PART 5
DOS/BATCH DEVICE DRIVERS
PART 5
CHAPTER 1
USING DEVICE DRIVERS OUTSIDE DOS/BATCH
S\abroutines to handle I/O transfers between a PDP-11 and each of Its peripheral
devices are developed as required for use within the Disk Operating System DOS /BATCH.
These subroutines are made available within an I/O Utilities Package for the benefit
of PDP-11 users who have configurations unable to support DOS/BATCH or who wish to
run programs outside DOS/BATCH control.
All the subroutines associated with one peripheral device form an entity known as a
device driver. This part provides a general description of a driver and shows how
it can be used in a stand-alone environment. The unique properties of each driver
are discussed in separate docviments, which are made available as part of the Device
Driver Package. The I/O utilities package for any system is determined by the
peripherals of that system. Thus, the full documentation for a particular package
consists of this document and applicable supplements.
5-1
PART 5
CHAPTER 2
DRIVER FORMAT
2.1 STRUCTURE
The basic principle of all drivers under the DOS/BATCH Monitor is that they must
present a common interface to the routines using them in order to provide device-
independent operation. The subroutines are structured to meet this end. Moreover,
a driver can be loaded anywhere in memory under Monitor Control. Its code is always
position-independent (PIC) .
A detailed description of a driver is found in Chapter 5-4. This section describes
driver interfaces.
2.1.1 Driver Interface Table
The first section of each driver is a table which contains, in a standard format,
information on the nature and capabilities of the device it represents and entry
points to each of its subroutines. The calling program can use this table as
required, regardless of the device being called. See Section 5-4.1 for a detailed
description of the table.
2.1.2 Setup Routines
Each driver is expected to handle its device under the PDP-11 interrupt system.
When called by a program, therefore, a driver subroutine merely initiates the required
action by setting the device hardware registers appropriately. It returns to the
calling program by a standard subroutine exit.
The main setup routines prepares for a data transfer to or from the device, using
parameters supplied by the calling program. Normally, blocks of data are moved at
each transfer. The driver returns control to the program only when the whole
block has been transferred or when it is unable to continue because there is no
more data available.
^See Part 6 for information on PIC.
5-2
The driver can also contain subroutines by which the calling program can request
(1) start-up or shut-dovm action, sych as leader or trailer functions for a paper
tape punch, or (2) some special function provided by the device hardware (or a
software simulation of that for some similar device), e.g., rewind of a magnetic
tape or DECtape.
2.1.3 Interrupt Servicing
The driver routine to service device interrupts is particularly dependent upon the
device hardware provisions for controlling transfers. In general, the driver
determines the cause of the interrupt and checks whether the last action was
performed correctly or was prevented by some error condition. If more device
action is needed to satisfy the program request, the driver again initiates that
action and takes a normal interrupt exit. If the program request has been fully
met, control is returned to the program at an address supplied at the time of the
request.
2.1.4 Error Handling
Device errors can be handled in two ways. There are some errors for which recovery
can be programmed; the driver, if appropriate, attempts this itself (as in the case
of parity or timing failure on a bulk-storage device) or recalls the program with the
error condition flagged (as at the end of a physical paper tape) . Other errors
normally require external action, perhaps by an operator. The driver calls a DOS/
BATCH error handler via an lOT call, with supporting information on the processor
stack.
2.2 INTERFACE TO THE DRIVER
2.2.1 Control Interface
The principal link between a calling program and any driver subroutine is the first
word of the driver table (link word) . In order to provide the control parameters
for a device operation, the calling program prepares a list in a standardized form
and places a pointer to the list in the link word. The called driver uses the
pointer to access the parameters. The driver can place return status information
(if needed) in the list area via the link word. The first word of the driver table
can also act as a busy indicator; if it is 0, the driver is not currently performing
a task, but if it contains a listpointer, the driver can be assumed to be busy.
Since most drivers support only one job at a time, the link word state is significant.
5-3
2.2.2 Interrupt Interface
Although the driver expects to use the interrupt system, it does not itself ensure
that its interrupt vector in the memory area below 400 has been set up correctly;
8
the Monitor takes care of this. However, the driver table contains the information
required to initialize the appropriate vector.
5-4
PART 5
CHAPTER 3
STAND-ALONE USE
Because each driver is designed for operation within the device-independent frame-
work of the Monitor, it can be similarly used in other applications. Since the
easiest way to use the driver is to assemble it with the program that requires
it, this method will be described first. Other possible methods will be discussed
later.
3.1 DRIVER ASSEMBLED WITH PROGRAM
■3.1.1 Setting Interrupt Vector
As noted in Section 5-2.2.2, the calling program must initialize the device
transfer vect9r within memory locations 0-377. The address of the driver's interrupt
entry point can be identified on the source listing by the symbolic name which appears
as the contents of the Driver Table Byte, DRIVER+5. The priority level at which the
driver expects to process the interrupt is at byte DRIVER+6. For a program which
can reference position-dependent code, the setup sequencer might be:
MOV
MOVB
CLRB
#DVRINT, VECTOR ;SET INT. ADDRESS
DRIVER+6 ,VECT0R+2 ;SET PRIORITY
VECTOR+3 ; CLEAR UPPER STATUS BYTE
where the Driver Table Byte (at DRIVER+5) shows the follwing instruction:
.BYTE DVRINT-DRIVER
If the program must be position-independent, it can take advantage of the fact that
the Interrupt Entry address is stored as an offset from the start of the driver, as
illustrated above. In this case, a sample sequence might be:
MOV
ADD
MOV
CLR
MOVB
ADD
CLR
MOVB
PC,R1 .
#DRIVER-.,R1
#VECT0R,R2
(aR2
5(R1),@R2
R1,(R2) +
@R2
6(Rl),(aR2
;GET DRIVER START
... & VECTOR ADDRESSED
SET INT. ADDRESS
. . .AS START ADDRESS+OFFSET
SET PRIORITY
5-5
3.1.2 Parameter Table for Driver Call
For any call to the driver the program must provide a list of control arguments
mentioned in Section 5-2.2.1. This list must adhere to the following format:^
[SPECIAL FUNCTION POINTER]'^
[BLOCK NO.]^
STARTING MEMORY ADDRESS FOR TRANSFER
NO. OF WORDS to be transferred {2's complement)
STATUS CONTROL showing in Bits:
0-2 Function (octally 2=WRITE, 4=READ) **
8-lJZf Unit (if Device can consist of several units, e.g., DECtape)
11 Direction for DECtape -travel (0=Forward)
ADDRESS for RETURN ON COMPLETION
[RESERVED FOR DRIVER USE] ®
The list can be assembled in the required format since its content will not vary.
The driver can return information in this area; this will not corrupt the program
data .
