174. 



Rainbow Computing, inc 



Announces! 



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For the Apple II Computer 

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Microcomputing, December 1981 181 



19B1 
INDEX 



APPLE 

Apple Connections Deininger 122 Jan 

Space Race Hibernik 126 Jan 

Cheap, Dumb Apple Hubbard 65 Mar 

Auto-Menu for the Apple II Mi l es 68 Mar 

Crack That Code Vile 64 Apr 

A Rat s Eye View of Mazes McCarson 84 Apr 

Micros Say the Darn'dest Things Grady 92 Apr 

Apple Sector Counter Extraordinaire Peterson 113 Apr 

A Tale of Two Screen Dumps Hansen 174 Apr 

Inspiration from the Muse Goodfellow 53 May 

A Simple Text Processor Simpson 80 May 

The Animated Apple II Burlbaw 112 May 

To and Fro with Apple's Inverted Decimal Code Lancaster 98 Jun 

Poking the Apples Screen Moyer 102 Jun 

Mix It Upon Your Apple Bishop 108 Jul 

Electronic Orrery Gunther 150 Jul 

Apples Grow Well in Dallas Lukers 85 Aug 

To Tell the Truth Curtis 87 Aug 

°° s Mod King 106 Sep 

Zapple ll-What the Heck Is That? O'Brien 115 Oct 

Open Heart Surgery with an Apple Kanter 32 Nov 

Microsystems for the Dental/Medical Office Neiburger 48 Nov 

How Does the Apple III Stack Up? Kelley 72 Nov 

What You See Is What You Get Goodfellow 130 Nov 

Data Capture: Who Needs It? Goodfellow 80 Dec 

Stamp Out REMs Hitchcock 112 Dec 

APPLICATIONS 

TRS-80 in the Darkroom Busch 118 Jan 

A Minimum Accounting System Embry 135 Jan 

Dollars and Sense Embry 38 Mar 

Database Manager for the North Star Bailey 86 Mar 

Protect Your Files from Prying Eyes Hughes 106 Mar 

Tracking the Planets Maxey 130 Mar 

Quicksilver Micro System Marcus 42 Apr 

Find That Program! Baker 200 May 

Plan Your Retirement on Easy Street Brieger 50 Jun 

Once upon a Time Green 92 Jun 

6800 Disk-Based Mailing List Wolfe 143 Jul 

Electronic Orrery Gunther 150 Jul 

Get on the PET Instrument Bus Zubeldia 167 Jul 

To Tell the Truth Curtis 87 Aug 

Tape Library Coverage Setzer 130 Sep 

Little Gem Weather Forecaster Barlow 154 Sep 

What s On for Tomorrow? Vukcevich 156 Sep 

An Incredible High Speed Journey to the Stars Hodgson 172 Sep 

El Cheapo Word Processing Hafey 178 Sep 

An 1802 Phone Dialing System Bowley 94 Oct 

North Star Data Manager Benedict 118 Oct 

Normal Curve Plotter and Calculator Zimmerman 188 Oct 

PET Goes to the Polls Greenberg 195 Oct 

Take a Byte Out of Your Energy Bills Boudreaux 62 Dec 

ATARI 

Hidden Features Exposed Strom 180 Apr 

A Bright Star Comes into Focus Colsher 152 Apr 

Atari's Assembler Editor Baker 74 Jul 

182 Microcomputing, December 1981 



BUSINESS 

Aurelec: Making Micros in Indonesia Kaliaperumal 37 Feb 

Portrait of a Dynamic French Company David 72 Feb 

Computerize Your Rent-All Store Prather.Davis 136 Feb 

An Adventure in Free Enterprise Myers 116 Mar 

Microcomputer Selection and Implementation p ace 120 Mar 

Pascal Means Business Borgerson 46 Apr 

The Ultimate Information Juggler Wolfe 133 Apr 

Datal °8 Massa 118 May 

Put Your Micro on Wall Street Hart 126 Jul 

Apples Grow Well in Dallas Lukers 85 Aug 

Relief for the Hassled Clerk Shoemaker 162 Sep 

North Star Data Manager Benedict 118 Oct 

Put Your Micro on Wall Street Hart 134 Oct 

Focus in on Your Financial Picture Shreeve 52 Nov 

Made-to-Order Business Forms Deibert 80 Nov 

In Search of the Perfect Z Embry 148 r^c 

COMMUNICATIONS 

Modem Control Hayes Microcomputer Products 192 Jan 

Consumer Information Systems Derfler 50 Feb 

Turn Your Smart Computer into a Dumb Terminal Leavey 128 Feb 

Not-So- Dumb Dumb Terminal r^iy 208 May 

The Home Information Explosion Maloney 42 Oct 

Look At What's Available 43 Qct 

How Data Travels Parsons 46 Oct 

Micronet— From the User's End Eigsti 47 Oct 

Quiet-Computers in the Library Jenkins 58 Oct 

SearchHne Hartford 64 Oct 

Can Videotext Work? Urrows 68 q^ 

Videotext and Society Urrows 71 Oct 

Setting the Standards for the Industry 77 q^ 

Intelligence Networks in the Office Brandt 80 Oct 

The Case of the Data Busters Derfler 84 Oct 

Around the World with Videotext Urrows 84 Oct 

Predicting the Future with Electronic Mail Husbands 86 Oct 

CONSTRUCTION 

Assemble a Super Business System Lukers 29 Jan 

The Modem Eliminator Murray 112 Feb 

Build a Computer System and Display Board Hassall 117 Feb 

Building the H-89 m^^ ^ Mar 

Multiple Control with the Multifaceted H8 Wier 156 May 

Construct a Modular, Multi- Purpose Power Supply Hassall 61 Jul 

Clock/Calendar for the 6809 Rawson 132 Jul 

How To Cope with an Analog World T^Yasto "=*> K\*% 

Videographic Martinka 60 Aug 

Cool Down the H 14 H assall 130 Oct 

Arm the OSI with Parallel Ports Griffin 136 Nov 

Everyman's Computer System McKown, Sarns 32 Dec 

Poor Man's Memory Expansion for the OSI Young 56 Dec 

Printing Wizardry for Your Sorcerer Bergmann 76 Dec 

The Best of Both Worlds Wolfe 132 Dec 

EDUCATION 

The Microprocessor as Tutor Rgjd 95 i an 

Teaching Micros in Indonesia Kolopaking 32 Feb 

Island Computing Ed^ 44 Feb 

Math Can Be Fun Parry 128 Apr 

Teaching Our Kids Nelson 34 Sep 

Classroom of the Future Nii^n 36 ^p 



ISK DRIVES DISK DRI 

VES DISK DRIVES DIS 

HARD DISKS AND FLOPPIES FOR YOUR HEATH, RADIO SHACK, OSI, S-100 SYSTEMS 

5V4 DISK DRIVES (MODEL FDD-100-5b) 

SIEMENS 5 1 /4" drives are single sided, single or double density drives that are designed for years of 
trouble free service. These are the flippy models which other companies charge 1 5 to 30 dollars more 
for. The 5 1 /*" is the exact same one used in the HEATH systems, but check our price! . . . $250.00ea 

8" FLOPPY DISK DRIVES (MODEL FDD-100-8d) 

SIEMENS 8" drives are single sided, single or double density with simple power requirements. +24 and 
+5 VDC. It has automatic diskette ejection and a fail safe interlock that prevents the door from closing on 
a partially inserted diskette. The track to track time is as fast as 3ms. These drives are completely 
compatible with your MOD II, OSI, and many other systems $360.00ea 



ATTENTION HEATH H-88, 89 OWNERS 

HEATH owners, we now have the CDR controller card that allows you to use our 
8" drives on the H-88 or H-89 computers! You may mix any combination of 8" or 
5 1 /4"drives and also change your system to soft sectored formatting! Mix any 
combo single sided, double sided, single density or double density. We even 
include the zero origin prom. As a special offer we are giving you ALL 
necessary components with this system, even the patch for C/PM! 
A complete dual 8" system for the H-88 or H-89.. shipping incl. . . $1 600.00 





WINCHESTER TECHNOLOGY HARD DISK 

5 MB hard disk systems.for your HEATH H-88, H89, Radio Shack, MOD II, S-1 00 
systems. You get a 5 1 /4" 5mb formatted hard disk, power supply, cabinet, ali 
connecting and interface cables, interface and boot loader. Most of all its all 
preassembled tested burned in and ready to run! and as an added bonus we'll 
include a real time clock with date. Call or write for details, 1 mb available soon. 
This system is designed from the ground up and built of only commercial grade 
components. Price is just $2499.00 

8" SYSTEM PACKAGES 

One or two 8" SIEMENS drives with cabinet (choice of vertical or horizontal) power supply, all power 
connections, manuals and fan. A beautifully functional package built only of the best grade components. 
Availablefully assembled and tested for $100.00 more. 

Single 8" drive in dual cabinet (data cables extra) $665.00 

Dual drive package (data cables extra) $995 

5V4" WITH CASE AND POWER 

Our 5V4" drives are also available in system packages. One 5 1 /4" flippy in case 

with power supply tested $295.00 

2 drives in dual case $595.00 




CONNECTORS AND CABLES 

Power Connectors 8" $3.50 set 

Power Connectors 5V4" 1 .50 ea 

Edge Cards 8" or 5 1 /4 M 1 0.00 ea 

Ribbon Cable 1 .50 ft 

CP-206 dual 8" supply 1 00.00 ea 

Maintenance manuals 1 3.00 ea 

Custom made data cables Call 

Spare parts for SIEMENS drives. Call with 
your requirements. 
quantity discounts available, dealer inquiries invited 



PAYMENT POLICY 

We accept Mastercard. Visa, personal checks. MO. COD 
with PRIOR PERMISSION ONLY. (CASH will be required). 
We reserve the right to wait 10 working days for personal 
checks to clear your bank before we ship. Shipping charges 
MUST be included or your order will be delayed. All charges 
are standard UPS rates plus insurance. 

NJ residents must add 5% sales tax... no exceptions. 






PRICES & SPECIFICATIONS 
SUBJECT TO CHANGE 




VKA 



• some of the 8" packages require minor assembly 



FLOPPY DISKSERVICES, INC 



C.N. 521 2 

PRINCETON, NEW JERSEY 08540 



PHONE INQUIRIES WELCOME 9AM to 5PM (ET) 

609-771-0374 



191 



MOD II. CP/M are trademarks of Tandy and Digital Research respectively. 



Learning with Logo at the Lamplighter School 42 Sep 

Logo and the Great Debate Carter 48 Sep 

Whither Goes the Turtle? Rousseau, Smith 52 Sep 

David Moursund: Educating the Educators Hager 56 Sep 

Through a New Looking Glass Olds 62 Sep 

Logo and the Exceptional Child Weir 76 Sep 

Educational Computing— The Giant Awakes Prentice 86 Sep 

Tame That Blackboard Jungle Ingram 92 Sep 

Which Courseware Is Right for You? Holznagel 138 Oct 

Become A Troubleshooter— In 34 Easy Lessons Hassall 182 Oct 

Micros in an Educational Cooperative Brown 214 Oct 

Put to the Test by a Computer Meuer 178 Nov 

ELF 

An 1802 Phone Dialing System Bowley 94 Oct 

1802 Editor/ Assembler Erick 162 Nov 

ENCRYPTION 

Protect Your Files from Prying Eyes Hughes 106 Mar 

Crack That Code Vile 64 Apr 

EXIDY SORCERER 

Word Wizardry with Wordstar Strom 180 Apr 

The Verdict on Spellbinder Guralnick 72 May 

Sure Cure For Those "?SN ERROR Blues Henne 142 May 

Teach a Sorcerer New Tricks McCabe 76 Jun 

New Improved Sorcerer Graphics Vener 116 Jul 

The Sorcerer Speaks Vernon 146 Aug 

Printing Wizardry for Your Sorcerer Bergmann 76 Dec 

GAMES 

Scramble Rager 78$ Jan 

Space Race Hibernik 126 Jan 

The Fifteen Puzzle Colsher 114 Feb 

Computerized Table Tennis, Anyone? Cook 168 Apr 

Number Squares Leavey 132 Jun 

Nature Red in Tooth and Claw Carlson 158 Jun 

Hot Rod Graphics Greenwood 120 Jul 

GENERAL INTEREST 

Managing the Small System Environment Roberts 43 Jan 

Finishing School for Programmers Goodfellow 200 Jan 

Micros in the Land of the Pharaohs Case 26 Feb 



Enjoy The 



SEXPLOSION 



Subscribe Today 

Take a break from the space 
wars and shoot 'em ups. The 
Dirty Book will bring you the 
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(504) 455-5330 



The U.S.: A View from the U.K Bradbeer 54 Feb 

London Computer Club a Huge Success Bradbeer 56 Feb 

The Argentine Connection Winter 60 Feb 

The Skill of the Irish O'Connor 62 Feb 

The Micro Down Under Keay 69 Feb 

Microcomputer Selection and Implementation Pace 120 Mar 

Astrology and the Microcomputer Lehman 124 Mar 

An Industry Challenge: The Osborne I Computer Osborne 106 May 

The Ascent of Computers Avoli 108 Sep 

The Home Information Explosion: A Fizzle or a Bang? Maloney 42 Oct 

How to Write a Computer Program Carew 156 Oct 

WordStar RoadMap Perelman 176 Nov 

ASaltySaga Collins 164 Dec 

GRAPHICS 

A High-Stepping Plotter from Houston Instruments Cohan 101 Feb 

The Electric Crayon Roberts 72 Mar 

Dots Incredible! Conroy 83 Mar 

A Rat's Eye View of Mazes McCarson 84 Apr 

The Many Moves of APF Kenney, Keen 100 Apr 

A Tale of Two Screen Dumps Hansen 174 Apr 

The Animated Apple II Burlbaw 112 May 

TRS-80 Graphics on the Heath H-19 Shoemaker 92 Jul 

6800 High-Speed, High-Resolution Graphics Mayhugh 94 Jul 

A One-Two Punch for CBM/PET Graphics Froelich 104 Jul 

Mix It Up on Your Apple Bishop 108 Jul 

New, Improved Sorcerer Graphics Vener 116 Jul 

Hot Rod Graphics Greenwood 120 Jul 

Lights. . .Camera. . .Action Hansen 102 Nov 

Parti-Colored Picture Pad Shore, Williams 166 Nov 

HARDWARE REVIEW 

Real-Time Spectrum Analyzer Baker 48 Jan 

6801: A One-Chip System Neff 100 Jan 

A High-Stepping Plotter Cohan 101 Feb 

S.D. Sales' 80-Column Video Board Brooner 124 Feb 

Introducing the TRS-80 Pocket Computer Wadsworth 162 Feb 

A Bright Star Comes Into Focus Colsher 152 Apr 

Shift Into Extra Drive on Your Heath Thompson 80 Jul 

The Sorcerer Speaks Vernon 146 Aug 

Japanese Invasion: Part 1 Vose 101 Sep 

Scope It! Lukers 116 Sep 

What's So Super About the HP-85? King 120 Sep 

Plotting with the X-Y Recorder Roberts 150 Sep 

Japanese Invasion: Part2 Vose 90 Oct 

Expand Your Horizon Schweppe 160 Oct 

How Does the Apple III Stack Up? Kelley 72 Nov 

RCA's "Connection to the Computer World'' Derfler 94 Nov 

Japanese Invasion: Part 3 Vose 110 Nov 

The Secret World of the Superbrain Bregoli 52 Dec 

Data Capture: Who Needs It? Goodfellow 80 Dec 

IBM Thinks Small Vose 86 Dec 

Another Industry Giant Takes a Micro Step Nelson 94 Dec 

Brand- Name Shopping Nestor 95 Dec 

Japanese Invasion: Part IV Vose 140 Dec 

Relief for an Overstuffed SWTP Doonan 144 Dec 

HEATH 

Enhancing H8 BASIC Howell 130 Jan 

Getting the Most from Your H8 Skiff 95 Feb 

Building the H-89 Moore 28 Mar 

Datalog Massa 118 May 

Multiple Control with the Multifaceted H8 Wier 156 May 

Dissecting the HDOS Diskette Jorgenson 66 Jul 

Shift into Extra Drive on Your Heath Thompson 80 Jul 

TRS-80 Graphics on the Heath H-19 Shoemaker 92 Jul 

Tame That Blackboard Jungle Ingram 92 Sep 

Relief for the Hassled Clerk Shoemaker 162 Sep 

Cool Down the H 14 Hassall 130 Oct 

A Printer for the H89 Isenson 144 Oct 

The Heath/Phone Hookup Massa 162 Oct 

Made-to-Order Business Forms Deibert 80 Nov 

INTERFACING 

Apple Connections Deininger, Tujaka 122 Jan 

Second Cassette Interface with One IC Hutchinson 188 Jan 

Getting the Most from Your H8 Skiff 95 Feb 

Plotting with the Heath X-Y Recorder Roberts 150 Sep 

Let Your Micro Speak-2-U-2 Wieland 168 Sep 

An 1802 Phone Dialing System Bowley 94 Oct 

A Printer for the H89 Isenson 144 Oct 

Expand Your Horizon Schweppe 160 Oct 

Poor Man's Memory Expansion for the OSI Young 56 Dec 

KILOBAUD KLASSROOM 

Kilobaud Klassroom No.24 Stark 168 Jan 

MEDICAL 

Open Heart Surgery with an Apple Kanter 32 Nov 

Just What the Doctor Ordered Blight 40 Nov 



184 Microcomputing, December 1981 



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^169 



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Microcomputing, December 1981 185 




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Microsystems for the Dental/Medical Office Neiburger 48 Nov 

MODIFICATIONS 

Apple Connections Deininger, Tujaka 122 Jan 

Second Cassette Interface with One IC Hutchinson 188 Jan 

Cheap, Dumb Apple Hubbard 65 Mar 

Faster Baud Rate for the Superboard II Cassette Antonelli 112 Mar 

Energize Those OSI Peripheral Ports Jones 80 Apr 

Aim For Total Control Bazaral 102 May 

Name That Tune Davids 148 May 

A PIE Taster's Report Stone 179 May 

Soulful Software Sound Bell 195 May 

Not-So-Dumb Dumb Terminal Daly 208 May 

Light-Fingered Computing Haden 68 Jun 

A Proven Formula to Program 2716s Young 162 Jul 

Student- Proof Your Computer Reid 151 Aug 

DOS Mod King 106 Sep 

A Shortcut through the Gates Rifkin 182 Sep 

Putting the Joy Back into Programming Donato 66 Nov 

TRS-80 Printer for the PET Verzino 124 Nov 

A Spacesaver for the Bytesaver II Losey 174 Dec 

MUSIC/SOUND 

Simulation of Musical Instruments Chamberlin 53 Jan 

Computer Music the Easy Way Marum 60 Jan 

Simulation of Musical Instruments Chamberlin 142 Feb 

Name That Tune Davids 148 May 

Soulful Software Sounds Bell 195 May 

Let Your Micro Speak-2-U-2 Wieland 168 Sept 

Keep in Tune with the Times Shapiro 146 Nov 

NORTH STAR 

Word Processor for the North Star Disk System Haller 164 Jan 

Database Manager for the North Star Bailey 86 Mar 

Norty, Ronnie and Me Coudal 86 May 

Hippity-Hop Memory Test Work 166 May 

North Star Quiz Prisco 44 Jun 

Here's Where It's At Roby 74 Jun 

An Incredible High-Speed Journey to the Stars Hodgson 172 Sep 

El Cheapo Word Processing Hafey 178 Sep 

North Star Data Manager Benedict 118 Oct 

Expand Your Horizon Schweppe 160 Oct 

A Time Saver for Your Database Bailey 206 Oct 

Editing Enhancer Dean 212 Oct 

OSI 

Reverse Video for the OSI CI P Baker 176 Jan 

Autoloader Program for the CI P and Superboard II Kammer 158 Feb 

Save It with CASSY Messent 38 Apr 

Energize Those OSI Peripheral Ports Jones 80 Apr 

Computerized Table Tennis, Anyone? Cook 168 Apr 

OSI Screen-Clear Command Bradshaw 172 Apr 

Not-So- Dumb Dumb Terminal Daly 208 May 

OSI Baud Mod Carr 56 Jun 

Double-Good OSI Protection Cohen 96 Jun 

Dump It on Cassette Macauley 130 Jun 

Nature Red in Tooth and Claw Carlson 158 Jun 

Hot Rod Graphics Greenwood 120 Jul 

Micros in an Educational Cooperative Brown 214 Oct 

Arm the OSI with Parallel Ports Griffin 136 Nov 

Poor Man's Memory Expansion for the OSI Young 56 Dec 

PET 

Real-Time Spectrum Analyzer Baker 48 Jan 

Scramble Roger 78 Jan 

Second Cassette Interface with One IC Hutchinson 188 Jan 

Portrait of a Dynamic French Company David 72 Feb 

PET Shorthand Complete Ratliff 144 Mar 

A PIE Taster's Report Stone 179 May 

Soulful Software Sounds Bell 195 May 

Find That Program! Baker 200 May 

Once Upon A Time Green 92 Jun 

PET Memory Expansion Ratliff 177 Jun 

A One-Two Punch for CBM/PET Graphics Froelich 104 Jul 

Get on the PET Instrument Bus Zubeldia 167 Jul 

What's the Difference? Nottingham 152 Aug 

PET Goes to the Polls Greenberg 195 Oct 

Put the Joy Back into Programming Donato 66 Nov 

A BASIC Assembler for the PET Baker 114 Nov 

Put to the Test by a Computer Meuer 178 Nov 

PRINTERS 

A Tiger's Eye View of Computer Graphics Hansen 184 May 

Cool Down the H14 Hassall 130 Oct 

A Printer for the H89 Isenson 144 Oct 

PROGRAMMING TECHNIQUE 

MAT Functions Paturzo 138 Mar 

PET Shorthand Compleat Ratliff 144 Mar 



186 Microcomputing, December 1981 



THE UNIVERSAL ONLINE REFERENCE WORK 

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Oot Matrix Printer Interfaces with Apple II 

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^See List of Advertisers on page 210 



Microcomputing, December 1981 187 



A Sure Cure for "?SN Error" Blues Henne 142 May 

Here's Where It's At Roby 74 Jun 

Poking the Apple's Screen Moyer 102 Jun 

What's the Difference Nottingham 152 Aug 

The Z-80 Condensed Bishop 139 Sep 

Popping and Pushing Permutations in BASIC Wasserman 50 Dec 

Recursion: Solving Age-Old Mysteries MacDonald 104 Dec 

More for the XOR Pratt 170 Dec 

PROFILES 

On the Road with a TRS-80 Bobo 106 Jan 

Microcomputers in Industry Barney 106 Feb 

RFI 

FCC Takes Aim Against RFI Polluters Brown, Maloney 30 Apr 

Trying to Live in Harmony with Harmonics Derfler 36 Apr 

SOFTWARE REVIEW 

Word Processor for the North Star Disk System Haller 164 Jan 

Building the H-89- Part 2 Moore 116 Apr 

Word Wizardry with WordStar Strom 180 Apr 

Hot Rod Word Processors Piatt 40 May 

Word Processing Roundup Fowler, Dowden.Knecht, Head 45 May 

Inspiration from the Muse Goodfellow 53 May 

The Verdict on Spellbinder Guralnick 72 May 

Double Your Memory, Double Your Fun Hallen 190 May 

TSC Extended BASIC Hughes 154 Aug 

What You See Is What You Get Goodfellow 130 Nov 

Compiled vs Interpreted BASIC Lesser 180 Nov 

SPEECH 

Advances in Speech Synthesis Nickel 134 May 

The Sorcerer Speaks Vernon 146 Aug 

SWTP 

The SWTP Computer System Stark 82 Jan 

Go with the Flow Stark 102 Apr 

Math Can Be Fun Parry 128 Apr 

The Ultimate Information Juggler Wolfe 133 Apr 

Minding Your P' sand Q's Parry 58 Jun 

Number Squares Leavey 132 Jun 

6800 High-Speed, High-Resolution Graphics Mayhugh 94 Jul 

6800 Disk-Based Mailing List Wolfe 143 Jul 

TRS-80 

On the Road with a TRS-80 Bobo 106 Jan 

TRS-80 in the Darkroom Busch 118 Jan 

The Fifteen Puzzle Colsher 114 Feb 

Introducing the TRS-80 Pocket Computer Wadsworth 162 Feb 

Dots Incredible! Conroy 83 Mar 

Advances in Speech Synthesis Nickel 134 May 

TRS-80 Launchpad Sunday 134 Aug 

How to Maximize Profits Burns 158 Aug 

Little Gem Weather Forecaster Barlow 154 Sep 

Normal Curve Plotter and Calculator Zimmerman, Conrad 188 Oct 

TUTORIAL 

The SWTP Computer System Stark 82 Jan 

Data on Disk Fritzson 111 Jan 

For CP/M: Automatic Program Execution on Start-Up Lindsay 184 Jan 

Write Your Own FORTH Interpreter Fritzson 76 Feb 

Write Your Own Pseudo-FORTH Compiler Fritzson 44 Mar 

Thoughts on the 68XX System Stark 94 Mar 

Secret Codes Revealed Freed 58 Apr 

A Better Bubble Sort Harrison, Sachs 148 Apr 

The Wonderful World of Data Structures Windley 84 Jun 

Multiplying by l'sandO's Scanlon 110 Jun 

Dissecting the HDOS Diskette Jorgenson 66 Jul 

Firm Up Your Floppy with 800K Stark 36 Aug 

Sorting Techniques Explained Gentry 156 Nov 

UTILITY ROUTINES 

Blank Removal Prisco 40 Jan 

A Print Utility for CP/M Barbier 150 Feb 

Autoloader Program for the CI P and Superboard II Kammer 158 Feb 

Auto-Menu for the Apple II Miles 68 Mar 

Save It with CASSY Messent 38 Apr 

Apple Sector Counter Extraordinaire Peterson 113 Apr 

Sorta Super Fast Marino 164 Apr 

OSI Screen-Clear Command Bradshaw 172 Apr 

Teach a Sorcerer New Tricks McCabe 76 Jun 

To and Fro with Apple's Inverted Decimal Code Lancaster 98 Jun 

Dump It on Cassette Macauley 130 Jun 

An Atari Disassembler Colsher 142 Aug 

Clear Screen in the Blink of an Eye Powers 126 Sep 

Updating CP/M's STAT Utility Barbier 150 Oct 

Editing Enhancer Dean 212 Oct 

Surefire Timer Programs Bonnifield 62 Nov 

A BASIC Assembler for the PET Baker 114 Nov 

Stamp Out REMs Hitchcock 112 Dec 

188 Microcomputing, December 1981 



VIDEO 

Reverse Video for the OSI C1P Baker 176 Jan 

Videographic Martinka 60 Aug 

WORD PROCESSING 

Word Processor for the North Star Disk System Haller 164 Jan 

Processing Written Words Kitsz 32 May 

In Search of the Processed Word Anderton 34 May 

Hot Rod Word Processors Piatt 40 May 

Word Processing Roundup Dowden, Fowler, Knecht, Head 45 May 

Inspiration from the Muse Goodfellow 53 May 

6800s Best-Kept Secrets Stark 56 May 

Word Processing Directory 68 May 

The Verdict on Spellbinder Guralnick 72 May 

A Simple Text Processor Simpson 80 May 

Nortie, Ronnie and Me Coudal 86 May 

Beyond Gutenberg Woodbury 93 May 

Minding Your P'sandQ's Parry 58 Jun 

Word Processor Extraordinaire Hart 152 Jul 

El Cheapo Word Processing Hafey 178 Sep 

Word Processing and Me Hallen 218 Oct 

WordStar RoadMap Perelman 176 Nov 

What You See Is What You Get Goodfellow 130 Nov 

Z-80 (ALSO SEE TRS-80, EXIDY SORCERER) 

Secret Codes Revealed Freed 58 Apr 

Surefire Timer Programs Bonnifield 62 Noc 

1802 

Programming the 27 16 Merrin 212 May 

1802 Editor/ Assembler Erick 162 Nov 

6800, 6801, 6802, 6809 (ALSO SEE SWTP) 

The SWTP Computer System Stark 82 Jan 

A Minimum Accounting System Embry 135 Jan 

Kilobaud Klassroom Stark 168 Jan 

Turn Your Smart Computer into a Dumb Terminal Leavey 128 Feb 

Thoughts on the 68XX System Stark 94 Mar 

Protect Your Files from Prying Eyes Hughes 106 Mar 

Quicksilver Micro System Marcus 42 Apr 

6800's Best-Kept Secrets Stark 56 May 

Thoughts on the 68XX Systems Caudell, Silver 136 Jun 

Clock/Calendar for the 6809 Rawson 132 Jul 

TSC Extended BASIC Hughes 154 Aug 

Tape Library Coverage Setzer 130 Sep 

68XX Secrets Stark 116 Dec 

Relief for an Overstuffed SWTP Doonan 144 Dec 

8080 (ALSO SEE NORTH STAR) 

Computerize Your Rent-All Store Prather, Davis 136 Feb 

Sorta Super Fast Marino 164 Apr 



STATEMENT OF OWNERSHIP. MANAGEMENT AND CIRCULATION (Required 
by 39 U.S.C. 3685). 1. Title of publication. Kilobaud Microcomputing. 2. Date of 
filing. Oct. 1. 1981.3. Frequency of issue. Monthly. A. No. of issues published an- 
nually. 12. B. Annual subscription price. $25.00. 4. Location of known office of 
publication (Street. City. County. State and ZIP Code) (Not printers). 80 Pme 
Street. Peterborough. Hillsboro County. N.H. 03458. 5. Location of the headquar- 
ters or general business offices of the publishers (Not printers). 80 Pine Street. Pe- 
terborough. Hillsboro County. N.H. 03458. 6. Names and complete addresses of 
publisher, editor and managing editor. Publisher (Name and Address). Wayne 
Green. Peterborough. N.H. 03458. Editor (Name and Address). Wayne Green. Pe- 
terborough. N.H. 03458. Managing Editor (Name and Address). Dennis Brisson. 
Swanzey Lake Road. Winchester. N.H. 03470. 7. Owner (II owned by a corpora- 
tion, its name and address must be stated and also immediately thereunder the 
names and addresses of stockholders owning or holding 1 percent or more of total 
amount of stock. If not owned by a corporation, the names and addresses of the in- 
dividual owners must be given. If owned by a partnership or other unincorporated 
firm, its name and address, as well as that of each individual must be given. If the 
publication is published by a nonprofit organization, its name and address must be 
stated.) Name. 1001001. Inc.. Peterborough. N.H. 03458. Wayne Green. Peterbor- 
ough. N.H. 03458. 8. Known bondholders, mortgagees and other security holders 
owning or holding 1 percent or more of total amount of bonds, mortgages or other 
securities (If there are none, so state) Name. none. 9. For completion by nonprofit 
organizations authorized to mail at special rates (Section 132. 122. PSM) The pur- 
pose, function and nonprofit status of this organization and the exempt status lor 
Federal income tax purposes (Check one) Not applicable. 10. Extent and nature of 
circulation. (X) Average No. copies each issue during preceding 12 months. (Y) Ac- 
tual No. copies of single issue published nearest to filing date. A. Total No. of cop- 
ies printed (Net Press Run) (X) 90.670 (Y) 88.000. B. Paid circulation 1 . Sales 
through dealers and carriers, street vendors and counter sales. (X) 28.251 (Y) 
35.260. 2. Mail subscriptions (X) 54.594 (Y) 49.129. C. Total paid circulation 
(Sum of 10B1 and 10B2) (X) 82.845 (Y) 84.389. D. Free distribution by mail, car- 
rier or other means samples, complimentary, and other free copies (X) 540 (Y) 686. 
E. Total distribution (Sum of C and D) (X) 83.385 (Y) 85.075. F. Copies not dis- 
tributed 1. Office use. left over, unaccounted, spoiled after printing (X) 5466 
(Y) 1106. 2. Returns from news agents (X) 1819 (Y) 1819. G. Total (Sum 
of E. Fl and 2— should equal net press run shown in A) (X) 90.670 (Y) 88.000. 
11. I certify that the statements made by me above are correct and com- 
plete. Signature and title of editor, publisher, business manager, or owner. 
Debra Boudrieau. Business Manager. 



kb microcomputing book nook 




• TRS-80 ASSEMBLY LANQUAQE-BK121 7-by 
Hubert S. Howe, Jr. This book incorporates into a 
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perienced users. $9.95.* 

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programmers! This Is a comprehensive reference 
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the sophisticated routines they contain. It concisely 
explains set-ups, calling sequences, variable passage 
and I/O routines. Part II presents an entirely new com- 
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PROGRAMMING 

The Microprocessor Software Engineering Series by 

John Zarrells provides common sense descriptions of 
advanced computer system topics for engineers, pro- 
grammers and development managers. Each volume is 
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ware tools and techniques. Detailed glossary of tech- SfC 
nical jargon is included in each volume. This series will 
help you find the solutions to your software problems. 