On the other hand, most programs will probably use the same list area for several
tasks or even for different drivers. In this case, the program must contain
the necessary routine to set up the list for each task before making the driver
call. The driver may refer to the list again when it is recalled by an interrupt
or when returning information to the calling program. Therefore, the list must not be
changed until any driver has completed a function requested; for concurrent opera-t
tions, different list areas must be provided.
'^In some cases, it can be further extended as discussed in later sections.
^Required only if Driver is being called for Special Function; addresses a Special
Function Block.
^Required only if the device is bulk storage (e.g.. Disk or DECtape).
**Most devices transfer words regardless of their content, i.e., ASCII or Binary.
Some devices (e.g.. Card Reader) may be handled differently depending on the mode
for these. Bit must also be set to indicate ASCII=0, Binary =1. In these cases,
the driver always produces or accepts ASCII even though the device itself uses some
other code.
'This word may be omitted if the device is bulk storage.
5-6
3.1.3 Calling the Driver
To enable the driver to access the parameter list/ the program must set the first
word of the driver to an address six bytes less than that of the word containing the
MEMORY START ADDRESS. It can then directly call the required driver subroutine
by a normal JSR PC,xxxx call, where xxxx is the address of the driver subroutine.
As an example, the following position-independent code might appear in a program
which wishes to read Blocks #100-103 backward from DECtape unit 3 into a buffer
starting at address BUFFER.
WAIT:
TABLE!
MOV
PC,R0
ADD
#TABLE+12-.,R0
MOV
PC,@R0
ADD
#RETURN-.,@R0
MOV
#5404,- (R0)
MOV
#^1024., ~(R0)
MOV
PC,-(R0)
ADD
#BUFFER-.,@R0
MOV
#l)2i3,-(R0)
CMP
-(R0),-(R0)
MOV
' R0,DT
JSR
PCDT.TFR
•WORD
.WORD
.WORD
.WORD
.WORD
.WORD
;GET TABLE ADDRESS
GET AND STORE...
...RETURN ADDRESS
SET READ REV. UNIT 3
4 BLOCKS REQUIRED
GET AND STORE
. ..BUFFER ADDRESS
START BLOCK
SUBTRACT 4 FROM POINTER
SET DRIVER LINK
GO TO TRANSFER ROUTINE
RETURNS HERE WHEN
. . .TRANSFER UNDER WAY
RETURNS HERE WHEN
. . .TRANSFER COMPLETE
LIST AREA SET
. . .BY ABOVE SEQUENCE
3.1.4 User Registers
During its setup operations for the function requested, the driver assumes that
Processor Registers 0-5 are available for its use. If their contents are of value,
the program must save them before the driver is called.
While servicing intermediate interrupts, the driver may need to save or restore
its registers. It expects to have two subroutines available for the purpose
(provided by the Monitor) . It accesses them via addresses in memory locations
and 46,
8
8
MOV
JSR
@#44,-(SP)
R5,@(SP) +
;0R MOV @#46,-(SP)
5-7
The driver must also ensure that the start addresses are set into the correct
locations (44_ and 46.,) .
8 o
At its final interrupt, the driver saves the contents of Registers 0-5 before
returning control to the calling program completion return.
3.1.5 Returns From Driver
As shovm in the example in Section 5-3.1.3, the driver returns control to the
calling program immediately after the JSR as soon as it has set the device in
motion. The program can wait or carry out alternative operations until the driver
signals completion by returning at the address specified (i.e., RETURN above).
Prior to this, the program must not attempt to access the data being read in, nor
refill a buffer being written out.
The program routine beginning at address RETURN varies according to the device
being used. In general, the driver has given control to the routine for one of two
reasons; either the function has been satisfactorily performed, or it cannot be
carried out due to some hardware failure with which the driver is unable to cope,
though the program may be able to do so. In the latter case, the driver uses
the STATUS word in the program list to show the cause:
Bit 15 = 1 indicates that a device or timing failure occurred
and the driver has not been able to overcome this,
perhaps after several attempts.
Bit 14 = 1 shows that the end of the available data has been
reached.
The driver places in R0 the contents of its first word as a pointer to the
parameter table (see Section 5-3.1.2).
Possibly, the driver has transferred only some of the data requested. In this
case, it shows in the RESERVED word of the program list a negative count of the words
not transferred in addition to setting Bit 14 of the STATUS word. As mentioned in
the note in Section 5-3.1.2 , this applies only to non-bulk storage devices. The
drivers for DECtape or disks* always endeavor to complete the full transfer, even
beyond a parity failure, or they take more drastic action (see Section 5-3.1.6).
^This includes RFll Disk; although this is basically word-oriented, it is assumed
to be subdivided into 64-word blocks.
5-8
It is thus the responsibility of the program RETURN routine to check the informa-
tion supplied by the driver in order to verify that the transfer was satisfactory
and to handle the error situations appropriately.
In addition, the routine must contain a sequence to take care of the Processor
Stack, Registers, etc. As noted earlier, the driver takes the completion return
address after an interrupt and saves Registers jli-5 on the stack above the
Interrupt Rettirn Address and Status. The program routine should, therefore, contain
some sequence to restore the processor to its state prior to such interrupt, e.g.,
using the same Restore subroutine illustrated earlier:
MOV §#46,- (SP) ;CALL REGISTER RESTORE
JSR R5,@(SP) +
RTI ; RETURN TO INTERRUPTED PROGRAM
3.1.6 Irrecoverable Errors
All hardware errors other than those noted in the previous section cannot normally
be overcome by the program or by the driver on its behalf. Some of these could be
due to an operator fault, such as not t\irning on a paper tape reader or not setting
the correct unit number on a DECtape transport. Once the operator has rectified
the problem, the program could continue. Other errors, however, require hardware
repair or even software repair, e.g., if the program asks for Block 2000 on a device
having a maximum of 1000. In general, all these errors result in the driver placing
identifying information on the processor stack and calling lOT to produce a trap
through location 34 .
Under DOS/BATCH, the Monitor provides a routine to print a teleprinter message when
this occurs. In a stand-alone environment, the program using the driver must
itself contain the routine to handle the trap (unless the user wishes to modify the
driver error exits before assembly) . The handler format depends upon the program.
The following format takes advantage of the information supplied by the driver:
Stored by lOT call
Generally unique to driver
1 » Recoverable after Operator Action
3 = No recovery
Such as content of Driver,
Control Register, Driver Identity,
etc.
As a rule, the driver expects a return following the lOT call in the case of recoverable
errors but contains no provision for an lOT call following a return from irrecoverable
errors .