• MICROCOMPUTING CODING SHEETS Microcom- 
puting's dozen or so programmers wouldn't try to work 
without these handy scratch pads, which help prevent 
the little errors that can cost hours and hours of pro- 

g ramming time. Available for programming is Assem- 
ly/Machine Language (PD1001), which has columns 
for address, instruction (3 bytes), source code (label, 
op code, operand) and comments; and for BASIC 
(PD1002) which is 72 columns wide. 50 sheets to a pad 
$2.39.* 



• OPERATING SYSTEMS: CONCEPTS AND PRINCI- 
PLES— BK1 193— Presents an overview of the basic op- 
erating system types, their components and capabil- 
ities. $7.95.* 

• WORD PROCESSING AND TEXT EDITING— BK1 194 

—Provides a firm basis for understanding word pro- 
cessing terminology and for comparing systems. 
$7.95.* 

• SYSTEM ARCHITECTURE- BK1 195 -Presents a 
detailed overview of advanced computer system 
design including object architecture and capability- 
based addressing. $9.95.* 



6502 



•Jf *THE APPLE II USER'S GUIDE— BK1220— by Lon 
Poole, Martin McNiff, and Steven Cook. This guide is 
the key to unlocking the full power of your Apple II or 
Apple II Plus. Topics include: "Applesoft and Integer 
BASIC Programming"— especially how to make the 
best use of Apple's sound, color and graphics capabili- 
ties. "Machine Level Programming," "Hardware 
Features"— which covers the disk drive and printer, 
and "Advanced Programming" — describing high 
resolution graphics techniques and other advanced 
applications. Well organized and easy to use. $15.00.* 

• PROGRAMMING THE 6502 (Third Edition)— BK 1005 
— Rodnay Zaks has designed a self-contained text to 
learn programming, using the 6502. It can be used by a 
person who has never programmed before, and should 
be of value to anyone using the 6502. The many exer- 
cises will allow you to test yourself and practice the 
concepts presented. $13.95.* 

• 6502 APPLICATIONS BOOK— BK1006— Rodnay Zaks 
presents practical-application techniques for the 6502 
microprocessor, assuming an elementary knowledge of 
microprocessor programming. You will build and design 
your own domestic-use systems and peripherals. Self- 
test exercises included. $12.95.* 

• 6502 ASSEMBLY LANGUAGE PROGRAMMING— 

BK1176— by Lance A. Leventhal. This book provides 
comprehensive coverage of the 6502 microprocessor 
assembly language. Leventhal covers over 80 program- 
ming examples from simple memory load loops to 
complete design projects. Features include 6502 as- 
sembler conventions, input/output devices and inter- 
facing methods, and programming the 6502 interrupt 
system. $16.99.* 

• 6502 SOFTWARE GOURMET GUIDE AND COOK- 
BOOK— BK1055— by Robert Findley. This book intro- 
duces the BASIC language programmer into the realm 
of machine-language programming. The description of 
the 6502 structure and instruction set, various 
routines, subroutines and programs are the ingredi- 
ents in this cookbook. "Recipes" are included to help 
you put together exactly the programs to suit your 
taste. $12.95.* 



68000/6809/8080 

• 6809 MICROCOMPUTER PROGRAMMING AND 
INTERFACING— BK1215— by Andrew C. Staugaard, 
Jr. Getting involved with Tandy's new Color Computer? 
If so, this new book from the Blacksburg Group will 
allow you to exploit the awesome power of the 
machine's 6809 microprocessor. Detailed information 
on processor architecture, addressing modes, register 
operation, data movement, arithmetic logic opera- 
tions, I/O and interfacing is provided, as well as a 
review section at the end of each chapter. Four appen- 
dices are included covering the 6809 instruction set, 
specification sheets of the 6809 family of processors, 
other 6800 series equipment and the 6809/6821 
Peripheral Interface Adapter. This book is a must for 
the serious Color Computer owner. $13.95.* 

^•68000 MICROPROCESSOR HANDBOOK-BK1216 

—by Gerry Kane. Whether you're currently using the 
68000, planning to use it, or simply curious about one 
of the newest and most powerful microprocessors, 
this handbook has all the answers. A clear presenta- 
tion of signal conversions, timing diagram conven- 
tions, functional logic, three different instruction set 
tables, exception processing, and family support 
devices provides more information about the 68000 
than the manufacturer's data sheets. A stand alone 
reference book which can also be used as a supple- 
ment to An Introduction to Microcomputers: Vol. 2 — 
Some Real Microprocessors. $6.99.* 

• 8080A/8085 ASSEMBLY LANGUAGE PROGRAM- 
MING— by Lance Leventhal— BK1004— Assembly lan- 
guage programming for the 8080A/8085 is explained 
with a description of the functions of assemblers and 
assembly instructions, and a discussion of basic soft- 
ware development concepts. Many fully debugged, 
practical programs are included as is a special section 
on structured programming. $15.99.* 

• 8080 SOFTWARE GOURMET GUIDE AND COOK- 
BOOK— BK1 102— If you have been spending too much 
time developing simple routines for your 8080, try this 
new book by Scelbi Computing and Robert Findley. De- 
scribes sorting, searching, and many other routines for 
the 8080 user. $12.95* 

—COOKBOOKS 

• CMOS COOKBOOK— BK1011— by Don Lancaster. 
Details the application of CMOS, the low power logic 
family suitable for most applications presently 
dominated by TTL. Required reading for every serious 
digital experimenter! $10.50.* 

• TVT COOKBOOK— bMU64— by Don Lancaster. De- 
scribes the use of a standard television receiver as a 
microprocessor CRT terminal. Explains and describes 
character generation, cursor control and interface in- 
formation in typical, easy-to-understand Lancaster 
style. $9.95.* 



*Use the order card in this magazine or itemize your order on a separate piece of 
paper and mail to Kilobaud Microcomputing Book Department • Peterborough NH 
03458. Be sure to include check or detailed credit card information. 



• TTL COOKBOOK— BK1063— by Don Lancaster. Ex- 
plains what TTL is, how it works, and how to use it. Dis- 
cusses practical applications, such as a digital coun- 
ter and display system, events counter, electronic 
stopwatch, digital voltmeter and a digital tachometer. 
$9.50.* 

No COD. orders accepted. All orders add $1.50 for first book, $1.00 each addi- 
tional book, $10.00 per book foreign airmail. Please allow 4-6 weeks for delivery. 
Questions regarding your order? Please write to customer Service at the follow- 



ing address. 

PRICES SUBJECT TO CHANGE WITHOUT NOTICE 



•#new 



FOR TOLL FREE ORDERING CALL 1-800-258-5473 




BASIC & PASCAL 



^Chaii 



**tU£ 



• INTRODUCTION TO TRS-80 LEVEL II BASIC AND 
COMPUTER PROGRAMMING- BK1219-by Michael 
P. Zabinski. Written by an experienced educator, this is 
the book for those beginners who want to learn about 
computers without having to become an expert. It has 
practical programs, useful line-by-line comments, ex- 
cellent flowcharts accompanied by line numbers and 
over 200 exercises which help the reader assess prog- 
ress, reinforce comprehension, and provide valuable 
practical experience. $10.95.* 

• 50 BASIC EXERCISES— BK1 192— by J. P. Lamoitier. 
This book is structured around the idea that the best 
way to learn a language is through actual practice. It 
contains 50 completely explained exercises: state- 
ment and analysis of the problem, flowcharts, pro- 
grams and actual runs. Program subjects include 
mathematics, business, games, and operations re- 
search, and are presented in varying levels of diffi- 
culty. This format enables anyone to learn BASIC rap- 
idly, checking their progress at each step. $12.95* 

• THE BASIC HANDBOOK — BK1174— SECOND EDI- 
TION— by David Lien. This book is unique. It is a virtual 
ENCYCLOPEDIA of BASIC. While not favoring one 
computer over another, it explains over 250 BASIC 
words, how to use them and alternate strategies. If a 
computer does not possess the capabilities of a need- 
ed or specified word, there are often ways to accom- 
plish the same function by using another word or com- 
bination of words. That's where the HANDBOOK 
comes in. It helps you get the most from your com- 
puter, be it a "bottom-of-the-line" micro or an oversized 
monster. $19.95.* 

• LEARNING LEVEL II — BK1 1 75— by David Lien. Writ- 
ten especially for the TRS-80, this book concentrates 
on Level II BASIC, exploring every important BASIC 
language capability. Updates are included for those 
who have studied the Level I User's Manual. Sections 
include: how to use the Editor, dual cassette opera- 
tion, printers and peripheral devices, and the conver- 
sion of Level I programs to Level II. $15.95.* 

• BASIC BASIC (2ND EDITION)— BK1026— by James 
S. Coan. This is a textbook which incorporates the 
learning of computer programming using the BASIC 
language with the teaching of mathematics. Over 100 
sample programs illustrate the techniques of the BA- 
SIC language and every section is followed by practi- 
cal problems. This second edition covers character 
string handling and the use of data files. $10.50.* 

• ADVANCED BASIC— BK1000— Applications, includ- 
ing strings and files, coordinate geometry, area, se- 
quences and series, simulation, graphing and games. 
$10.75*. 

• SIXTY CHALLENGING PROBLEMS WITH BASIC 
SOLUTIONS (2nd Edition)— BK1073— by Donald 
Spencer, provides the serious student of BASIC pro- 
gramming with interesting problems and solutions. No 
knowledge of math above algebra required. Includes a 
number of game programs, as well as programs for 
financial interest, conversions and numeric manipula- 
tions. $6.95* 




TheBAS*C 
Handbook 

Ot&C Com**** Lar*jM»w* 







• PASCAL— BK1 188— by Paul M. Chirlian. Professor 
Chirlian's textbook combines a simple approach to the 
PASCAL language with comprehensive coverage on 
how a computer works, how to use a flowchart, work- 
ing from a terminal as well as batch operation and 
debugging. Special attention is paid to idiosyncrasies 
of the language and syntax flowcharts abound for the 
convenience of the experienced programmer. Well in- 
dexed. $12.95* 

• INTRODUCTION TO PASCAL- BK1 189- by Rodnay 
Zaks. A step-by-step introduction for anyone wanting 
to learn the language quickly and completely. Each 
concept is explained simply and in a logical order. All 
features of the language are presented in a clear, easy- 
to-understand format with exercises to test the reader 
at the end of each chapter. It describes both standard 
PASCAL and UCSD PASCAL, the most widely used 
dialect for small computers. No computer or program- 
ming experience is necessary. $14.95.* 



• PROGRAMMING IN PASCAL— BK 11 40— by Peter 
Grogono. The computer programming language 
PASCAL was the first language to embody in a coher- 
ent way the concepts of structured programming, 
which has been defined by Edsger Dijkstra and C.A.R. 
Hoare. As such, it is a landmark in the development of 
programming languages. PASCAL was developed by 
Niklaus Wirth in Zurich; it is derived from the language 
ALGOL 60 but is more powerful and easier to use. 
PASCAL is now widely accepted as a useful language 
that can be efficiently implemented, and as an ex- 
cellent teaching tool. It does not assume knowledge of 
any other programming language; it is therefore suit- 
able for an introductory course. $12.95.* 



BUSINESS 



• THEORY Z—BK1226— How American Business Can 
Meet the Japanese Challenge— by William Ouchi. Why 
are the Japanese catching up and surpassing 
American industrial productivity? What allows 
Japanese industrialists to offer guaranteed lifetime 
employment to their workforce? This book will help 
you understand the Theory Z managerial philosophy 
and its implications for the American corporate future. 
Examples are given of the American industrial giants 
already operating under Z-style management, and the 
impact of this style on the quality ot their executives 
and workers is explored. A must for the alert business- 
man, large or small. $12.95.* 

• SO YOU ARE THINKING ABOUT A SMALL 
BUSINESS COMPUTER— BK1222— by Richard G. Can 
ning and Nancy C. Leeper. For a well-organized manual 
on the process of selecting the right computer system 
for your small business, this text can't be excelled. De- 
signed to introduce the novice in data and word pro- 
cessing to the real benefits of computerization, the 
book is filled with money- and time-saving tips, photos 
of equipment, lists of suppliers, prices, explanations 
of computer terminology, and helpful references to 
additional sources of information. Everyone con- 
templating a first computer installation should have 
this book. $14.00.* 

• PAYROLL WITH COST ACCOUNTING— IN BASIC— 

BK1001— by L. Poole & M. Borchers, includes program 
listings with remarks, descriptions, discussions of the 
principle behind each program, file layouts, and a com- 
plete user's manual with step-by-step instructions, 
flowcharts, and simple reports and CRT displays. Pay- 
roll and cost accounting features include separate 
payrolls for up to 10 companies, time-tested interac- 
tive data entry, easy correction of data entry errors, job 
costing (labor of distribution), check printing with full 
deduction and pay detail, and 16 different printed re- 
ports, including W-2 and 941 (in CBASIC). $20.00.* 

• SOME COMMON BASIC PROGRAMS— BK1053— 
published by Adam Osborne & Associates, Inc. Perfect 
for non-technical computerists requiring ready-to-use 
programs. Business programs, plus miscellaneous 
programs. Invaluable for the user who is not an ex- 
perienced programmer. All will operate in the stand- 
alone mode. $14.99 paperback. 

• PIMS: PERSONAL INFORMATION MANAGEMENT 

SYSTEM— BK1009— Learn how to unleash the power 
of a personal computer for your own benefit in this 
ready-to-use data-base management program. 
$11.95.* 

-MONEYMAKING- 






GAMES 



■MMmw * 

machine 



• 40 COMPUTER GAMES— BK7381 —Forty games in all 
in nine different categories. Games for large and small 
systems, and even a section on calculator games. Many 
versions of BASIC used and a wide variety of systems 
represented. A must for the serious computer games- 
man. $7.95* 

• BASIC COMPUTER GAMES-BK1074-Okay, so 
once you get your computer and are running in BASIC, 
then what? Then you need some programs in BASIC, 
that's what. This book has 101 games for you from very 
simple to real buggers. You get the games, a descrip- 
tion of the games, the listing to put in your computer 
and a sample run to show you how they work. Fun. Any 
one game will be worth more than the price of the book 
for the fun you and your family will have with it. $7.50.* 

• MORE BASIC COMPUTER GAMES — BK1 182 — 
edited by David H. Ahl. More fun in BASIC! 84 new 
games from the people who brought you BASIC Com- 
puter Games. Includes such favorites as Minotaur (bat- 
tle the mythical beast) and Eliza (unload your troubles 
on the doctor at bargain rates). Complete with game 
description, listing and sample run. $7.50.* 

• WHAT TO DO AFTER YOU HIT RETURN- BK1071 — 
PCC's first book of computer games. . .48 different 
computer games you can play in BASIC. . .programs, 
descriptions, many illustrations. Lunar Landing, Ham- 
murabi, King, Civel 2, Qubic 5, Taxman, Star Trek, 
Crash, Market, etc. $10.95.* 






X 



Mm 



ft 



• HOW TO MAKE MONEY WITH COMPUTERS - 
BK1003— In 10 information-packed chapters, Jerry 
Felsen describes more than 30 computer-related, 
money-making, high profit, low capital investment op- 
portunities. $15.00.* 

• HOW TO SELL ANYTHING TO ANYBODY— BK7306— 

According to The Guinness Book of World Records, the 
author, Joe Girard, is "the world's greatest salesman." 
This book reveals how he made a fortune— and how you 
can, too. $2.25.* 

• THE INCREDIBLE SECRET MONEY MACHINE- 
BK1178— by Don Lancaster. A different kind of "cook- 
book" from Don Lancaster. Want to slash taxes? Get 
free vacations? Win at investments? Make money from 
something that you like to do? You'll find this book 
essential to give you the key insider details of what is 
really involved in starting up your own money machine. 
$5.95.* 



*Use the order card in this magazine or itemize your order on a separate piece of 
paper and mail to Kilobaud Microcomputing Book Department • Peterborough NH 
03458. Be sure to include check or detailed credit card information. 



No COD. orders accepted. All orders add $1.50 for first book, $1.00 each addi- 
tional book, $10.00 per book foreign airmail. Please allow 4-6 weeks for delivery. 
Questions regarding your order? Please write to customer Service at the follow- 
ing address. 

PRICES SUBJECT TO CHANGE WITHOUT NOTICE 



FOR TOLL FREE ORDERING CALL 1-800-258-5473 



kb microcomputing book nook 



INTRODUCTORY 





• UNDERSTANDING AND PROGRAMMING MICRO- 
COMPUTERS— BK7382— A valuable addition to your 
computing library. This two-part text includes the best 
articles that have appeared in 73 and Kilobaud 
Microcomputing magazines on the hardware and soft- 
ware aspects of microcomputing. Well-known authors 
and well-structured text helps the reader get involved. 
$10.95* 

• SOME OF THE BEST FROM KILOBAUD MICROCOM- 
PUTING— BK731 1 —A collection of the best articles that 
have appeared in Kilobaud MICROCOMPUTING. Includ- 
ed is material on the TRS-80 and PET systems, CP/M, the 
8080/8085/Z-80 chips, the ASR-33 terminal. Data base 
management, word processing, text editors and file 
structures are covered too. Programming techniques 
and hard-core hardware construction projects for 
modems, high speed cassette interfaces and TVTs are 
also included in this large format, 200 plus page edition. 
$10.95.* _ 



• YOUR FIRST COMPUTER — BK1 191— by Rodnay 
Zaks. Whether you are using a computer, thinking 
about using one or considering purchasing one, this 
book is indispensable. It explains what a computer 
system is, what it can do, how it works and how to 
select various components and peripheral units. It is 
written in everyday language and contains invaluable 
information for the novice and the experienced pro- 
grammer. (The first edition of this book was published 
under the title "An Introduction to Personal and 
Business Computing") $8.95* 



•MICROPROCESSOR INTERFACING TECHNIQUES 

— BK1037— by Austin Lesea & Rodnay Zaks— will 
teach you how to interconnect a complete system and 
interface it to all the usual peripherals. It covers hard- 
ware and software skills and techniques, including the 
use and design of model buses such as the IEEE 488 or 
S-100. $17.95* 



• HOBBY COMPUTERS ARE HERE! — BK7322— If you 
want to come up to speed on how computers work . . . 
hardware and software. . .this is an excellent book. It 
starts with fundamentals and explains the circuits, and 
the basics of programming, along with a couple of TVT 
construction projects, ASCII-Baudot, etc. This book has 
the highest recommendations as a teaching aid. $4.95.* 

• THE NEW HOBBY COMPUTERS— BK7340— This 
book takes it from where "HOBBY COMPUTERS ARE 
HERE!" leaves off, with chapters on Large Scale Integra- 
tion, how to choose a microprocessor chip, an introduc- 
tion to programming, low cost I/O for a computer, com- 
puter arithmetic, checking memory boards... and 
much, much more! Don't miss this tremendous value! 
Only $4.95.* 

• AN INTRODUCTION TO MICROCOMPUTERS, VOL. 

— BK1130— The Beginner's Book— Written for readers 
who know nothing about computers— for those who 
have an interest in how to use computers— and for 
everyone else who must live with computers and 
should know a little about them. The first in a series of 
4 volumes, this book will explain how computers work 
and what they can do. Computers have become an in- 
tegral part of life and society. During any given day you 
are affected by computers, so start learning more 
about them with Volume 0. $7.95.* 

• VOL. I— BK1030— 2nd Edition completely revised. 
Dedicated to the basic concepts of microcomputers 
and hardware theory. The purpose of Volume I is to 
give you a thorough understanding of what microcom- 
puters are. From basic concepts (which are covered in 
detail), Volume I builds the necessary components of a 
microcomputer system. This book highlights the dif- 
ference between minicomputers and microcomputers. 
$12.99.* 

• VOL. II— BK1040 (with binder)— Contains descrip- 
tions of individual microprocessors and support 
devices used only with the parent microprocessor. 
Volume II describes all available chips. $31.99* 

• VOL. Ill— BK1133 (with binder)— Contains descrip- 
tions of all support devices that can be used with any 
microprocessor. $21.99* 



TR$-#Q Qr»phfe$ 



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• TRS-80 DISK AND OTHER MYSTERIES— BK1 181 — 

by Harvard C. Pennington. This is the definitive work 
on the TRS-80 disk system. It is full of detailed "How 
to" information with examples, samples and in-depth 
explanations suitable for beginners and professionals 
alike. The recovery of one lost file is worth the price 
alone. $22.50.* 



• MICROSOFT BASIC DECODED AND OTHER 
MYSTERIES— BK1 186— by James Farvour. From the 
company that brought you TRS-80 DISK AND OTHER 
MYSTERIES*. Contains more than 6500 lines of com- 
ments for the disassembled Level II ROMs, six addi- 
tional chapters describing every BASIC subroutine, 
with assembly language routines showing how to use 
them. Flowcharts for all major routines give the reader 
a real insight into how the interpreter works. $29.50. 



THE CUSTOM TRS-80 AND OTHER MYSTERIES— 

BK1218— by Dennis Kitsz. More than 300 pages of 
TRS-80 customizing information. With this book you'll 
be able to explore your computer like never before. 
Want to turn an 8 track into a mass storage unit? In- 
dividual reverse characters? Replace the BASIC 
ROMs? Make Music? High speed, reverse video, Level I 
and Level II? Fix it if it breaks down? All this and much, 
much more. Even if you have never used a soldering 
iron or read a circuit diagram, this book will teach you 
how! This is the definitive guide to customizing your 
80! $29.95.* 

• BASIC FASTER AND BETTER AND OTHER MYS- 
TERIES— BK1221— by Lewis Rosenfelder. You don't 
have to learn assembly language to make your pro- 
grams run fast. With the dozens of programming tricks 
and techniques in this book you can sort at high speed, 
swap screens in the twinkling of an eye, write INKEY 
routines that people think are in assembly language 
and add your own commands to BASIC. Find out how 
to write elegant code that makes your BASIC really 
hum, and explore the power of USR calls. $29.95.* 

• THE CP/M HANDBOOK (with MP/M)— BK1187— by 
Rodnay Zaks. A complete guide and reference hand- 
book for CP/M— the industry standard in operating 
systems. Step-by-step instruction for everything from 
turning on the system and inserting the diskette to cor- 
rect user discipline and remedial action for problem 
situations. This also includes a complete discussion 
of all versions of CP/M up to and including 2.2, MP/M 
and CDOS. $14.95*. 

• INTRODUCTION TO TRS-80 GRAPHICS— BK1 180— 
by Don Inman. Dissatisfied with your Level I or Level II 
manual's coverage of graphics capabilities? This well- 
structured book (suitable for classroom use) is ideal 
for those who want to use all thegraphics capabilities 
built into the TRS-80. A tutorial method is used with 
many demonstrations. It is based on the Level I, but all 
material is suitable for Level II use. $8.95.* 



• TOOLS & TECHNIQUES FOR ELECTRONICS— 

BK7348— by A. A. Wicks is an easy-to-understand book 
written for the beginning kit builder as well as the ex- 
perienced hobbyist. It has numerous pictures and 
descriptions of the safe and correct ways to use basic 
and specialized tools for electronic projects as well as 
specialized metal working tools and the chemical aids 
which are used in repair shops. $4.95.* 

• HOW TO BUILD A MICROCOMPUTER— AND REALLY 
UNDERSTAND IT— BK7325— by Sam Creason. The elec- 
tronics hobbyist who wants to build his own microcom- 

?uter system now has a practical "How-To" guidebook, 
his book is a combination technical manual and pro- 
gramming guide that takes the hobbyist step-by-step 
through the design, construction, testing and debugging 
of a complete microcomputer system. Must reading for 
anyone desiring a true understanding of small computer 
systems. $9.95.* 



*Use the order card in this magazine or itemize your order on a separate piece of 
paper and mail to Kilobaud Microcomputing Book Department • Peterborough NH 
03458. Be sure to include check or detailed credit card information. 



No COD. orders accepted. All orders add $1.50 for first book, $1.00 each addi- 
tional book, $10.00 per book foreign airmail. Please allow 4-6 weeks for delivery. 
Questions regarding your order? Please write to customer Service at the follow- 
ing address. 



PRICES SUBJECT TO CHANGE WITHOUT NOTICE 




FOR TOLL FREE ORDERING CALL 1-800-258-5473 




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192 Microcomputing, December 1981 



FULL LINE ALL PARTS & COMPUTER PRODUCTS 



ELECTRONICS 



^44 P.O. Box 4430S 

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7445N 

7447N 

7448N 

74SOM 

7474N 

7475N 

7485N 

7489N 

7490N 

7492N 

7493N 

7495N 

7410ON 

74107N 

74121N 

74123N 

7412SN 

74145N 

741SON 

74151N 

74154N 

74157N 

74161N 

74162N 

74163N 

741 74N 

741 75N 

741 90N 

74182N 

74193N 

74221 N 

742MN 

7436SN 

74366N 

74367N 

74LSO0TTL 

74LSOON 

74LS02N 

74LS04N 

74LS05N 

74LS06N 

74LS10N 

74LS13M 

74LS14N 

74LS20N 

74LS22N 

74LS2SN 

74LS30N 

74LS33N 

74LS38N 

74LS74N 

74LS75N 

74LS90N 

74LS93N 

74LS95N 

74LS107N 

74LS112N 

74LS113N 

74LS132N 

74LS136N 

74LS1S1N 

74LS155N 

74LS157N 

74LS162N 

74LS163N 

74LS174N 

74LS190N 

74LS221N ' 

74LS258N 

741S387N 



CA3045 90 

CA3046 1 10 

CA3081 1 80 

CA3082 190 
CA3089 3 40 
LM301AN.AH 34 



LM30SH 

LM307N 

LM308N 

LM309K 

LM311H/N 

LM3177 

LM317K 

\.»«16 

LM320K5 

LM320K 12 

LM320K-15 

LM320T5 

LM320T8 

LM320T12 

IM320T-15 

LM323K-5 

LM324N 

LM339N 

LM340K5 

LM340K-8 

LM340K-12 

LM340K IS 

LM340K-24 

LM340T-5 

LM340T-8 

LM340T-12 

IM340T-15 

LM340T-18 

LM340T-24 

LM350 

LM377 

LM379 

LM380N 

LM381 

LM382 

LM709H 

LM723H N 

LM733N 

LM741CH 

LM741N 

LM747H/N 

LM748N 

LM1303N 

LM1304 

LM130S 

LM1307 

LM1310 

LM14S8 

LM1812 

LM1889 

LM2111 

LM2902 

IM3900N 

LM390S 

LM3909M 

MC 1458V 

NE550N 

NE555V 

NE556A 

NE565A 

NE566V 

NE567V 

NE570B 

78L05 

78L08 

78M05 

75108 

75491 CN 

75492CN 

75494CN 



A 10 D CONVERTS 



8038B 

8700CJ 

8701CN 

8750CJ 

LD130 

9400CJV/F 

ICL7103 

ICL7107 

CMOS 

CD4000 
C04001 
C04002 
CD4006 
C04007 
CD4008 
CD4009 
C04010 



450 
13 95 
22 00 

13 95 
9 95 
740 
950 

14 25 



C04011 
C04012 
C04013 
CD4014 
CO4015 
C04016 
C04017 
CD401B 
> CD4019 
i C04020 
i C04021 
C04022 
C04023 
C04024 
CO4025 
CD4026 
CD4027 
C04028 
C04029 
C04030 
CD4035 
C04O40 
C04042 
C04043 
CD4044 
CD4046 
C04049 
C04050 
C04051 
CO4060 
CD4066 
C04068 
C04069 
CD4O70 
C04071 
CD4072 
CD4073 
CO4075 
C04076 
CD4078 
C04081 
CD4082 
CD4116 
C04490 
CD4507 
C04508 
CD4510 
C04511 
CD4515 
CD4516 
CD4518 
CU4520 
CD4527 
CD4528 
CD4553 
C04566 
C04583 
C0458S 
CD40192 
74CO0 
74C04 
74C10 
74C14 
74C20 
74C30 
74C48 
74C74 
74C76 
74C90 
74C93 
74C154 
74C160 
74C175 
74C192 
74C221 
74C905 
74C906 
74C914 
74C922 
74C923 
74C925 
74C926 
74C927 

INTERFACE 

8095 
8096 
8097 
8096 
8T09 



8T10 1 

8T13 1 

8T20 4 

8T23 1 

8T24 1 

8T25 3 

8T26 1 

8T28 1 
8T97 

8T98 1 

MOS MEMORY 
RAM 

2101-1 1 
21021 

2102AL-4 1 

2102AN-2L 1 

2104A-4 4 

2107B-4 3 

2111-1 2 

2112-2 2 

2114 2 

21141300ns 4 

21 141 450ns 2 

4116 200ns 2 
8<4116 200ns16 95 



MM5262 

MMS280 

MM5320 

MM5330 

P04110-3 

P04110-4 

P5101L 

4200A 

82S25 

9 1102 A 

MM5710O 

GIAY38500-1 

9368 

4100 

416 

CLOCKS 
MM5311 
MM5312 
MM5314 
MM5369 
MM5841 

MMdODD 

CT7010 
CT7015 
MM5375AAN 3 90 
MM5375AG.N 4 90 



40 

300 

995 

594 

400 

500 

895 

11 50 

290 

1 50 

450 

995 

350 

10 00 

16 00 



4 95 
390 
390 
1 95 
1445 

7 95 
895 

8 95 



UART'FIFO 

AY5 1013 
AY5 1014 
3341 

PROM 

1702A 

2532 

2708 

2716TI 

2716 5 Volt 

8/2716 5 Volt 

2732 

2758 

8741 A 

8748 

8748-8 

8755A 

N82S23 

N82S123 

N82S126 

N82S129 

N82S131 

N82S136 

N82S137 

DM8577 

8223 

CONNECTORS 

30 pin edge 
44 pin edge 

86 pin edge 
100 pin edge 



550 
750 
695 



7205 

7207 

7208 

7209 

DS0026CN 

DS0056CN 

MM53104 



16 50 
750 

15 95 
4 95 
3 75 
375 
250 



MICROPROCESSOR 

6502 6 95 

6504 6 95 

6522 9 95 

6530 9 50 

6800 695 

6802 11 95 

6820 4 95 

6850 4 75 

8080A 3 95 

8085 8 50 

Z80 8 95 

Z80A 9 95 

8212 2 25 

8214 390 

8216 225 

8224 2 50 

8228 4 95 

8251 5 50 

8253 8 95 

8255 5 25 

8257 9 00 

8259 9 95 
1802CE Was 13 95 
1802F plas 17 95 

1861P 9 50 



450 
19 75 
395 
850 
595 
46 95 
16 50 

7 49 
39 95 
55 00 
55 00 
49 95 

295 
395 
575 
4 75 
495 

8 75 
8 75 
290 
350 

250 
2 75 
400 
395 
100 pin edge w/w 4 95 

IC SOCKETS 

Solder Tin Low Profile 

PIN 1UP PIN 1UP 

8 13 22 30 

14 14 24 30 

16 16 28 40 

18 20 36 58 

20 29 40 49 

WIRE WRAP LEVEL 3 
PIN PIN 

14 55 24 93 
16 57 28 1 00 

18 67 40 1 59 

2 level 14 pin ww 20 

CRYSTALS 

1 MH; 4 50 

2 MH2 4 50 

4 MHz 4 25 

5 MHz 4 25 
10 MH2 4 25 
18 MHz 3 90 
20 MH2 3 90 
32 MHz 3 90 
32768 Hi 4 00 

1 8432 MHz 4 50 
3 5795 MHz 1 20 

2 0100 MHz 1 95 
2 097152 MHz 4 50 

2 4576 MHz 4 SO 

3 2768 MHz 4 SO 
S 0688 MHz 4 SO 
5 185 MHz 4 SO 

5 7143 MHz 4 SO 

6 SS36 MHz 4 SO 
14 31818 MHz 4 25 
18 432 MHz 4 SO 
22 1184 MHz 4 SO 

KEYBOARD ENCOOERS 

AY5-2376 11 95 

AY5 3600 17 95 

AY5 9100 10 50 

AY5 9200 14 95 

74C922 5 49 

74C923 5 SO 

HD0165 5 7 95 

Connectors RS232 
OB25P 2 95 

DB2SS 3 50 

Cover 1 67 



0£9S 


1 95 


OA15P 


2 10 


DA1SS 


3 10 


Complete Set 


9 SO 


Suiwatck Kll 


26 95 


Auto Clock Kit 


17 95 


Digital Clock Kll 19 75 


RESISTORS ' « watt 5% 


10 per type 


03 


25 per type 


025 


100 per type 


015 


1000 per type 


012 


350 piece pack 




S per type 


6 75 



' i watt 1% per type 05 

DIP SWITCHES 

4 position 85 

5 position 90 

6 position 90 

7 position 95 

8 position 95 

KEYBOARDS 

56 key ASCII keyboard kit 
Fully assembled 

Enclosure Plastic 

Metal Enclosure 



$74 95 
84 50 
94 95 
39 95 



LEOS 

RedTOIS 15 

Green. Yellow T01 8 20 

Jumbo Red .25 

Green. Orange. Yellow Jumbo 25 

CHpllU LED Mouirllng Clip* 8 SI 25 
(spec red. amber, green yellow clean 

CONTINENTAL SPECIALTIES in slock 

Complete line ot breadboard test equip 

OK WIRE WRAP TOOLS In Mick 

Complete line ol AP Products in stock 

SPECIAL PRODUCTS 

2 5 MHz Freq Counter Kit 37 50 
30 MHz Freq Counter Kit 47 75 

TRANSFORMERS 

6V 300 ma 3 25 

12 Volt 300 ma transformer 1 25 

12 6V CT 600 ma 3 75 

12V 250 ma wall plug 2 95 

12V CT 250 ma wall plug 3.75 

24V CT 100 ma 3 95 

10V 1 2 amp wall plug 4 85 

12V 6 amp 12 95 

12V 500 ma wall plug 4 75 

12V 1 amp wall plug 6 50 

10/15 VAC 8/16 VA wall plug 9 75 

DISPLAY LEOS 

MAN1 CA 270 2 90 

MAN3 CC 125 25 

MAN7274 CA/CA 300 75 

0L704 CC 300 1 25 

DL707-OL707R CA 300 1 00 

OL727 728 CA CC 500 1 90 

DL747 750 CACC 600 1 49 

FND359 CC 357 70 

F NO 500 507 CC CA 500 99 

FN0503/510 CC CA 500 90 

FN0800B07 CC CA 800 2 20 

3 digit bubble 60 
10 digit display 1 25 
7520 Clairex photocells 39 
TIL311 Hex 9 50 
MAN3640 CC 30 99 
MAN4610 CA 40 99 
MAN4640 CC 40 1 20 
MAN4710 CA 40 95 
MAN4740 CC 40 1 20 
MAN6640 CC 56 99 
MAN6710 CA 60 99 
MAN6740 CC 60 99 



TELEVIDEO TERMINAL 

Model 950 



$1010 00 



4116 200ns Dynamic RAM 8 $16.95 



ELECTRONIC SYSTEM KITS 

Apple Peripheral Kits 

SERIAL I/O INTERFACE to 30,000 baud, 
D.T.R.. Input & output from monitor or basic, or 
use Apple as intelligent terminal, Bd only (P/N 2) 
$14.95, Kit (P/N 2A) $51.25, Assembled (P/N 
2C) $62.95. 