5-9
(SP)
Return Address
2
(SP)
Return Status
4
(SP)
Error No. Code
5
(SP)
Error Type Code:
6
(SP)
Additional
Information
3.1.7 General Comment
The source language of each driver has been written for use with DOS/BATCH and
contains some code which is not accepted by the Paper Tape Software PAL-llR, in
particular, .TITLE, .GLOBL, and Conditional Assembly directives. Such statements
should be deleted before the source is used. Similarly, an entry in the driver
table gives the device name as .RAD 50 'DT' to obtain a specifically packed format
used internally by DOS/BATCH. If the user wishes to keep the name, for instance,
for identification purposes as discussed in Section 5-3.3, .RAD50 might easily
be changed to .ASCII without detrimental effect, or it might be replaced with
.WORD 0.
3.2 DRIVERS ASSEMBLED SEPARATELY
Rather than assemble the driver with every program requiring its availability, the
user may wish to hold it in binary form and attach it to the program only when
loaded. The only requirement is that the start address of the driver should be
known or be determinable by the program.
The example in Section 5-3.1.2 showed that the Interrupt Servicing routine can be
accessed through an offset stored in the Driver Table .^ The same technique can be
used to call the setup routines, as these also have corresponding offsets in the
Table, as follows:
DRIVER+7 Open^
+10 Transfer
+11 Close
+12 Special Functions^
The problem is the start address. There is the obvious solution of assembling the
driver at a fixed location so that each program using it can immediately reference
the location chosen. This ceases to be convenient when the program has to avoid
the area occupied by the driver. A more general method is to relocate the driver
as dictated by the program using it, thus taking advantage of the position-independent
nature of the driver. The Absolute Loader, described in the Paper Tape Software
Handbook (DEC-11-XPTSA-A-D) , provides the capability to continue a load from the
point at which it ended. Using this facility to enter the driver immediately
following the program, the program might contain the following code to call the
subroutine to perform the transfer illustrated in Section 5-3.1.3.
'^If the routine is not provided, these are 0.
5-10
MOV
ADD
MOV
ADD
PC,R1
#PRGEND-.,R1
PC,R0
#TABLE+12-.,R0
;GET DRIVER START ADDRESS
GET TABLE ADDRESS
AND SET UP AS SHOWN
...IN SECTION 5-3.1.3
CMP
MOV
CLR
MOVE
'add
JSR
-(R0),-(R0)
R0,@R1
-(SP)
10 (Rl) ,@SP
(SP)+,R1
PC,@R1
FINAL POINTER ADJUSTMENT
STORE IN DRIVER LINK
GET BYTE SHOWING. . .
. . .TRANSFER OFFSET
COMPUTE ADDRESS
GO TO DRIVER
PGREND:
.END
This technique can be extended to cover situations in which several drivers are
used by the same program, provided that it takes account of the size of each
driver (known because of prior assembly) and that the drivers themselves are always
loaded in the same order.
For example, to access the second driver, the above sequence would be modified to:
MOV
ADD
ADD
PC,R1
#PRGEND-.,R1
#DVR1SZ,R1
;GET DRIVER 1 ADDRESS
;SET TO DRIVER 2
DVRlSZ=n
PRGEND :
.END
An alternative method may be to use the MACRO Assembler in association with the
Linker program LINK, both of which are available through the DECUS Library. The
start address of each driver is identified as a global. Any calling programs need
merely include a corresponding .GLOBAL statement, e.g., .GLOBL DT.
3.3 DEVICE-INDEPENDENT USAGE
The drivers are assigned for use in a device- independent environment, i.e., one
in which a calling program need not know in advance which driver has been associated
with a table for a particular run. One application of this type might be to allow
line printer output to be diverted to some other output medivim because the line
printer is not currently available. Another might be to provide a general pro-
gram to analyze data samples although these on one occasion might come directly
5-11
from an Analog-to-Digital converter and on another be stored on a DECtape because
the sampling- rate was too high to allow immediate evaluation.
Programs of this type should be written to use all the facilities that any
one device might offer, but not necessarily for each device. For instance, the
program should ask for start-up procedures because it may sometime use a paper
tape -punch which provides them, even though it may normally use DECtape which
does not. As noted in paragraph 5-2.2.1, the driver table contains an indication
of its capabilities to handle this situation. The program can thus examine the
appropriate item before calling the driver to perform some action. As an example,
the code to request start-up procedures might be (assuming R0 already set to
List Address) :
GET DRIVER ADDRESS
BIT 7 SHOWS
...OPEN ROUTINE PRESENT
STORE TABLE ADDRESS
BUILD ADDRESS
; ...OF THIS ROUTINE
; . . .AND GO TO IT
; FOLLOWED POSSIBLY BY
;WAIT AND COMPLETION
; PROCESSING
; RETURN TO COMMON OPERATION
MOV
#DVRADD,R1
TSTB
2(R1)
BPL
NOOPEN
MOV
R0,§R1
CLRB
-(SP)
MOVB
7(R1),@SP
ADD
(SP)+,R1
JSR
PC,@R1
NOOPEN?
Similarly, the indicators show whether the device is capable of performing input
or output, or both; whether it can handle ASCII or binary data; whether it is a
bulk storage device capable of supporting a directory structure or is a terminal-
type device requiring special treatment. Other table entries show the device
name as identification and the number of words the device might normally expect
to transfer at a time (in 16-word units) . All of the information can be readily
examined by the calling program, thus enabling the use of a common call sequence
for any I/O operation, as illustrated in the example on the following page.
5-12
MOV
#DVRADR,R5
JSR
R5 , lOSUB
BR
WAIT
• WORD
10
.WORD
103
.WORD
BUFFER
.WORD
-256.
.WORD
404
.WORD
RETURN
.WORD
WAIT:
SET DRIVER START
CALL SET UP SUB
SKIP TABLE FOLLOWING ON RETURN
TRANSFER REQUIRED
BLOCK NO.
BUFFER ADDRESS
WORD COUNT
READ FROM UNIT 1
;EXIT ON COMPLETION
; RESERVED
/•CONTINUE HERE...
lOSUB:
MOV
MOV
TST
MOV
ADD
CLR
MOVB
ADD
JSR
RTS
@SP,R0
R5,R1
(Rl) +
@R1,R1
R0,R1
-(SP)
@R1,@SP
R0,@SP
PC,§(SP) +
R5
PICK UP DRIVER ADDR
SET UP POINTER TO LIST
BUMP TO COLLECT CONTENT
ROUTINE CHECKS ON DEVICE
. . .CAPABILITY USING Rl
...TO ACCESS LIST AND
. . .R0 THE DRIVER TABLE
IF O.K...
GET ROUTINE OFFSET
;USE IT TO BUILD
; . . .ENTRY POINT
;CALL DRIVER
;EXIT TO CALLER
The calling program, or a subroutine of the type just illustrated, may take
advantage of a feature mentioned earlier; the fact that when a driver is in use,
its first word is non-zero. The driver itself does not clear this word except
in special cases shown in the description for the driver concerned. If the pro-
gram itself always ensures that the first word of the driver is set to zero between
driver tasks, then this word foirms a suitable driver-busy flag. Under DOS, the
program parameter list is extended to allow additional words to provide linkage
between lists as a queue in which the list indicated in the driver's first word
is the first link.