PROTOTYPING BOARD (P/N 7907) $21.95. 
PARALLEL TRIAC OUTPUT BOARD 8 triacs, 
each can switch 110V. 6A loads, Bd only (P/N 
210) $19.20, Kit (P/N 210A) $119.55. 
OPTO-ISOLATED INPUT BOARD 8 inputs, can 
be driven from TTL logic, Bd only (P/N 120) 
$15.65, Kit (P/N 120A) $69.95. 

Interface Kits 

SERIAL/PARALLEL INTERFACE Bidirectional, 
Baud rates from 110 to 19. 2K, sw selectable 
polarity of input and output strobe, 5 to 8 data 
bits, 1 or 2 stop bits, parity odd or even or none, 
all characters contain a start bit, +5 & -12V 
required. Bd only (P/N 101) $11.95, Kit (P/N 
101A) $42.89. 

RS-232/TTL INTERFACE Bidirectional, re- 
quires ±12V. Kit (P/N 232A) $9.95. 
RS-232/20mA INTERFACE Bidirectional. 2 
passive opto-isolated circuits. Kit (P/N 7901A) 
$14.95. 

PROM Eraser 

Will erase 25 PROMs in 15 minutes. Ultraviolet, 
assembled. 25 PROM capacity $37.50 (with 
timer $69.50). 6 PROM capacity OSMA/UL ver- 
sion $78.50 (with timer $108.50). 

NiCad Battery Fixer/Charger Kit 

Opens shorted cells that won't hold a charge and 
then charges them up. all in one kit w/full parts 
and instructions. $9.95 



Z80 Microcomputer 

16 bit 1/0. 2 MHz clock, 2K RAM, ROM Bread- 
board space. Excellent for control. Bare Board 
$28.50. Full Kit $99.00. Monitor $20.00. Power 
Supply Kit $35.00. Tiny Basic $30.00. 

Modem Kit $60.00 

State of the art, orig., answer. No tuning neces- 
sary. 103 compatible 300 baud. Inexpensive 
acoustic coupler plans included. Bd. only 
$17.00 Article in June Radio Electronics. 

60 Hz Crystal Time Base Kit $4.40 

Converts digital clocks from AC line frequency to 
crystal time base. Outstanding accuracy. 

Video Modulator Kit $9.95 

Convert TV set into a high quality monitor w/o 
affecting usage. Comp. kit w/full instruc. 

Rockwell AIM 65 Computer 

6502 based single board with full ASCII keyboard 
and 20 column thermal printer. 20 char, alphanu- 
meric display ROM monitor;, fully expandable 
$419.00. 4K version $449.00 4K Assembler 
$35.00, 8K Basic Interpreter $65.00 

Special small power supply 5V 2 A 24V 5A 
assem. in frame $59.00. Molded plastic 
enclosure to fit both AIM 65 and power supply 
$52.50. AIM 65 1K in cabinet with power supply, 
switch, fuse, cord assem $559.00. 4K $579.00. 
A65 40 5000 AIM 65/40 w 16K RAM and monitor 
$1295.00. RAM Board Kit (16K, $195) (32K, 
$215) VD640 Video Interface Kit $119.00. A&T 
$149.00. Complete AIM 65 in thin briefcase with 
power supply $518.00. Special Package Price: 4K 
AIM, 8K Basic, power supply, cabinet $629.00 

AIM 65/KIM/SYM/Super Elf 44 pin expansion 
board; board with 3 connectors $22.95. 






'. .i?* 



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RCA Cosmac 1802 Super Elf Computer $106.95 



The Super Elf is a small single board computer that 
does many big things. It's an excellent computer 
for training and for learning programming with its 
machine language and yet it's easily expanded 
with additional memory, Full Basic, ASCII 
Keyboards, video character generation, etc. 

ROM monitor; State and Mode displays; Single 
step; Optional address displays; Power Supply; 
Audio Amplifier and Speaker; Fully socketed for all 
IC's; Full documentation. 

The Super EH includes a ROM monitor for pro- 
gram loading, editing and execution with SINGLE 
STEP for program debugging which is not in- 
cluded in others at the same price. With SINGLE 
STEP you can see the microprocessor chip oper- 
ating with the unique Quest address and data bus 
displays before, during and after executing in- 
structions. Also, CPU mode and instruction cycle 
are decoded and displayed on 8 LED indicators. 

An RCA 1861 video graphics chip allows you to 
connect to your own TV with an inexpensive video 
modulator to do graphics and games. There is a 
speaker system included for writing your own 
music or using many music programs already 
written. The speaker amplifier may also be used to 
drive relays for control purposes 

A 24 key HEX keyboard includes 16 HEX keys plus 
load, reset, run, wait, input, memory protect, 
monitor select and single step Large, on board 
displays provide output and optional high and low 
address There is a 44 pin standard connector slot 



for PC cards and a 50 pin connector slot for the 
Quest Super Expansion Board. Power supply and 
sockets for all IC's are included plus a detailed 
127 pg. instruction manual which now includes 
over 40 pgs. of software info, including a series of 
lessons to help get you started and a music pro- 
gram and graphics target game. Many schools 
and universities are using the Super Elf as a 
course of study OEM's use it for training and 
R&O. 

Remember, other computers only offer Super Elf 
features at additional cost or not at all. Compare 
before you buy. Super Elf Kit $106.95, High 
address option $8.95, Low address option 
$9.95. Custom Cabinet with drilled and labelled 
plexiglass front panel $24.95. All metal Expansion 
Cabinet, painted and silk screened, with room for 
5S-100 boards and power supply $57.00. NiCad 
Battery Memory Saver Kit $6.95. All kits and 
options also completely assembled and tested. 

Questdata, a software publication for 1802 com- 
puter users is available by subscription for $12.00 
per 12 issues. Single issues $1.50. Issues 1-12 
bound $16.50. 

Moews Video Graphics $3.50, Games and Music 
$3.00, Chip 8 Interpreter $5.50, Starship 4K cas- 
sette $14.95. 

Free 14 page brochure 

of complete Super Elf system. 



Super Expansion Board with Cassette Interface $89.95 



This is truly an astounding value! This board has 
been designed to allow you to decide how you 
want it optioned The Super Expansion Board 
comes with 4K of low power RAM fully address- 
able anywhere in 64K with built-in memory pro- 
tect and a cassette interface. Provisions have 
been made for all other options on the same board 
and it fits neatly into the hardwood cabinet 
alongside the Super Elf. The board includes slots 
for up to 6K of EPROM (2708, 2758, 2716 or Tl 
2716) and is fully socketed. EPROM can be used 
for the monitor and Tiny Basic or other purposes. 

A 1K Super ROM Monitor $19.95 is available as an 
on board option in 2708 EPROM which has been 
preprogrammed with a program loader/editor and 
error checking multi file cassette read/write 
software, (relocatable cassette file) another exclu- 
sive from Quest. It includes register save and 
readout, block move capability and video graphics 
driver with blinking cursor. Break points can be 
used with the register save feature to isolate pro- 



gram bugs quickly, then follow with single step. If 
you have the Super Expansion Board and Super 
Monitor the monitor is up and running at the push 
of a button. 

Other on board options include Parallel Input and 
Output Ports with full handshake They allow easy 
connection of an ASCII keyboard to the input port. 
RS 232 and 20 ma Current Loop for teletype or 
other device are on board and if you need more 
memory there are two S-100 slots for static RAM 
or video boards. Also a 1K Super Monitor version 
2 with video driver for full capability display with 
Tiny Basic and a video interface board. Parallel 
1/0 Ports $9.85, RS 232 $4.50, TTY 20 ma l/F 
$1.95, S-100 $4.50. A 50 pin connector set with 
ribbon cable is available at $15.25 for easy con- 
nection between the Super Elf and the Super 
Expansion Board. 

Power Supply Kit for the complete system (see 
Multi-volt Power Supply below). 



Quest Super Basic V5.0 

A new enhanced version of Super Basic now 
available. Quest was the first company worldwide 
to ship a full size Basic for 1802 Systems. A 
complete function Super Basic by Ron Cenker 
including floating point capability with scientific 
notation (number range ±.17E M ), 32 bit integer 
±2 billion; multi dim arrays, string arrays; string 
manipulation; cassette I/O; save and load, basic, 
data and machine language programs; and over 
75 statements, functions and operations. 
New improved faster version including re- 
number and essentially unlimited variables 
Also, an exclusive user expandable command 
library 

Senal and Parallel I/O routines included 
Super Basic on Cassette $55.00. 



Type-N-Talk by Votrax 

Text to speech synthesizer with unlimited vocabu- 
lary, built-in text to speech algorithm. 70 to 100 
bits per second speech synthesizer, RS232C 
interface $369.00. 



1802 16K Dynamic RAM Kit $149.00 

Expandable to 64K. Hidden refresh w/ctocks up to 
4 MHz w/no wait states. Addl. 16K RAM $25.00. 
S-100 4-slot expansion $ 9.95 

Super Monitor VI. I Source Listing $15.00 



Super Color S-100 Video Kit $129.95 

Expandable to 256 x 192 high resolution color 
graphics. 6847 with all display modes computer 
controlled. Memory mapped. 1K RAM expand- 
able to 6K. S-100 bus 1802. 8080. 8085. Z80, 
etc Dealers: Send for excellent pricing/margin 
program. 



Multi-volt Computer Power Supply 

8v 5 amp, ±18v .5 amp, 5v 1.5 amp. -5v 
5 amp, 12v 5 amp, -12v option. ±5v, ±12v 
are regulated. Basic Kit $35.95. Kit with chassis 
and all hardware $51.95. Add 55.00 shipping. Kit 
of hardware $16.00. Woodgrain case $10.00. 
$1.50 shipping. 



Elf II Adapter Kit $24.95 

Plugs into Elf II providing Super Elf 44 and 50 pin 
plus S-100 bus expansion. (With Super Ex- 
pansion). High and low address displays, state 
and mode LED s optional $18.00. 



TERMS: $5.00 min. order U.S. Funds. Calif, residents add 6% tax. 

$10.00 min. VISA and MasterCard accepted. $1.00 insurance optional. 
Shipping: Add 5%; orders under $25.00 — 10%. 



FREE: Send for your copy of our NEW 1981 
QUEST CATALOG. Include 88c stamp. 



^See List of Advertisers on page 210 



Microcomputing, December 1981 193 



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DIGITAL RESEARCH COMPUTERS 

(214) 271-3538 



32K S-100 EPROM CARD 
NEW! 




$79.95 



USES 2716s 

Blank PC Board - $34 

ASSEMBLED & TESTED 
ADD $30 

SPECIAL: 2716 EPROM s (450 NS) Are $9.95 Ea. With Above Kit. 



KIT FEATURES: 

1 Uses +5V only 2716 (2Kx8) EPROMs 

2 Allows up to 32K of software on line' 

3 IEEE S-100 Compatible 

4 Addressable as two independent 16K 
blocks 

5. Cromemco extended or Northstar bank 

select 
6 On board wait state circuitry if needed 



7 Any or all EPROM locations can be 
disabled 

8 Double sided PC board, solder-masked, 
silk-screened 

9 Gold plated contact fingers 

10 Unselected EPROMs automatically 
powered down for low power 

11 Fully buffered and bypassed. 

12 Easy and quick to assemble 



32K SS-50 RAM 



$299 



For 2MHZ 
Add $10 



Jlllftlti IlltaSlil 

liiiiii mtiiiiiR 



Blank PC Board 
$50 



■W KHMUH 



For SVVTPC 
6800 - 6809 Buss 



Support IC's 

and Caps 

$19.95 

Complete Socket Set 

$21.00 



Fully Assembled, 

Tested, Burned In 

Add $30 



At Last! An affordable 32K Static RAM with full 
6809 Capability. 

FEATURES: 

1. Uses proven low power 2114 Static RAMS. 

2. Supports SS50C - EXTENDED ADDRESSING. 

3. All parts and sockets included. 

4. Dip Switch address select as a 32K block. 

5. Extended addressing can be disabled. 

6. Works with all existing 6800 SS50 systems. 

7. Fully bypassed. PC Board is double sided, 
plated thru, with silk screen. 



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16K STATIC RAM KIT-S 100 BUSS 



PRICE CUT! 



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I II II Hill II 1 1 tl 
■ lliiiii 



16K STATIC RAM SS-50 BUSS 

PRICE CUT! 



~<3CV»» 






' t I I I I I II I I I III 1 I III I I I I I 



BLANK PC BOARD W/DATA-$33 

LOW PROFILE SOCKET SET-$12 

SUPPORT IC'S & CAPS-$19.95 



KIT FEATURES: - - 

1 Addressable as four separate 4K Blocks 

2 ON BOARD BANK SELECT circuitry (Cro- 
memco Standard') Allows up to 512K on line' 

3 Uses 2114 (450NS) 4K Static Rams 

4 ON BOARD SELECTABLE WAIT STATES 

5 Double sided PC Board, with solder mask and 
silk screened layout Gold plated contact fingers 

6 All address and data lines fully buffered ASSEMBLED & TESTED-ADD $35 
7. Kit includes ALL parts and sockets 

8 PHANTOM is jumpered to PIN 67 

9 LOW POWER: under 15 amps TYPICAL from 
the +8 Volt Buss 

10 Blank PC Board can be populated as any 
multiple of 4K 




FULLY STATIC! 



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iiiiiiiiiiinii 

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FOR 2MHZ 
ADD $10 






■«*r»¥ w 



FOR SWTPC 
6800 BUSS! 



OUR #1 SELLING 
RAM BOARD! 



H e** STEREO! *e», 

S-100 SOUND COMPUTER BOARD 



COMPLETE KIT! 
$g495 

(WITH DATA MANUAL) 



At last, an S-100 Board that unleashes the full power of two 
unbelievable General I nstrumentsAY3-8910NMOS computer 

sound IC's Allows you under total computer control to 

generate an infinite number of special sound effects for 

games or any other program Sounds can be called in BASIC. 

ASSEMBLY LANGUAGE, etc 

KIT FEATURES: 

* TWO Gl SOUND COMPUTER IC'S. 

FOUR PARALLEL I/O PORTS ON BOARD 

USES ON BOARD AUDIO AMPS OR YOUR STEREO 

ON BOARD PROTO TYPING AREA 

ALL SOCKETS. PARTS AND HARDWARE ARE INCLUDED 

PC BOARD IS SOLDERMASKED. SILK SCREENED. WITH GOLD CONTACTS 

EASY QUICK. AND FUN TO BUILD WITH FULL INSTRUCTIONS 

USES PROGRAMMED I/O FOR MAXIMUM SYSTEM FLEXIBILITY. 

Botn Basic and Assembly Language Programming examples are included 

SOFTWARE: 

SCL" is now available! Our Sound Command Language makes writing Sound Effects programs 
a SNAP! SCL'" also includes routines for Register-Examine-Modify, Memory-Examine-Modify. 
and Play-Memory. SCL™ is available on CP/M* compatible diskette or 2708 or 2716 Diskette - 
$24.95 2708 - $19.95 2716 - $29.95. Diskette includes the source EPROMS are ORG at 
E000H (Diskette is 8 Inch Soft Sectored) 



* 
* 



BLANK PC 

BOARD W/DATA 

$31 



ASSEMBLED AND 
TESTED - $35 



KIT FEATURES 

1 Addressable on 16K Boundaries 

2 Uses 2114 Static Ram 

3 Fully Bypassed 

4 Double sided PC Board Solder mask 
and silk screened layout 

5 ^'l Parts and Sockets included 

6 Low Powei Under 1 5 Amps Typical 



BLANK PC BOARD— $35 COMPLETE SOCKET SET— $12 

SUPPORT IC'S AND CAPS— $19.95 



SPECIAL PURCHASE! 