The preceding paragraphs indicate possible ways of incorporating the available
drivers into the type of environment for which they were designed. The user should
carefully read the more detailed description of the driver structure in Chapter 5-4,
and the individual driver specifications before determining the final form of his
program.
5-13
A word of warning is appropriate here. Although most drivers set up an operation
and then wait for an interrupt to produce a completion state, there are some cases
in which the driver can finish its required task without an interrupt, e.g.,
"opening" a paper tape reader involves only a check on its status. Moreover,
where "Special Functions" are concerned, the driver routine may determine from
the code specified that the function is not applicable to its device, and therefore,
have nothing to do. In such cases, the driver clears the intermediate return
address from the processor stack and immediately takes the completion return.
Special problems can arise, however, if the driver concerned is servicing several
tasks, any of which can cause a queue for the driver's services under DOS/BATCH.
To overcome these problems, the driver expects to be able to refer to flags outside
the scope of the list so far described. This can mean that a program using such
a driver may also need to extend the list range to cover such possibilities.
Particular care should be exercised in such cases.
5-14
PART 5
CHAPTER 4
I/O DRIVERS WITHIN THE
DOS/BATCH OPERATING SYSTEM
The principal function of an I/O driver is to satisfy a Monitor processing routine's
requirement for the transfer of a block of data in a standard format to or from
the device it services. This involves setting up the device hardware registers to
cause the transfer and gaining control under the interrupt scheme of PDP-11, making
allowance for peculiar device characters (e.g., conversion to or from ASCII if
some special code is used) .
The I/O driver must also include routines for handling device start-up or shut-
down such as punching leader or trailer, and for making available to the user
certain special features of the device, such as rewind of magtape.
4.1 DRIVER STRUCTURE
In order to provide a common interface to the Monitor, all drivers must begin with
"a table of identifying information as follows:
DVR:
BUSY FLAG (initially 0)
FACILITY INDICATOR (expanded below)
Offset to
Interrupt Routine*
Standard Buffer Size
in 16-word Units.
Offset to
OPEN Routine*
Priority for
Interrupt Service*
Offset to
CLOSE Routine*
Offset to
Transfer Routine*
Space
Offset to
Special Functions*
DEVICE NAME (Packed Radix- 50)
Offsets marked * enable the calling routine
to indicate the routine required. The offsets
are considered to be an unsigned value to be
added to the start address of the driver. This
may mean that with a 256-word maximum, the
instruction referenced by the offset is a JMP or BR
(routine) .
5-15
The table should be extended as follows if the device is file-structured i
BLOCK USED AS MASTER FILE DIRECTORY
POINTER TO BIT-MAP IN MEMORY
Unit
Similar Bit-Map
Pointers for
Multi-Unit Devices
The driver routines that set up the transfer and control under the interrupt follow
the table.
Bits in the Facility Indicator Word define the device for Monitor reference:
SPECIAL STRUCTURES
GENERAL STRUCTURE
File
Structured
Device -i
DEC tape
(or simil-
arly
reversible) _
Magtape
15 14 13 12 11 10
t t t t t t T T
I Reserved Reserve
Variable length
record bit
f
t
Multi-User
Output Device
Input Device
Binary Device
ASCII Device
Contains SPECIAL
Contains CLOSE
Contains OPEN
"Terminal"
Device
Multi-unit System
type devices (i.e., RK disk)
4.2 MONITOR CALLING
When a Monitor I/O processing routine needs to call the driver, it first sets up the
parameters for the driver operation in relevant words of the appropriate DDB^, as
illustrated in the following table.
Dataset Data Block - a 16-word table which provides the main source of communica-
tion between the Monitor drivers and a particular set of data being processed on
behalf of a using program.
5-16
DDB:
specizUj function code
DEVICE BLOCK NUMBER
MEMORY BLOCK ADDRESS
WORD COUNT (2'S COMPLEMEJJT)
TRANSFER FUNCTIONS (expanded below)
COMPLETION RETURN ADDRESS
(DRIVER WORD-COUNT RETURN) Set to Zero
(User Call Address)
(User Line Address)
The relevant content of the Transfer Function word is as follows:
EOF
or
EOD
TT Echo Control
15
T
I 141 13 I
12 11 10
reserved
Used by Driver DEC tape
to indicate reverse
Hardware Parity . DEVICE
Fail , UNIT
(reserved)
Open vs.
Closed
0=ASCII
l=Binary
Transfer OUT
Transfer IN
Provided that the Facility Indicator in the Driver Table described above shows that
the driver is able to satisfy the request, according to the direction and mode and
the service required, the Monitor routine places in Register 1 the relative Byte
address of the entry in the Driver Table containing the offset to the routine to
be used (e.g., for the Transfer routine, this would be 10). The Monitor routine
then calls the Driver Queue Manager, using a JSR PC, S.CDB instruction.
The Driver Queue Manager refers to the Busy Flag (Word of the driver table) to
assure that the driver is free to accept the request. If the Busy Flag contains 0,
the Queue Manager inserts the address of the DDB from Register and jumps to the
start of the routine in the driver using Register 1 content to evaluate the address
required. If the driver is already occupied, the new request is placed in a queue
linking the appropriate DDB's for datasets waiting for the driver's services. It
is taken from the queue when the driver completes its current task. (This is done
by a recall to the Queue Manager from the routine just serviced, using JSR PC,S.CDQ)
5-17
On entry to the Driver Routine, therefore, the address following the Monitor routine
call remains as the "top" element of the processor stack. It can be used by the
driver in order to make an immediate return to the Monitor (having initiated the
function requested) , using RTS PC. It should also be noted that the Monitor
routine saves register contents if it needs them after the device action. The
driver may thus freely use the registers for its own operations.
When the driver has completly satisfied the Monitor request, it should return
control to the Monitor using the address set into the DDB. On such return.
Register must be set to contain the address of the DDB just serviced and since
the return will normally follow an interrupt. Registers 0-5 at the interrupt must be
stored on top of the stack.
4.3 DRIVER ROUTINES
4.3.1 TRANSFER
The sole purpose of the TRANSFER routine is to set the device in motion. The
information needed to load the hardware registers is available in the DDB, whose
address is contained in the first word of the driver. Conversion of the stored
values is the function of the routine. It must also enable the interrupt; however,
it need not set the interrupt vectors as these are preset by the Monitor when the
driver is brought into core. After the TRANSFER routine has activated the device,
the routine returns to the calling processor by an RTS PC instruction.
4.3.2 Interrupt Servicing
The form of this routine depends upon the nature of the device. In most drivers
it falls into two parts, one for handling the termination of a normal transfer and
the other to deal with reported error conditions.
For devices which are word or byte-oriented, the routine must provide for indi-
vidual word or byte transfers, with appropriate treatment of certain characters
(e.g., TAB or Null) and for their conversion between ASCII or binary and any
special device coding scheme, until either the word count in the DDB is satisfied
or an error prevents this. On these devices, the most likely case for such error
is the detection of the end of the physical medi\im; the treatment for the error
varies according to v^ether the device is providing input or accepting output-
The calling program usually needs to take action in the former case and the driver
should merely indicate the error by returning the unexpired portion of the word
count in DDB Word 7 on exit to the Monitor. Output End of Data requires operator
5-18
action. ~ To obtain this, the driver should call the Error Diagnostic Print routine
within the Monitor by:
MOV DEVNAM,-(SP) ;SHOW DEVICE NAME
MOV #402,- (SP) ;SHOW DEVICE NOT READY
lOT ;CALL ERROR DIAGNOSTIC PRINT ROUTINE
On the assumption that the operator will reset the device for further output and
request continuation, the driver must follow the above sequence with a Branch or
Jvunp to resume the transfer . '
Normal transfer handling on blocked devices (or those like RFll Disk which are
treated as such) is simpler since the hardware takes care of individual words or
fcytes and the interrupt only occurs on completion.
Errors that indicate definite hardware malfunctions must generate diagnostic
messages to the Operator, The only recourse is to start the program over, after
the malfunction has been corrected.
There are some errors which the driver can attempt to overcome by restarting the
transfer. Device parity failure on input is a common example. If one or more
retries are unsuccessful, the driver should normally allow programmed recovery
and indicate the error by Bit 15 of DDB word 5. Nevertheless, because the pro-
gram may try to process the data despite the error, the driver should attempt to
transfer the whole block requested if this has not already been effected. The
remaining forms of errors must be processed according to the type of recovery
deemed desirable.
Whether the routine uses processor registers for its operation depends on con-
siderations of the core space saved against the time taken to save the user's
contents. However, on completion (or error return to the Monitor) , the calling
routine expects the top of the stack to contain the contents of Registers 0-5
and Register to be set to the address of the DDB just serviced. The driver
must, therefore, provide for this.
4.3.3 OPEN
This routine need be provided only for those devices that require some hardware
initialization. It should not normally appear in drivers for devices used in a
file oriented manner. The presence of the routine must be indicated by Bit 7
in the driver table Facility Indicator.
5-19
The OPEN routine may vary according to the transfer direction of the device. For
output devices, the probable action required is the transmission of appropriate
data, e.g., CR/LF at a keyboard terminal, form-feed at a printer, or null characters
as punched leader code, and for this a return interrupt is expected. The OPEN
routine should then be some\^at similar to the TRANSFER routine in that it sets
the device going and makes an interim return via RTS PC, waiting until completion
of the whole transmission before taking the final return address in the DDB.
An input OPEN may consist of just a check .on the readiness of the device to provide
data when requested. In this case, the desired function can be effected without any
interrupt wait. The routine should, therefore, take the completion return immediately.
Nevertheless, it must ensure that the saved PC value on top of the stack from the call
to S.CDB is appropriately removed before exit. In the case of drivers which can service
only one dataset at a time (i.e.. Bit of their Facility Pattern word is set to 0)
and can never be queued, a TST (SP)+ instruction can effect this. However, a multi-
user driver must allow for the possibility that it may be recalled to perform some
new task waiting in a queue. This condition exists if the byte at DDB-3 is non-zero.
In this case, the driver must simulate the interrupt expected by the completion
process. This is accomplished by inserting a PS word on the stack above the return
address supplied by the JSR of the Open request. A possible sequence for the
interrupt simulation is illustrated below.
EXIT!
MOV
DRIVER, R0
MOV
(SP) + ,R5
TSTB
-3 (R0)
BEQ
EXIT
MOV
§#177776, -(SP)
MOV
R5,-(SP)
SUB
#14, SP
JMP
@1O(R0)
;PICK UP DDB ADDRESS
;SAVE INTERIM RETURN
;COME FROM QUEUE?
IF SO, STORE STATUS
...& RETURN
DUMMY SAVE REGS
4.3.4 CLOSE
The CLOSE routine is like the OPEN routine, in that it should provide for the
possibility of some fomn of hardware shut-down, such as the punching of trailer code
and that it is not necessary for file-structured devices. Moreover, it is likely
to be a requirement for output devices only. If it is provided. Driver Table
Facility Indicator (Bit 6) must be set.
5-20
Again, the probable form is initialization of the, hardware action required, with
immediate return via RTS PC and eventual completion return via the DDB-stored
address.
4.3.5 SPECIAL
This routine may be included if either the device itself contains the hardware to
perform some special function or there is a need for software simulation of each
hardware on other devices, e.g., tape rewind; it should not be provided otherwise.
Its presence must be indicated by Bit 5 of the Facility Indicator.
The function itself is stored by the Monitor as a code in the DDE. When called,
the driver routine must determine whether such function is appropriate in its case.
If not, the completion return should be taken immediately with prior stack clearance,
as discussed under OPEN. For a recognized function, the necessary routine must be
provided. Its exit method depends upon the necessity for an interrupt wait.
4.4 DRIVERS FOR TERMINALS
The rate of input from terminal devices normally reflects the typing skill of the
operator. For both input and output, the amount of data to be transferred on each
occasion may be a varying length, i.e., a line rather than a block of standard size.
Furthermore, echoing input may conflict with interrupting output. As a result,
drivers for such devices demand special treatment.
Normal output operation, i.e., .WRITE by the program, is handled by the Monitor
Processor. On recognizing that the device being used is a terminal, as shown by Bit
8 of the facility indicator, this routine always causes a driver transfer at the end
of the user line, even though the internal buffer has not been filled. The driver,
however, is given the whole of a standard buffer, padded as necessary with nulls.
Provided the driver can ignore these, the effect is the suppression of trailing nulls.
Input control remains the driver's responsibility since overcoming the rate problem
requires circular buffering within the driver. This circular buffering feature
allows the user type-ahead facilities. A sxibsequent input request may then be
satisfied by data already in core. If the data is sufficient to fill the Monitor
buffer, the driver awaits the next request before further transfer. If this is
insufficient, the driver should operate as any other device and use subsequent
interrupts to satisfy the Monitor's requests. Since the driver must stop any trans-
fer at the end of a line in normal operation, in order to allow the Monitor to con-
tinue, the driver must simulate the filling of the buffer by null padding. If the
user requests .TRAN's which are not line oriented, the buffer size varies from the
standard and the driver assumes the program requires a complete buffer before
return.
5-21
PART 5
CHAPTER 5
SAMPLE LINE PRINTER DRIVER LISTING
The following is a sample listing of a DOS/BATCH Device Driver. The actual driver
is the LPll Line Printer Driver (for device name LP:).