UART SALE! 

TR1 602B — SAME AS TMS601 1 , 
AY5-1 01 3, ETC. 40 PIN DIP 



TR1602B 



EACH 



4For $ 10 



CRT CONTROLLER CHIP 
SMC #CRT 5037. PROGRAMMABLE FOR 80 x 24, ETC. VERY RARE 
SURPLUS FIND. WITH PIN OUT. $12.95 EACH. 



4K STATIC RAM 

National Semi. MM5257. Arranged 4K x 1. +5V, 18 PIN DIP. A 
Lower Power, Plug in Replacement for TMS 4044. 450 NS. 
Several Boards on the Market Will Accept These Rams. SUPER 
SURPLUS PURCHASE! PRIME NEW UNITS! 

8 FOR $16 32 FOR $59.95 



NEW! G.I. COMPUTER SOUND CHIP 

AY3-8910 As featured in July. 1979 BYTE 1 A fantastically powerful Sound & Music 
Generator Perfect for use with any 8 Bit Microprocessor Contains 3 Tone Channels 
Noise Generator. 3 Channels of Amplitude Control 16 bit Envelope Period Control. 2-8 
Bit Parallel I/O 3 D to A Converters plus much more' All in one 40 Pin DIP Super easy 
interface to the S-100 or other busses $11.95 PRICE CUT! 

SPECIAL OFFER: »*4^5 each Add $3 for 60 page Data Manual. 



Digital Research Computers 

^ (OF TEXAS) ■ 

P.O. BOX 401565 • GARLAND, TEXAS 75040 • (214) 271-3538 



TERMS: Add $2.00 postage. We pay balance Orders under $15 add 75C 
handling. No C.O.D. We accept Visa and MasterCharge. Tex. Res. add 5% 
Tax. Foreign orders (except Canada) add 20% P & H. Orders over $50, add 
85C for insurance. 



•TRADEMARK OF DIGITAL RESEARCH. 



WE ARE NOT ASSOCIATED WITH DIGITAL RESEARCH OF CALIFORNIA, THE SUPPLIERS OF CPM SOFTWARE. 




"THE BIG BOARD" 

OEM - INDUSTRIAL - BUSINESS - SCIENTIFIC 

SINGLE BOARD COMPUTER KIT! 

Z-80 CPU! 64K RAM! 




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THE FERGUSON PROJECT: Three years in the works, and maybe too good to be true. A tribute to hard headed, 
no compromise, high performance, American engineering! The Big Board gives you all the most needed 
computing features on one board at a very reasonable cost. The Big Board was designed from scratch to run the 
latest version of CP/M*. Just imagine all the off-the-shelf software that can be run on the Big Board without any 
modifications needed! Take a Big Board, add a couple of 8 inch disc drives, power supply, an enclosure, C.R.T., 
and you have a total Business System for about 1/3 the cost you might expect to pay. 



$ 649 



(64K KIT 
BASIC I/O) 



FULLY SOCKETED! 



FEATURES: (Remember, all this on one board!) 



SIZE: 8V» x 13 3 /« IN. 
SAME AS AN 8 IN. DRIVE. 
REQUIRES: • 5V @ 3 AMPS 
♦ - 12V @ .5 AMPS. 



64K RAM 



24 x 80 CHARACTER VIDEO 



Uses industry standard 4116 RAM'S. All 64K is available to the user, our VIDEO 
and EPROM sections do not make holes in system RAM. Also, very special care 
was taken in the RAM array PC layout to eliminate potential noise and glitches. 



Z-80 CPU 



With a crisp, flicker-free display that looks extremely sharp even on small 
monitors. Hardware scroll and full cursor control. Composite video or split video 
and sync. Character set is supplied on a 2716 style ROM, making customized 
fonts easy. Sync pulses can be any desired length or polarity. Video may be 
inverted or true. 5x7 Matrix - Upper & Lower Case 



Running at 2.5 MHZ. Handles all 4116 RAM refresh and supports Mode 2 
INTERUPTS. Fully buffered and runs 8080 software. 



FLOPPY DISC CONTROLLER 



SERIAL I/O (OPTIONAL) 



Full 2 channels using the Z80 SIO and the SMC 81 16 Baud Rate Generator. FULL 
RS232! For synchronous or asynchronous communication. In synchronous 
mode, the clocks can be transmitted or received by a modem. Both channels can 
be set up for either data-communication or data-terminals. Supports mode 2 Int. 
Price for all parts and connectors: $85. 



Uses WD1771 controller chip with a TTL Data Separator for enhanced 
reliability. IBM 3740 compatible. Supports up to four 8 inch disc drives. Directly 
compatible with standard Shugart drives such as the SA800 or SA801 . Drives can 
be configured for remote AC off-on. Runs CP/M* 2.2. 



TWO PORT PARALLEL I/O (OPTIONAL) 



Uses Z-80 PIO. Full 16 bits, fully buffered, bi-directional. User selectable hand 
shake polarity. Set of all parts and connectors for parallel I/O: $29.95 



BASIC I/O 



Consists of a separate parallel port (Z80 PIO) for use with an ASCII encoded 
keyboard lot input. Output would be on the 80 x 24 Video Display. 



REAL TIME CLOCK (OPTIONAL) 



Uses Z-80 CTC. Can be configured as a Counter on Real Time Clock. Set of all 
parte: $14.95 



SYSTEM COMPARISON 



64K RAM KIT 

80 x 24 Video Kit 

Floppy Disk Controller Kit 

Z-80 CPU Kit 

SER & PAR. I/O 

S-100 Mother Board 

SUB TOTAL 



$370.00 
365.00 
. 235.00 
.. 185.95 
.. 129.95 
... 45.00 
$1330.90 



Talk about bangs per buck! The prices shown for 
S100 kits were taken from the July 1980 BYTE. 
This will give some basis for comparison between 
the Big Board and a similar system implementa- 
tion on the S100 Buss. 



CP/M* 2.2 FOR BIG BOARD 



The popular CP/M* D.O.S. modified by MICRONIX 
SYSTEMS to run on Big Board is available for $150.00. 



PC BOARD 



Blank PC Board with Rom Set and Full Documentation. 

$199.00 



PFM 3.0 2K SYSTEM MONITOR 



The real power of the Big Board lies in its PFM 3.0 on board monitor. PFM commands include: Dump Memory, Boot CP/M*, Copy, Examine. Fill Memory. Test Memory, Go To. 
Read and Write I/O Ports, Disc Read (Drive, Track, Sector), and Search. PFM occupies one of the four 2716 EPROM locations provided. 
Z-80 is a Trademark of Zilog. 



Digital Research Computers 

w (OF TEXAS) r 

P.O. BOX 401565 • GARLAND, TEXAS 75040 • (214) 271-3538 



TERMS: Shipments will be made approximately 3 to 6 weeks after we 
receive your order. VISA. MC, cash accepted. We will accept COD's (for the 
Big Board only) with a $75 deposit. Balance UPS COD. Add $3.00shipping 

USA AND CANADA ONLY 



TRADEMARK OF DIGITAL RESEARCH. 



NOT ASSOCIATED WITH DIGITAL RESEARCH OF CALIFORNIA, THE ORIGINATORS OF CPM SOFTWARE 
**1 TO 4 PIECE DOMESTIC USA PRICE. 



64K S100 STATIC RAM 




$ 4999,° 







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...-..--.-- -».-.. 






»»*«.««««»« «»»»»«# w « W | > n 




BLANK PC BOARD 

WITH DOCUMENTATION 

$55 



SUPPORT ICs + CAPS - $17.50 
FULL SOCKET SET - $14.50 



ASSEMBLED AND TESTED ADD $40 



* 
• 
* 

• 
• 
• 



FULLY SUPPORTS THE NEW 

IEEE 696 S100 STANDARD 

(AS PROPOSED) 



FEATURES: 

* Uses new 2K x 8 (TMM 2016 or HM 6116) RAMs. 
Fully supports IEEE 696 24 BIT Extended Addressing. 
64K draws only approximately 500 MA. 

200 NS RAMs are standard. (TOSHIBA makes TMM 2016s as fast as 100 NS. FOR YOUR 
HIGH SPEED APPLICATIONS.) 

SUPPORTS PHANTOM (BOTH LOWER 32K AND ENTIRE BOARD). 
2716 EPROMs may be installed in any of top 48K. 

Any of the top 8K (E000 H AND ABOVE) may be disabled to provide windows to eliminate any 
possible conflicts with your system monitor, disk controller, etc. 

Perfect for small systems since BOTH RAM and EPROM may co-exist on the same board. 
BOARD may be partially populated as 56K. 



16K STATIC RAMS? 



FOR 56K KIT 

$449 



The new 2K x 8, 24 PIN, static RAMs are the next generation of high density, high 
speed, low power, RAMs. Pioneered by such companies as HITACHI and 
TOSHIBA, and soon to be second sourced by most major U.S. manufacturers, 
these ultra low power parts, feature 2716 compatible pin out. Thus fully 
interchangeable ROM/RAM boards are at last a reality, and you get BLINDING 
speed and LOW power thrown in for virtually nothing. 



Digital Research Computers 

(OF TEXAS) 
P.O. BOX 401565 • GARLAND, TEXAS 75040 • (214)271-3538 



TERMS: Add $2 00 postage We pay balance. Order under $15 add 75C 
handling. No. COD We accept Visa and MasterCharge Tex Res add 5% 
Tax. Foreign orders (except Canada) add 20% P & H . Orders over $50. add 
85C for insurance 



COMPONENTS 



SN7400N 


18 


SN7487N 


30 


SN7402N 


22 


SN7492M 


49 


SM7404N 


21 


SN7493N 


45 


SN7408M 


22 


SN7495M 


SO 


SN7410N 


16 


SN7496M 


69 


SN7412N 


20 


SN74122N 39 


SN7413N 


22 


SN74138M 95 


SN7414N 


29 


SN74141N 69 


SN7416N 


27 


SN741S1N 65 


SN7417M 


29 


SN74153M 36 


SN7420N 


17 


SN741S4M 125 


IM7429M 


20 


SN74155N 75 


SN7430N 


17 


SN74157N 58 


SN7437N 


26 


SN74160N 89 


SN7438N 


24 


SN74161N 65 


SN7440N 


18 


SN74163N 85 


SN7442N 


4S 


SN74164N 87 


SN7443M 


42 


SN74165N 55 


SN744SN 


64 


SN74174N 88 


SN74S1N 


19 


SN7417SN 79 


SN7454N 


19 


SN74160N 75 


SN7474M 


27 


SN74181N 1 15 


SN74 75N 


35 


SN74393N 1 66 


74LS00 




741 SOO 


28 


74LS1S8 


60 


74LS02 


26 


74LS161 


83 


74LS03 


28 


74LS162 


89 


74LS04 


28 


74LS163 


90 


74LS06 


22 


74LS164 


65 


MLS06 


29 


74LS165 


66 


74LS09 


28 


74LS169 


1 56 


74LS10 


26 


74LS170 


1 75 


74LS14 


89 


74 LSI 74 


86 


74LS20 


22 


74LS17S 


85 


74LS21 


26 


74LS190 


85 


74LS2S 


40 


74LS191 


1 25 


74LS27 


27 


74LS196 


96 


74LS28 


37 


74LS197 


78 


74LS30 


29 


74LS221 


1 25 


74LS32 


31 


74LS240 


165 


74LS36 


31 


74 LS241 


165 


74LS42 


63 


74 LS243 


155 


74LS48 


77 


74 LS244 


156 


74LS74 


38 


74 LS245 


245 


74LS7S 


S5 


74 LS251 


1 25 


74LS86 


45 


74LS253 


85 


74LS90 


SO 


74LS257 


85 


74LS93 


65 


74LS259 


195 


74LS96 


SO 


74LS260 


55 


74LS107 


43 


74 LS273 


1 55 


74LS113 


45 


74LS279 


45 


74LS122 


45 


74 LS290 


1 25 


74LS123 


89 


74 LS293 


166 


74LS125 


89 


74LS385 


86 


MLS1M 


79 


74LS367 


75 


74 LSI 38 


64 


74LS370 


1 45 


74 LSI 39 


59 


74 I S3 74 


1 45 


74LS151 


49 


74LS377 


1 25 


74 LSI S3 


49 


74LS669 


1 55 


74LS157 


60 


74LS670 


186 


74S00 




74SOO 


39 


74S138 


75 


74SQ2 


45 


74 SI 40 1 OO 


74 SO 3 


38 


74S158 


75 


74S04 


39 


74S174 1 35 


74S05 


39 


74S1 75 1 


35 


74S10 


39 


74S182 


75 


74S15 


45 


74S189 4 


25 


74S20 


55 


74S201 6 75 


74S22 


55 


74S240 2 75 


74S30 


75 


74S244 2 96 


74S37 


55 


74S251 2 75 


74SSO 


65 


74S287 2 96 


74S51 


49 


74S288 2 96 


74S64 


55 


74S299 5 75 


74S74 


65 


74S470 9 25 


74S86 


95 


74S471 9 SO 


74S112 


1 95 


74S473 9 50 


74S132 


1 45 


74S474 9 SO 




E PROMS 




2706 


3 25m 8 tor 2 96aa 


2716 


Ml 


•a 8 for 5.0Oa» 


2732 


12 98 


aa 4 for 11 00 aa 


4116 300NS 


2 00m 8 tor MOO 


200NS 


2 3b— 6 for 16 00 


21V4L 300NS 


2.25m 4 tor 1 90m 


MM 


245m 4 for 2 OOaa 


| 2111 4SONS 


2 SOaatOtor 2.00m 


atlSC 
2102 


cm Id 




4 SONS 


96 






■on 


296 


MM 


.75 


NES6S 


Zt 


UPD765 


1985 


AV5 1013A 


425 


floppy da* 


w apa 


1486 


96 


control tar 




1489 


95 


ULN2O01 


1.96 


BT26 


130 


TMS4400 


140 


8T28 


130 


MC40O8P 


1.50 


8212 


1.96 


MH0O26 


1.56 


8216 


1.95 


03624 


1.96 


IS410SCR 


85 


D3001 


1.96 


IT410TW1AC 


.86 


D3002 


1 96 


T906 


m 






7908 


85 


i.e. 




7915 


85 




7918 
7805 


85 

as 


SOCKETS 


m 


85 


arw p 


•t 


7808 


85 


8 


10/1.20 


7812 


.86 


O/S30 14 


K)/1 30 


MC1330A1P 


1.60 


10/5 70 16 


KV140 


MC13SOP 


1.15 


tO/8 70 16 


to/rso 


MC1358P 


1 SO 


KV970 20 


1O/270 


LM380 


1.10 


KV12.70 22 


KV2 70 


LMS66N 


•J 5 1O/13.70 24 


tO/270 


LM741 


g 10/V470 28 


KV3 00 


MC14S8P 


■ 10717.70 40 


tO/3 90 


LM720 
LM386 


1 ■■ wirawrap 
CPU* 


aotdar 


Z 80 




7.98 




Z SOACTC 


10 50 




Z 80ACPU 


10 50 




Z 80002 16 


-64K 129.00 




MM 




13.50 




2901 A 




7.50 




MC66O0 


9. SO 





SPECIALS 

ZENITH ZVM-121 

Video Monitor /Green!! 