I
2
3
A
5
6
7
8
9
10
U
12
13
14
15
16
17
la
19
20
21
22
23
24
29
26
27
28
29
30
31
32
33
34
39
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
91
LPTYP
000001 UPU
000012 8KIP2
L811
SPHEAO
3K1F2
WIOTH
000000 R0
000001 Rl
000002 R2
000003 R3
000004 R4
000005 R5
000006 SP
000007 PC
000402 A002
000044 S.HSAV
OiBITAl EQUIPMENT CORPORATION, MAVNARD, MASSACHUSETTS 01
COPYRIGHT! 1»73
DI6ITAU EQUIPMENT CORPORATION ASSUMES NO RESPONSIBILITY
FOR THE USE OR RKUIABILITY OF ITS SOFTWARE ON EQUIPMENT
WHICH IS NOT SUPPLIED BY DIGITAL EQUIPMENT CORPORATION,
VERSION NUMB£RI V13.01
DATEOI MARCH 9, 1973
DEVICE DRIVER FOR THE LPU/LSU LINE PRINTERCS)
DRIVER PARAMETERIZATION SYMBOLS
LPllf LS11» WIDTH, SPACES, SPREAD
IF
ENOC
IF
TITLE
IFF
IF
TITLE
IFF
MERROR
ENOC
ENOC
;LPTYP=i2f if I.P11
;LPTYP=1 if LSll
; DEFAULT IS
NOF, LPTYP
EO,LHTYP
DV,LP0
1
12
Ea,<LPTYP-l>
DV.LP*
1
1
13
;UNSUPP0RTE0 LINE PRINTER
IFNDF WIDTH
I 80. COLUMN PRINTER DEFAULT
ENOC
X0
XI
X2
X3
X4
X5
X6
X7
402
44
I DIAGNOSTIC MESSAGE CODE
I REGISTER SAVE (MONITOR SUPPORT
5-22
UV,LP0 HACRU V06*id9 09«JAN«74 12155 PAGt; 5
1
3
4
5
6
7
8
9
10
11
12 000192
13
14 00003
19 00004
16 00009
17 00006
18 00007
19 00010
20 00011
21
22 00012
23
24
29
26 00013
27 00014
28
29
30
31
32
33 00016
34 00020
39 00022
36 00024
37 00026
38 00030
39 00032
40
41 00034
42
43
44
49 00034
00039
46
47
48
49
90
91
I
000000 000000 LPt
322
000
003
U0
200
036
060
036
000
000
046600 tP.NAnt
000200 UP*TRP
177914 IP.CSH
177916 LP.ueK
000120
000133
000000
000000
000000
000000
000000
LPtSUt
UPPCASI
ovpknti
LPiUlNI
i.P«8K8l
UPtTCti
UPiBAUt
LPtTOKI
019
014
•OUOBL UP
•lOENT /i3,01/
D08«ll DEVICE 0RIV|R«8 STANDARDIZED INTERFACE
UP.FU6I
• MORD
• IFOF
.BYTE
• ENDC
•IFNDF
• BYTE
.ENDC
.BYTE
.BYTE
• BYTE
.BYTE
.BYTE
.BYTE
.BYTE
.IF
• BYTE
.IFF
.BYTE
.ENDC
.BYTE
.RAD90
i
■
.WORD
• WORD
• WORD
• WORD
.WORD
• WORD
.WORD
• IFOF
.BYTE
• ENDC
.BYTE
.EVEN
.IFDF
• WORD
• ENDC
LSll*SPREAO
362
USll&SPREAD
322
t USER'S DOB POINTER
f FACIUITIES INDICATOR
I FACILITIES INDICATOR
I SPECIAL STRUCTURES, NONE
<^WIOTH'»'37>/40» t STANDARD BUFFER SIZE
LP.INT-UP I INTERRUPT ENTRY OFFSET
; INTERRUPT PRIORITY 4'
I OPEN ENTRY OFFSET
t TRAN ENTRY OFFSET
I CLOSE ENTRY OFFSET
200
LP.OPN-UP
LP.TKN^UP
UP.CU^«LP
EQfUPTYP
LP.SPC-UP
/LP^
200
177914
177916
WIDTH
133
000040 UP.UOW ■
tsu
21
LSll^SPREAD
40
; SPECIAL ENTRY OFFSET
; SPARE
t DEVICE DRIVER'S NAME
f INTERRUPT VECTOR'S ADDRESS
I COMMAND/STATUS REGISTER
; DATA BUFFER REGISTER
f THIS WORD IS SET BY THE INIT|A
; SET TO THE HIGHER PRINT LIMIT
I SET TO TRUE WHEN OVER PRINTING
I ALREADY SENT (CHARACTERS)
t BLANK POSITIONS COUNTER
t TRANSFER CHARACTER COUNT
t BUFFER ADDRESS POINTER
I COMMAND DEVICE TO TOP-OF-FORM
I COMMAND DEVICE TO ON-LINE
I CR, FF
I CHARACTER ELONGATION FLAG
I PRINTABlLITYr LOWER LIMIT
5-23
I
2
;
OPhN PROCESSUR
3 0000^6
tp,
.QPNI
4
;
CU08E PROCESbOR
5 000046
IP.
iCU8J
a 000036
004767
000454
JSR
PCfUP.STS
7 000042
062/01
177772
ADO
<*UP,TOP-i»Rl
8 000046
010167
177760
MOV
RliUP.BAO
9
• IFOF
USll
10
MOV
#-3,UP,TCT
11
,ENOC
12
• IF NOP
USll
13 00052
010267
177752
MOV
R2,UP,TCT
14
• ENOC
15
• IPOF
USU&SPREAO
16
CUR
UP. FUG
17
,ENQC
18 000^6
000414
BR
UP. INT
19
20
• IPOF
USll^SPREAO
21
22
t
SPECIAU
PROCESSOR
23
LP.
• SPCI
24
MOV
2CR0J,R1
25
CMP8
»lf (Rn
26
bUi.
UP.S00
27
MOV
2CRU,UP.FUG
28
UP.
iS001
JMP
#14CR0)
29
.ENOC
30
31
;
IRAN PROCESSOR
32 000e»0
UP.
iTKNI
33 00060
004767
000432
JSR
PCUP.STS
34 00064
016700
177710
HOV
UPpR0
35 0.0070
016067
000006
177734
MOV
6CR0]|UP«BA.D
36 00076
016067
000010
177724
MOV
10(R0)rUP.TC
37 00104
006367
177720
ASU
UP.TCT
I SIMUUATI INTERRUPT
I Rl ■ PC (BY UP.STS)
I INTERNAU BUFFERtS AOORESS
; INITIAUliE TRANSFER COUNT
> R2 ■ -2 (BY UP.STS)
I INITIAUUE EUONGATION fuag
f OISPATCH INTERNAU BUFFER
f Rl • FUNCTION BUOCK'S AOORESS
f UINE EUONGATION FUNCTION ?
; NOf IGNORE
; ENABUE/OiSABUe EUONGATION
f EXIT VIA COMPUETION RETURN
f SIMUUATE an INTERRUPT
; R0 i USER IS DOB ADDRESS
I RETAIN BUFFER'S ADDRESS
t RETAIN DOB'S BYTE COUNT
5-24
1
2
3 000U0
4 000U0
5 000U6
6 000U0
7 000U4
8 0001<i0
9 0001.32
10 00144
11 00liJ6
12 00140
U 00142
14 00146
15 00lt3i2
16 001d6
17 001^0
18 00162
19 00166
20
21
22
23
24
29 00170
26 00174
27 00176
28 00200
29 00202
30 00210
31 00212
32 00214
33 00216
34 00220
36 00226
36 00230
37 00234
38 00236
39 690236
40
41 00242
I
LP.INTI
042737
00'0100
177814
002002
000167
000394
005767 IP, 101
177700
001452
010446
010346
010246
010146
016704
177660
016703
177652
016702
177654
112201 LPa00I
001426
120127 UP. 1011
000040
002442
INTERRUPT PROCESSOR CViA INTERRUPT VECTOR AT 200)
8IC #100i##|.P,CSR t DISABLE INTERRUPT
120167 UP.I02S
177624
002111
005203 LPfl03t
003016
032737 l.P,I04S
100200
177S14
100531
001520
005304
100404
112737
000040
177516
000763
110137 LP,J05S
177516
005004 |.P,I06;
UPtONPJ
006267 UP.TRTJ
177566
001345
BGE IP, 10
4MP LP.EHr
TST UP.TCT
8EQ LP, DONE
MOV R4,»tSP)
MOV R3,*UP)
MOV R2,-tSP)
MOV R1,-(.SP)
MOV LP,BKS,R4
MOV LP,HN,R3
MOV LP,8AD,R2
M0V9 (R2)+,R1
SEQ LP.ONp
CMP9 R1,#LP,L0W
bUT LP,n0
•IFOF SPACES
BGT LP. 1^2
INC R4
eR Lf.TRT
.ENOC
CMPti R1,UPPCAS
BOE LP.Ila
INC R3
8GT LP.DNp
BIT #100200, ##LP.CSR
bMI LP. 122
BEQ LP, 120
DEC R4
BMI LP. 108
MOVE* #40,<»l»LP.D8R
BR LP, 103
M0V8 Rl,<»*»LP.DBR
CLH R4
INC LP,Tt;T
BNE L^,I00
SEGREGATe ERRORS
ENTER ERROR PROCESSOR
ANY CHARACTERS REMAINING ?
NO, LINE COMPLETED
SAVE REGISTERS
R4 » BLANK COUNTER
R3 • PRINT POSITION
R2 « BUFFER POINTER (ADDRESS)
♦♦♦ ACCESS CHARACTER ♦♦*
NULL (0) IGNORED
PRINTABILITY CHECK
EXCEEDS LOWER LIMIT
VALID CHARACTER, SO FAR
BLANK t40) ISOLATED, COUNT
ACCESS NEXT CHARACTER
PRINTABILITY CHECK
EXCEEDS UPPER LIMIT
PRINTER'S WIDTH EXCEEDED ?
YES, 00 NOT PRINT
ACCESS ERROR/READY STATUS
ERROR Indication
NOT READY INDICATION
DECREMENT BLANK COUNTER
NOT PROCESSING BLANKS
BLANK/HTAB EXPANSION PERFORMED
CONTINUE PENDING COMPLETION
*♦* PRINT CHARACTER *♦*
INSURE NQ BLANKS PENDING
INCREMENT BUFFER'S CHARACTER
COUNTER, ANY MORE 7
YES
5-25
I
2
1
\
•
HN£ COMPLETED
3
4 000244
105737
177514
?
TSTa
#«»LP«CSK 1
5 000250
100103
BPL
LP.I21 ;
6 000252
004567
000260
LP,
ONtJ
JSR
Ka,LP.SfcT >
7 000256
013746
000044
LP.
DONI
MOV
#«S,KSAV#'*CSP) }
8 000262
004636
JSH
R5,PCSP)* >
9 000264
016700
177510
MOV
LP»R0 I
10 00270
000170
000014
JMP
#14(K0) 1
U
12 00274
120127
000011
UP,
I10J
CMPa
Rl,«ll r
13 00300
001010
BNE
LP, 113 ;
14
1
13
;
HORIZONTAL TAB SI
16
1
17 00302
016746
177510
MOV
LP,SiZ»-CSP) 1
16
• IFOF
LSllSSPRtAO
19
TST
LP.FLG ;
20
6£Q
LP.IU »
21
A3R
(SP) 1
22
.£NOC
23 00306
060316
LP
.1111
AQU
R3rCSP) r
24
.XFDF
LSll48PRtA0
25
BG£
LP.U2 i
26
CLN
LP.TLT I
27
bR
LP. ONE 1
28
.ENO'C
29 00310
060416
LP
.lUl
AQQ
R4,(6P) ;
30 00312
052716
17777^
618
#177770» CSP) »
31 00316
102604
bUB
(5P)t,R4 }
32
33 00320
000746
BR
LP.TKT }
34
> DEVICE BUSY ?
YES
RESTORE TEMPORARIES
SAVE REGISTERS
R0 * USER<S DDB ADDRESS
EXIT VIA COMPLETION RETURN
HORIZONTAL TAB (11) 1
NO
MULATION VIA BLANKS
PRINTER'S MAX WIDTH
ELONGATION ?
NO
(PRINTER'S HlOTH)/2
• PRINT POSITION
NOT EXCEEDED PRINTER'S »JlDTH
ELONGATION LiNE TERMINATION
EXIT
♦ BLANK COUNTER
( MODULO 8 ) - 8
•♦■ BLANK COUNTER
• BLANK COUNTER
ACCESS NEXT CHARACTER
5-26
1 ^my^^ i'dv>X27 lp.ii«m
A 000340 001014
4 000342 005767
177404
5 000336 001021
6 000340 016703
177458
7 000344 005403
9
10
11
12
13
14
15
16
17
la
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
00346 UPtlXXI
00346 000732
003t>0 lP,I14t
IPaVYS
003d(a 120127
000022
00334 001016
00356 012701
000012
00362 120127 UPW1&?