1 Z inch w4 

15 MHz Af* 

$134.00 

8255^*5.95 
8748-8 — *31XX)| 
3341PC— $ 2.00 

MM5060 — 35c 
MC6800— $ Z75 
MC6802 - $ 1495| 
MC6850 — $ 4.50 
MC 6821 —» *4.9 5 

CARDS 

MICROSOFT 

Z80* 

*295°° 

16K RAM 

*160OO 

VIDEX 

VIDEOTERM 

80 column 

$29500 

KEYBOARD 
ENHANCER 

$12000 

CALIF COMP SYS 

APPLE 
CLOCK 
$12400 

PROTO 
BOARD 

$25°o 
PRINTERS 

EPSON 

MX- 80 
ST:*y£ 

$ 53500| 

FT:^ 

_ $ 645po| 

INTERFACE 
ICARD/CABLE 

$ 7aso 



SUPER SPECIALS 

MRF 901:— RF TRANS. , — , 

I— ► $ 2.75ea [n/J 

AY3-8603-1:— T.V.,GAME CHIP 

! — ► *4.95ea 



4lnch FAN 
"Whisper" 
w/cord 

*8.95 



* * SPECIALS* 4p 

3 inch. COMPUTER FANS w/cord — *9 .95 

2111-256*4 Static RAM — * 1/5 

8155— RAM. I/O, Timer — — ^ 1 1 50 

ER2051— EAROM — $495 

8085A— CPU — $8.50 

MC6800— CPU — $7/5 

UPD 765A— Floppy Disk Controller- $ 1995 

2732A— 250ns EPROM— $1550 

AY5 1013A— 30K Band UART— $2.95 LM 

93419— 64*9 Static RAM— $550 45 ° 

2901A — 4 Bit Slice ^$/.50 

REAL-TIME CLOCK 
CALENDAR ( MSM 5832) 

Description Mono Metal Gate CMOS I C 

Features 

Time. Month. Date. Year. & 

'Day of Week 

* Bus Oriented 
-4 Bit Data Bus 
'4 Bit Address 
•R/WHoldSelec ♦ 

'Inter Signal 

•32 768Khz xtal Control 

• 5v Pow Sup 
'Low Power Dissipation 




'7.45 

W/ SPEC J 

XTAL 
*2.85 



Pnnlei('82?") '3/9 
Disk Drive '565 00 
Modem *169 00 
litsncks * W 00 

Asseitioiei Editor '49 00 
Music Composer l 49 00 

Mailing List 

IV Switch Boi 

16K RAM 
8K RAM 




POWER 
SUPPLY 

MODEL 
#CP198 

input •110/125v 
output — 5vdc 

At 6amps 



Qty price avail 




10 Srniit ii iiiiitiinci 

THEMPD117 

turns an ordinary 
outlet into a cont- 
rolled power source 



♦79150 



^ DISKETTE SALE!! 

WABASH 

5^4 8inch 

SS/SD $ 25.00 *25.00 
SS/DD 27.40 30.40 
DS/SD 34.90 
DS/DD 32.40 37.40 



S 



COMPUTERS 

ATARI" 800™ 
COMPUTER SYSTEM 

400 Computer 8K — * 350 00 
800 Computer 16K — $ 75900 

*800 COMPUTER 

/ W/48K4 *898 00 
Best Buy^ 

ATARI PERIPHERALS: 

Pnnier('82$) '//500 
Recorder '65 00 
lntertace(85o) , W5 00 
Paddles »i/00 

Star Raiders '49 00 
Space Invaders 'WOO 
Chess '32 00 
KmgdM '12 00 
Hangman '12 00 
Blackiaik hi 00 

+ NEW ATA*/* 
* SOFTWARE * 

MISSLE COMMAND- *36.o° 
ASTEROIDS -*36°o 
VIDEO EASEL-*32?o 
3-D TIC-TAC-TOE-*32P° 

APPLE 1 1 Plus" 



'woo 

'8 95 

'15500 
'11900 



Box of 
10 pes 




48k-*\ 199.00 
64*-*1 399.00 



m 



Y. PRICE AVAIL. 



video 

too 



MONITORS 



DYSAN DISKS 

t also available!! 



CONCORD 



v * o* 



"K" 1?.nih ._ 



12. 

12 MM/ 

BLACK & WHITE 
VIDEO MONITOR 

AMD(H ilEEDEXiCorp 



i?mmj AMDtK 

GREEN Phot 
VIDEO MONITOR 




*365°° 



T 



TERMINALS 



• 



1971 SO. STATE COLLEGE 
ANAHEIM, CALIF. 92806 V\! 

( 714 ) 937-0637 «*& *£ 



— NO COD 

*10.MIN ORDER/ CA RES ADD 6% 
FRT. 

,0 >"& ?8 ISM tft 

«jo-3*o aoo ioor> up call 



( 


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a^ ^/ rv< MM)ioo» 


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■■BBBBJ 




IQ12 



Synertek 
«K TM-3 » 

LOW COST 
TERMINAL WITH 
KEYBOARD AND 
VIDEO IOO * 



*689.00 



4 $499.00 



See List of Advertisers on page 210 



Microcomputing, December 1981 197 



WAMECO 

THE COMPLETE PC BOARD HOUSE 
EVERYTHING FOR THE S-100 BUSS 



•* CPU-2 Z80 PROCESSOR BOARD ON BOARD ROM 
AND HARDWARE POWER ON JUMP. 
PCBD $35.95 KIT $135.95 

•* MEM-3 24 ADDRESS LINES EXPANDABLE IN 1K 
INCR. ADDRESSABLE IN 8K BLOCKS. BIDIREC- 
TIONAL BUSSING. 

PCBD $ 42.95 KIT LESS RAM . . . $119.95 

KIT WITH 2114L-4 $475.95 KIT WITH 2114L-2 $549 95 
A&T WITH 2114L-4 $505.95 A&T WITH 2114L-2 $579.95 

•* FPB-1A FRONT PANEL BOARD FOR 8080A AND Z80 
SYSTEMS IMSAI COMPATIBLE. 
PCBD $56.95 KIT $1 75.00 

*• EPM-2 16/32K ROM USES 2716 OR 2708. ADDRESS- 
ABLE IN 4K BOUNDARIES. 
PCBD .... $33.95 KIT (LESS ROMS) .... $74.95 

■* CPU-1 8080A PROCESSOR BOARD WITH VECTOR 
INTERRUPT. 
PCBD $33.95 KIT $124.95 



#• QMB-12 13 SLOT MOTHER BOARD 
PCBD $42.95 KIT . 



■* QMB-9 9 SLOT MOTHER BOARD. 
PCBD $35.95 KIT 



$125.95 



$109.95 



■fr PTB-1 POWER SUPPLY AND TERMINATOR BOARD. 
PCBD $29.95 KIT $49.95 

#• RTC-1 REAL TIME CLOCK BOARD WITH TWO 
INTERRUPTS. 
PCBD $29.95 KIT $79.95 



#• MEM-1A 8K RAM, USES 2102's. 

PCBD $33.95 KIT (LESS RAM) 



$71.95 



■* IOB-1 I/O BOARD. ONE SERIAL, TWO PARALLEL 
WITH CASSETTE. PCBD $33.95 

•* FDC-1 A FLOPPY DISC CONTROLLER BOARD USES 
1771. PCBD $45.95 



FUTURE PRODUCTS: 80 CHARACTER VIDEO BOARD. 

8 PARALLEL PORT I/O BOARD. 

DEALER INQUIRIES INVITED, UNIVERSITY DISCOUNTS AVAILABLE 

AT YOUR LOCAL DEALER 



W7T7C 



/ne. 



WAMECO, INC., P.O. BOX 877 • EL GRANADA, CA 94018 • (415) 728-9114 



■J CALIFORNIA COMPUTER SYSTEMS 

SI 00 

2132 32K STATIC RAM A&T 

450 NSEC $579 00. 300 NSEC $585 00, 200 NSEC $629.00 

21 If 16K STATIC RAM A&T 

450 NSEC $285 00. 300 NSEC $289 00, 200 NSEC $329.00 

2065 64K DYNAMIC RAM A&T $548 95 

2200 S-100 MAIN FRAM A&T $379.95 

2422 FLOPPY DISC WITH CP/M 2 2" $329 95 

2002 6502 PROCESSOR A&T $282 95 

2I10A Z80 CPU A & T. . $249 95 

2710A 4 SERIAL 1/0 A & T $291.95 

2710A 2 SERIAL. 2 PARALLEL A&T $305.95 

2720A 4 PARALLEL A&T $214 95 

PR0T0 BOARDS WW $39 95. S0LDERTAIL $29 95 

APPLE PRODUCTS 

7114A 12K R0M/PR0M $68 50 

7424A CALENDAR/CLOCK $106 95 

7440A PROGRAMMABLE TIMER $98.50 

7470A A TO CONVERTER $105.95 

74I0A GPIB (IE 488) INTERFACE $26595 

7710A ASYNC SERIAL $12595 

7712A SYNC SERIAL $15395 

7710A PARALLEL STANDARD $98 95 

77201 PARALLEL CENTRONICS $98 95 

70111 ARITHMETIC PROCESSOR W/DISC $342 95 

7811 C ARITHMETIC PROCESSOR W/ROM $342 95 

7500A WW BOARD $22 95 

7510A SOLDERTArt BOARD $23 95 

S0FTVME 

2010 CP/M-MACR0 ASSEMBLER ON DISK $76 95 

2620 CP/M'" SYMBOLIC INSTRUCTION DEBUGGER $64.25 

2030 CP/M'"TEXT FORMATER $64 25 

2040 CP/M'" BACKGROUND PRINT UTILITY $42 95 



OTHER CCS PRODUCTS ARE AVAILABLE. 
CALL FOR PRICE 



SStV 



MICROCOMPUTER PRODUCTS 



SI 00 PRODUCTS 
C6IA 8080 PROCESSOR PCBD $32 95 

KIT $15595, A&T $215 95 

C8-2 280 PROCESSOR BOARD. 

KIT $198 95, A&T $269 95 

V6IC 64 x 16 VIDEO, PCBD $32 95 

KIT $15395, A&T $19995 

VB2 64 x 16 VIDEO, PCBD $32 95 

KIT $175.95, A&T $234 95 

VB3 80 CHARACTER VIDEO 4MHZ 

KIT $345 95, A&T $425 95 

UPGRADE RAMS FOR VB-3 $42 00 

104 2 PARALLEL, 2 SERIAL, PCBD $32 95 

KIT $15595, A&T $194 95 

PB-1 2708, 2716 PROGRAMMER BOARD 

KIT $135.95, A&T $185 95 

MB-10 16K STATIC RAM 

KIT $299.95, A&T $339 95 

APPLE PRODUCTS 
A488 IEEE 488 INTERFACE $399.95 

AI0 SERIAL/PARALLEL INTERFACE 

KIT $125 95, A&T $15595 

ASI0 SERIAL I/O 

KIT $87 95, A&T $97 95 

API0 PARALLEL 10 

KIT (W/0 CABLES) $67 95, A&T(W/0 CABLES) $87 95 

OTHER SSM PRODUCTS ARE AVAILABLE. 
CALL FOR PRICES. 



M 




MONDAY-FRIDAY. 8 OO TO 1 2 OO. 1 OO TO 5 30 
THURSDAYS, 8:00 TO 9:00 P M 

(415)728-9121 
P.O. BOX 955 • EL GRANADA, CA 94018 

PLEASE SEND FOR IC, XIST0R AND COMPUTER PARTS LIS! 



DEC. SPECIAL SALE 
ON PREPAID ORDERS 

(CHARGE CARDS AND COD OR P0 I0T AVAILABLE ON THESE OFFERS) 

XMAS SALE 

5% OFF OF CCS AND SSM PCBD AND KITS. 

7'/2% OFF OF WAMECO PCBD S AND KITS. 

"***** inc. WAMECO INC. 
BOARDS WITH MIKOS PARTS 

MEM-3 32K STATIC RAM. PCBD $36 95 

KIT LESS RAM $95 95 A & T $135 95 

CPU-2 Z80 PROCESSOR. PCBD $32 95 

KIT LESS ROM S10995. A&T $14995 

EPM-2 16K/32K EPROM. PCBD $32 95 

KIT LESS ROM 565 95. A&T $99 95 

FPB-I FRONT PANEL. PCBD $48 50 

KIT $144 95. A& T $184 95 

CPU-1 8080 PROCESSOR, PCBD $29 95 

KIT $89 95, A&T $129 95 

QMB-12 13 SLOT MOTHER BOARD. PCBD $39 95 

KIT $95 95, A&T S135 95 

OTHER WAMECO PRODUCTS ARE AVAILABLE 
CALL FOR PRICES 

MIKOS PARTS ASSORTMENTS ARE ALL FACTORY MARKED PARTS KITS INCLUDE 
ALL PARTS LISTED AS REQUIRED FOR THE COMPLETE KIT LESS PARTS LISTED 
ALL SOCKETS INCLUDEO 

LARGE SELECTION OF LS TTL AVAILABLE. 

PURCHASE $50 00 WORTH OF LS TTL AND GET 1 0% CREDIT 
TOWARD ADDITIONAL PURCHASES PREPAID ORDERS ONLY 



VISA or MASTERCHARGE Send account number interbank number expiration date 
and sign your order Approx postage will be added Check or money order will be sent 
post paid m u S II you are not a regular customer please use charge cashier s check or 
postal money order Otherwise there will be a two-week delay tor checks to clear Caiil 
residents add 6 * tax Money back 30-day guarantee We cannot accept returned IC s 
that have been soldered to Prices subiect to change without notice SIO i 
$1 SO untei chii|i u irton i«u tin SHOO 



1 98 Microcomputing, December 1981 



• 



• 





• 



Single User System 

SBC-200, 64K ExpandoRAM U, Versa/ loppy II, CP/M 2.2 

$995.00 

4 MHz Z-80A CPU, 64K RAM, serial I/O port, 
parallel I/O port, double-density disk controller, 
CP/M 2.2 disk and manuals, system monitor, 
control and diagnostic software. 

-All boards are assembled and tested- 

ExpandoRAM III 

64K to 256K expandable RAM board 




SD Systems has duplicated the famous 
reliability of their ExpandoRAM I and II boards 
in the new ExpandoRAM III, a board capable of 
containing 256K of high speed RAM. Utilizing the 
new 64K x 1 dymanic RAM chips, you can 
configure a memory of 64K, 128K, 192K, or 256K, 
all on one S-100 board. Memory address decoding 
is done by a programmed bipolar ROM so that the 
memory map may be dip-switch configured to 
work with either COSMOS/MPM-type systems or 
with OASIS-type systems. 

Extensive application notes concerning how to 
operate the ExpandoRAM III with Cromemco, 
Intersystems, and other popular 4 MHz Z-80 
systems are contained in the manual. 

MEM-65064A 64K A&T $495.00 

MEM-65128A 128K A & T $639.95 

MEM-65192A I92K A&T $769.95 

MEM-65256A 256K A&T $879.95 

Versafloppy II 

Double density controller with CP/M 2.2 




• S-100 bus compatible • IBM 3740 compatible 
soft sectored format • Controls single and double- 
sided drives, single or double density, 5Va" and 8" 
drives in any combination of four simultaneously 
• Drive select and side select circuitry • Analog 
phase-locked loop data seperator • Vectored 
interrupt operation optional • CP/M 2.2 disk and 
manual set included • Control /diagnostic 
software PROM included 

"he Versafloppy II is faster, more stable and more 
tolerant of bit shift and "jitter" than most 
controllers. CP/M 2.2 and all necessary control 
and diagnostic software are included. 

IOD-1160A A & T with CP/M 2.2 . . $370.00 



SBC-200 

2 or 4 MHz single board computer 




• S-100 bus compatible • Powerful 4MHz Z-80A 
CPU • Synchronous/asynchronous serial I/O 
port with RS-232 interface and software 
programmable baud rates up to 9600 baud • 
Parallel input and parallel output port • Four 
channel counter/timer • Four maskable, vectored 
interrupt inputs and a non-maskable interrupt • 
IK of onboard RAM • Up to 32K of onboard 
ROM • System monitor PROM included 

The SBC-200 is an excellent CPU board to base a 
microcomputer system around. With on-board 
RAM, ROM, and I/O, the SBC-200 allows you to 
build a powerful three-board system that has the 
same features found in most five-board 
microcomputers. The SBC-200 is compatible with 
both single-user and multi-user systems. 

CPU-30200A A&T with monitor . $299.95 

ExpandoRAM II 

16K to 64K expandable RAM board 




• S-100 bus compatible • Up to 4MHz operation • 
Expandable from 16K to 64K • Uses 16 x 1 4116 
memory chips • Page mode operation allows up to 
8 memory boards on the bus • Phantom output 
disable • Invisible on-board refresh 

The ExpandoRAM II is compatible with most S- 
100 CPUs. When other SD System' series II 
boards are combined with the ExpandoRAM II, 
they create a microcomputer system with 
exceptional capabilities and features. 

MEM-16630A 16K A & T $325.00 

MEM-32631A 32K A&T $345.00 

MEM-48632A 48K A&T $365.00 

MEM-64633A 64K A&T $385.00 

COSMOS 

Multi-user operating system 

• Multi-user disk operating system • Allows up to 
8 users to run independent jobs concurrently • 
Each user has a seperate file directory 

COMOS supports all the file structures of CP/M 
2.2, and is compatible at the applications program 
level with CP/M 2.2, so that most programs 
written to run under CP/M 2.2 or SDOS will also 
run under COSMOS. 

SFC-55009039F COSMOS on 8" disk $395.00 



Multi-User System 

SBC-200, 256K ExpandoRAM III, Versafloppy II, MPC4 
COSMOS Multiuser Operating System, C BASIC II 

$1 995. 00 

Two Z-80A CPUs (4 MHz), 256K RAM, 5 serial I/O 
ports with independently programmable baud 
rates and vectored interrupts, parallel input port, 
parallel output port, 8 counter/timer channels, 
real time clock, single and double sided/single or 
double density disk controller for 5'/i" and 8" 
drives, up to 36K of onboard ROM, CP/M 2.2 
compatible COSMOS interrupt driven multi-user 
disk operating system, allows up to 8 users to run 
independent jobs concurrently, C BASIC II, 
control and diagnostic software in PROM 
included. 

-All boards are assembled and tested- 

MPC-4 

Intelligent communications interface 



I 






~irJW 






• Four buffered serial I/O ports • On-board Z- 
80A processor • Four CTC channels • 
Independently programmable baud rates • 
Vectored interrupt capability • Up to 4K of on- 
board PROM • Up to 2K of onboard RAM • On- 
board firmware 

This is not just another four-port serial 
I/O board! The on-board processor and firmware 
provide sufficient intelligence to allow the MPC-4 
to handle time consuming I/O tasks, rather than 
loading down your CPU. To increase overall 
efficiency, each serial channel has an 80 character 
input buffer and a 128 character output buffer. 
The on-board firmware can be modified to make 
the board SDLC or BISYNC compatible. In 
combination with SD's COSMOS operating 
system (which is included with the MPC-4), this 
board makes a perfect building block for a multi- 
user system. 



IOI-1504A A & Twith COSMOS 



$495.00 




I 



Place Orders Toll Free 

■ Continental U.S. Inside California 

800-421-5500 800-262-1710 




For Technical Inquires or Customer Senice call: 

213-973-7707 



■ 




*^48 



Computer Products 



■ 
■ 




1901 W. Rosccrans, Hawthorne, Ca 90250 

TKRMS of SALE: Cash, checks, credit cards, or 
Purchase Orders from qualified firms and institutions. 
.Minimum Order $15.00. California residents add 6% 
tax. Minimum shipping & handling charge $.'}.()(). 
Pricing & availibility subject to change 






^48 



Computer Products 



Printers 



Accessories for Apple Single Board Computer 



BETTER THAN EPSON ! - Okidata 

Microline 82A ho 132 column. 120 CPS, 9x9 dot 

matrix, friction feed, pin feed, adjustable tractor feed 
(removable), handles 4 part forms up to 9.5" aide, rear & 
bottom feed, paper tear bar, 100% duty cycle 200 .000 \ 000 
character print head, bidirectional logic seeking, both 
serial & parallel interfaces included, front panel switch & 
program control of 10 different form lengths, uses 
inexpensive spool type ribbons, double width & condensed 
characters, true loner COSe descenders & graphics 

PRM-43082 with FREE tractor .... $539.95 
Microline 83A 132 232 column. 120 CPS. handles 

forms up to 15" wide, plus all the features of the H2A. 

PRM-43083 with FREE tractor .... $749.95 

PRA-27081A Apple card $39.95 

PRA-27082A Apple cable $19.95 

PRA-27087A TRS-80 cable $24.95 

PRA-43080 Extra ribbons pkg. of 2 ... $9.95 

INEXPENSIVE PRINTERS - Epson 

MX-70 SO column. HO ('PS, 5x7 dot matrix, adjustable 
tractor feed, & graphics 

PRM-27070 List $459 $399.95 

MX-80 HO column, HO CPS, bidirectional logic seeking 
printing, 9x9 dot matrix, adjustable tractor feed, & 64 
graphics characters 

PRM-27080 List $645 $469.95 

MX-80FT same as MX HO with friction feed added. 

PRM-27082 List $745 $559.95 

MX-100 132 column, correspondence quality, graphics, 
up to 15" paper, friction feed & adjustable tractor feed, 9x9 
dot matrix, HO CPS. 

PRM-27100 List $945 $759.95 

PRA-27084 Serial interface $69.95 

PRA-27088 Serial intf & 2K buffer . . $144.95 

PRA-27081 Apple card $74.95 

PRA-27082 Apple cable $22.95 

PRA-27086 IEEE 488 card $52.95 

PRA-27087 TRS-80 cable $32.95 

PRA-27085 Graftrax II $95.00 

PRA-27083 Extra ribbon $14.95 

NEC 7700 & 3500 

NEC Spinwriter w/Intelligent Controller 

Standard serial, Centronics parallel, and current 
loop interfaces • Selectable baud rates 50 to 19,200 

• Automatic bidirectional printing • Logic 
seeking • 650 character buffer with optional 16K 
buffer • f). r ) characters per second print speed • 
Comes with vertical forms tractor, ribbon, thimble 
and cable • Diablo compatible software • 
Available with or without optional front panel 

PRD-55511 IK no front panel .... $2795.00 

PRD-55512 16K no front panel .. $2895.00 

PRD-55515 IK w/ front panel $2995.00 

PRD-55516 16K w front panel $3095.00 

Intersell NEC 3500Q 

New from NEC - the 3500 series Spin writers. 
Incorporates all the features and reliability of the 
5500 and 7700 series Spinwriters into an 
inexpensive 30 CPS letter quality printer with an 
optional bi-directional tractor assembly. 

PRD-55351 3S00Q IK $1995.00 

PRD-55352 :i500Q 16K $2095.00 

PRA-55100 Deluxe tractor option .. $300.00 



16K MEMORY UPGRADE 

Add 16K of RAM to your TRSHO, Apple, or Exidy in just 
minutes. We're sold thousands of these 16K RAM 
upgrades which include the appropriate memory chips (as 
specified by the manufacturer), all necessary jumper 
blocks, fool-proof instructions, and our 1 year guarantee. 

MEX-16100K TRS-80 kit $25.00 

MEX-16101K Apple kit $25.00 

MEX-16102K Exidy kit $25.00 

16K RAM CARD - for Apple II 

Expand your Apple to 64 K, 1 year warranty 
MEX-16500A Save $70.00 ffl $129.95 



Z-80* CARD for APPLE 

Two computers in one, Z-H0 & 6502, more than doubles the 
power & potential of your Apple, includes Z-80* CPU card, 
CP M 2.2. & BASIC HO 

CPX-30800A A & T $299.95 



8" DISK CONTROLLER 

New from Vista Computer, single or double sided, single or 
double density, compatible with DOS 3.2/3.3, Pascal, & CPM 
2.2. Shugart & Qume compatible 

IOD-2700A A & T $499.95 

2 MEGABYTES for Apple II 

Complete package includes: Two 8" double-density disk 
dm <\s, Vista double-density 8" disk controller, cabinet, power 
supply, & cables, DOS 3.2/3.3, CP/M 2.2, & Pascal 
compatible. 

1 MegaByte Package (Kit) $1495.00 

1 MegaByte Package (A & T) $1695.00 

2 MegaByte Package (Kit) $1795.00 

2 MegaByte Package (A & T) $19.95 

CPS MULTICARD - Mtn. Computer 

Three cards in one! Real time clock calendar, serial interface. 
<V parallel interface all on one card. 

IOX-2300A A & T $199.95 

AIO, ASIO, APIO - S.S.M. 

Parallel & serial interface for your Apple (see Byte pg 11) 

IOI-2050K Par & Ser kit $139.95 

IOI-2050A Par&SerA&T $169.95 

IOI-2052K Serial kit $89.95 

IOI-2052A Serial A&T $99.95 

IOI-2054K Parallel kit $69.95 

IOI-2054A Parallel A&T $89.95 

A488 - S.S.M. 

IEEE 488 controller, uses simple basic commands, 
includes firmware and cable, 1 year guarantee, (see April 
Bxte pg 11) 

IOX-7488A A&T $399.95 



■■ 



Modems 



CAT MODEMS - Novation 

CAT 300 baud, acoustic, answer orginate 

IOM-5200A List $189.95 $149.95 

D-CAT 300 baud direct connect, answer orginate 

IOM-5201A List $199.95 $169.95 

AUTO-CAT Auto answer orginate, direct connect 

IOM-5230A List $299.95 $239.95 

Apple-CAT - Novation 

Software selectable 1200 or 300 baud, direct connect, auto- 
ansuer autodial, auxiliary 3 wire RS232C serial port for 

printer. 

I OM -5232 A Save $50.00!!! $325.00 

SMARTMODEM - Hayes 

Sophisticated direct connect auto-answer auto-dial modem, 
touch-tone or pulse dialing. RS-232C interface, programmable 

IOM-5400A Smartmodem $269.95 



;! 



AIM-65 - Rockwell 

6502 computer wit/i alphanumeric display, printer. & 
keyboard, and complete instructional manuals 

( PK-50165 IK AIM $424.95] 

CPK-50465 IK AIM $474.95 

SFK-71600008E HK BASIC ROM .. $64.95 
SFK-64600004E IK assembler ROM $43.95 

PSX-030A Power supply $64.95 

ENX-000002 Enclosure $54.95| 

IK AIM. HK BASIC, power nupply, <£■ enclosure 
Special package price $649.95 

Z-80 STARTER KIT - SD Systems 

Complete Z-80 microcomputer with RAM, ROM, I/O, 
keyboard, display, kludge area, manual, & workbook 

CPS-30100K KIT $299.95 

CPS-30100A A&T $469.95 

SYM-1 - Synertek Systems 

Single board computer with I K of RAM. IK of ROM, key pad. 
LEI) display. 20ma & cassette interface on board. 

CPK-50020A A A T $249,951 



Video Monitors 



HI-RES 12" GREEN - Zenith 

IS MHz bandwidth. 700 lines inch. P31 green phosphor, 
switchublc 40 or 80 columns, small, light weight & portable. 
VDM-201201 List price $150.00 .... $1 18.95 

Leedex / Amdek 

Reasonably priced video monitors 

VDM-801210 Video 100 12" B&W . . $139.95 
VDM-801230 Video 100-80 12" B& W $179.95 
VDM-801250 12" Green Phospor .... $169.95 
VDC-801310 13" Color I $379.95 

12" COLOR MONITOR - NEC 

Hires monitor with audio & sculptured case 

VDC-651212 Color Monitor $479.95 

12" GREEN SCREEN - NEC 

20 MHz. P31 phosphor video monitor with audio, 
exceptionally high resolution - A fantastic monitor at a 
eery reasonable price 

VDM-651200 Special Sale Price $199.95 



Video Terminals 



AMBER SCREEN - Volker Craig 

Detachable keyboard, amber on black display. 7 x 9 dot 
matrix. 10 program function keys. II key numeric pad. 12" 
non glare screen. SO to 19.200 baud, direct cursor control, 
auxiliary bidirectional serial port 

VDT-351200 List $795.00 $645.00 

VIEWPIONT - ADDS 

Dctai liable keyboard, serial RS232C interface, baud rates 
from 1 10 to 19.200. auxiliary serial output fxirt. 2 1 x SO display . 

VDT-501210 Sale Priced $639.95 1 

TELEVIDEO 950 
VDT-901250 List $1195.00 $995.00 

DIALOGUE 80 - Ampex 
VDT-230080 List $1 195.00 $895,001 




»^48 



Computer Products 



S-100 CPU Boards 



THE BIG Z* - Jade 

2 or 4 MHz switchable Z-80* CPU with serial I/O, 
accomodates 2708, 2716, or 2732 EPROM. baud rates from 
75 to 9600 

CPU-30201K Kit $139.95 

CPU-30201A A&T $189.95 

CPU-30200B Bare board $35.00 

2810 Z-80* CPU - Cal Comp Sys 

2 4 MHz ZHOA* CPU with KS-232C serial 1 O port and on- 
board MOSS 2.2 monitor PROM, front panel compatible. 
CPU-30400A A & T $269.95 

CB-2 Z-80 CPU - S.S.M. 

2 or 4 MHz Z-80 CPU board with provision for up to 8K of 
ROM or 4K of RAM on hoard, extended addressing, IEEE 
SI 00, front panel compatible. 

CPU-30300K Kit $239.95 

CPU-30300A A & T $299.95 



S-100 PROM Boards 



PROM- 100 - SD Systems 

2708, 2716, 2732 EPROM programmer w/software 

MEM-99520K Kit $189.95 

MEM-99520A A & T $249.95 

PB-1 - S.S.M. 

2708, 2716 EPROM board with built-in programmer 

MEM-99510K Kit $154.95 

MEM-99510A A&T $219.95 

EPROM BOARD - Jade 

16K or 32K uses 2708's or 2716's, IK boundary 

MEM-16230K Kit $79.95 

MEM-16230A A&T $119.95 



S-100 Video Boards 



VB-3 - S.S.M. 

80 characters x 24 lines expandable to 80 x 48 for a full page 
of text, upper & lower case, 256 user defined symbols, 160 x 
192 graphics matrix, memory mapped, has key board 
input. 

IOV-1095K 4 MHz kit $349.95 

IOV-1095A 4 MHz A&T $439.95 

IOV-1096K 80 x 48 upgrade $39.95 

VDB-8024 - SD Systems 

80 x 24 I O mapped video board with keyboard I O, and 
on board Z-80 A*. 

IOV-1020A A&T $459.95 

VIDEO BOARD - S.S.M. 

64 characters x 16 lines. 128 x 48 matrix for graphics, full 
upper loner case ASCII character set, numbers, symbols, 
and greek letters, normal reverse blinking video, S-100. 

IOV-1051K Kit $149.95 

IOV-1051A A&T $219.95 

IOV-1051B Bare board $34.95 



S-100 Motherboards 



ISO-BUS - Jade 

Silent, simple, and on sale a better motherboard 
6 Slot (5 'A" x 8%") 

MBS-061B Bare board $19.95 

MBS-061K Kit $39.95 

MBS-061 A A&T $49.95 

12 Slot (9Vi" x 8H") 

MBS-121B Bare board $29.95 

MBS-121K Kit $69.95 

MBS-121A A&T $89.95 

18 Slot (14¥»" x 8%") 

MBS-181B Bare board $49.95 

MBS-181K Kit $99.95 

MBS-181A A&T $139.95 



S-100 RAM Boards 



MEMORY BANK - Jade 

4 MHz. S-100, bank selectable, expandable from 16Kto64K 

MEM-99730B Bare Board $49.95 

MEM-99730K Kit no RAM $199.95 

MEM-32731K 32 K Kit $239.95 

MEM-64733K 64K Kit $279.95 

Assembled & Tested add $50.00 

64K RAM - Calif Computer Sys 

4 MHz bank port bank byte selectable, extended 
addressing. 16K bank selectable, PHANTOM line allows 
memory overlay, 8080 / Z-80 / front panel compatible. 
MEM-64565A A&T $575.00 

64K STATIC RAM - Mem Merchant 

64K static S-100 RAM card, 4 16K banks, up to 8MHz 
MEM-64400A A&T $789.95 

32K STATIC RAM - Jade 

2 or 4 MHz expandable static RAM board uses 2114L's 

MEM-16151K 16K4MHzkit $169.95 

MEM-32151K 32K 4 MHz kit $299.95 

Assembled & tested add $50.00 

16K STATIC RAM - Mem Merchant 

4 MHz 16K static RAM board, IEEE S100, bank selectable. 
Phantom capability, addressable in 4K blocks, "disable-able" 
in IK segments, extended addressing, low power 
MEM-16171A A&T $164.95 



S-100 Disk Controllers 



DOUBLE-D - Jade 

Double density controller with the inside track, on-board Z- 
80A*, printer port, IEEE S-100, can function on an 
interrupt driven buss 

IOD-1200K Kit $299.95 

IOD-1200A A&T $375.00 

IOD-1200B Bare board $59.95 

DOUBLE DENSITY - Cal Comp Sys 

.)' /" and 8" disk controller, single or double density, with 
onboard boot loader ROM. and free CPM 2.2* and 
manual set. 

IOD-1300A A&T $374.95 



S-100 I/O Boards 



S.P.I.C. - Jade 

Our new I/O card with 2 SIO's, 4 CTC's, and 1 PIO 
IOI-1045K 2 CTC's, 1 SIO, 1 PIO . . $179.95 

IOI-1045A A&T $239.95 

IOI-1046K 4 CTC's, 2 SIO's, 1 PIO $219.95 

IOI-1046A A&T $299.95 

IOI-1045B Bare board w/ manual . . . $49.95 

1/0-4 - S.S.M. 

2 serial 1 O ports plus 2 parallel I/O ports 

IOI-1010K Kit $179.95 

IOI-1010A A&T $249.95 

IOI-1010B Bare board $35.00 



S-100 Mainframes 



MAINFRAME - Cal Comp Sys 

12 slot S-100 mainframe with 20 amp power supply 

ENC-112105 Kit $329.95 

ENC-1 12106 A & T $399.95 

DISK MAINFRAME - N.P.C. 

Holds 2 8" drives and a 12 slot S 100 system. Attractive 
metal cabinet with 12 slot mot herboard & card cage, power 
supply, dual fans, lighti-d switch, a