000012
00366 002411
00370 001404
00372 120127
000013
00376 001717
00400 000400
00402 UP,I16i
00402 0167^3
177410
00406 005403
00410 000674
CMPa
BGT
TST
BN£
NOV
NEG
• IFOF
TST
ASR
MOV
• ENQC
BR
• IFOP
TST
dlQ
CMPd
BEQ
• ENOC
QMPB
BNE
MOV
CMP9
BIT
BEQ
CMP8
BEti
BR
MOV
NEG
• IFOF
TST
BEQ
ASR
MOV
• ENOC
BR
Rl,#l5
UP,I14
IP,I15
QVPRNT
ip.ne
UP.SJIZ,R3
R3
USlliSPRtAD
LP.FUG
R3
RSft^'.FlG
lP,IkJ6
usu&spreao
LP, FUG
LP.IYY
Rlf#ia
LP, 104
Rlf#22
LP,U7
#3KlP2fRl
Rlr#l2
LP,Il7
LP.ne
Rli#t3
LP.DNP
LP.ne
LP,SUfR3
R3
LSll&SPREAl)
LP.FLG
LP, 104
R3
R3,LH.PLG
LP, 104
t CARRIAGE-RETURN Cl5) ?
f NO, ABOVE
I HO, BELOW
I PRINT THE CARRIAGE-RETURN 7
I YES
> R3 • -C PRINTER'S WIDTH)
f
t ELONGATION ENABLED ?
f NO
t HALVE PRINTER'S WIDTH
; RE-INITIALIZE THE FLAG
; SUPPRESS CARRIAGE-RETURN
NO
SUBSTITUTE APPROPRIATE CHAR
LINEFEED (12) 7
NOf BELOW
YES
VERTICAL TAB (13) ?
YES, IGNORE IT I
NO, FORMFEED (14) ISOLATED
R3 • -( PRINTER'S WIDTH )
ELONGATION ENABLED 1
NO, PRINT CHARACTER
HALVE PRINTER'S WIDTH
RE-INITIALIZE THE FLAG
t PRINT THE CHARACTER
5-27
I iaBld4l2 012701 UP. 1171 HOV
Z 000416 I3a0667 BR
3 000420 120127 UP.lUt CMP8
000172
4 000424 003003 BQT
6 f
6 >
7 1
8 000426 042701 BIC
000040
9 000432 000661 BR
10 00434 120127 IP.IISI CMP8
000177
II 00440 001676 BEQ
12 004'»2 126727 CMP8
177352
000137
13 00490 101252 BHI
14 00452 fd^Q757 BR
15
16 00454 005303 UP. 1201 DEC
17 00456 005302 DEC
IB 00460 004567 UPtl2U JSR
000052
19 00464 052737 BIS
000100
177614
20 00472 000002 RTI
21
22 00474 005303 UPtl22l DEC
23 00476 005302 DEC
24 00500 016746 UP.tRKI MOV
177310
25 00504 012746 MOV
000402
26 00510 000004 XOT
27 00512 000167 JMP
177372
#40, Hi
UP. 103
Rlr#l72
I unprintabue# buank substitutio
I PRINT A BUANK
f UQWER CA9E AUPHABET ?
UP, 119 t EXCEEDS
UOWEK CASE TO UPPER CASE CONVERSION PERFORMED
#40,Rl I CONVERSION PERFORMED
UP, 103
R1,#177
UP.ONP
UPPCASi<*i37
UP. 11^3
UP. 117
R3
R2
R5,UP.S£T
I PRINT CHARACTER
1 RUBOUT Ci77) ?
I YES, IGNORED
f UPPER CASE PERMITTED ?
I YES, PRINT CHARACTER
f UNPRINTABUE, BUANK SUBSTITUTIO
f BACKUP PRINT POSITION
I BACKUP BUFFER POSITION
I RESTORE TEMPORARIES
#100,##UP.CSR f ENABUE INTERRUPT
R3
R2
UP,NAM,-CSP)
#A002,»»C5P)
UP. INT
; EXIT FROM INTERRUPT
t BACKUP PRINT POSITION
I BACKUP BUFFER POSITION
; DEVICE DRIVER'S MNEMONIC
1 MESSAGE CODE
f TRY AGAIN
5-28
1
2
3
4 000516
f *
UP.STSJ
INTEKRUPT SIMULATOR
012601
MOV
C3P3*,Rl
1 RETURN PC
5 000620
011646
MOV
(SP3r-CSP)
1 OLD PC
6 000922
005002
CLR
R2
t ADDRESS PS C-2)
7 000924
014266
000002
MOV
-CR2)»2CSP)
1 OLD STATUS
8 000630
013712
000202
MOV
#«LP.TRP*2,(R2)
r NEW STATUS
9 000534
10
11 00536
010107
MOV
Ri,pg
1 RETURN
010467
UP. Sin
MOV
R4,tP,BKS
1 RESTORE TEMPORARIES
177264
12 00542
010367
177256
MOV
R3,Uf.HN
f
13 00546
010267
177260
MOV
R2,UP,BA0
f
14 00562
016604
000010
MOV
10(8P3»R4
1 RESTORE REGISTER 4
15 00556
012666
000006
MOV
(SP)*,6CSP)
1 RETAIN RETURN ADORE
16 00562
012601
MOV
CSP)*,R1
f RESTORE REGISTERS
17 00664
012502
MOV
(3P)*,R2
1
18 00566
012603
MOV
CSP)*,R3
f
19 00570
000205
RTS
R5
1 EXIT SUBROUTINE
20
000001*
• END
5-29
OV.1,P0 MACrU V06»0i 09-JAN-74 12S55 PAGE U-1
SYMBOL TABLE
A002 i
000402
BF3HFT*
010000
BLANK i
000040
BSU8H •
000i;34
CR »
000015
DDBADRi
000006
OUBBLK*
000004
DDBCNT9
000010
QOBCRT*
000014
OOBOVA*
177776
t)DB3TS»
000012
OOBULA*
000002
DOBUNT*
000013
DITBFSi
000004
DITBMPi
000016
DITB5Y*
000000
DITFACi
000002
OITINT*
000005
DITMrD»
000014
OlTNAMi
000012
DnOPNn
000007
DiTPRIt
000006
OlTSPFi
000011
DITXFR»
000010
EMTINTI
000006
EMTRETi
000014
EMTVAL*
104000
EMTVEC*
000030
FTCOM •
000001
FTOOS «
000001
FTMUO «
000001
FTRPG «»
000001
FTRP031
000001
F001 •
001401
F002 •
001402
F003 ■
001403
F005 «
001409
F007 ■
001407
F011 ■
001411
F012 •
001412
F017 •
001417
F024 m
001424
F042 •
001442
F050 «
0014^0
F052 ■
.001452
KSBSiZ"
000400
LF •
000012
LP
000000KQ
LPTyP •
000000
LP. BAD
000032R
LP.BKS
000026R
LP, CIS
000036R
LP.CSRi
177514
LP.DBRi
177516
LP.ONfe
000292R
LP.ONP
000236R
LP. DON
000256R
LPrERR
000500R
LP. INT
000110R
LP.IXX
000346R
LP,I0
000124R
LP. 100
0001d6R
LP. 101
000162R
LP,I02
000170R
LP. 103
000176R
LP. 104
000202R
LP.I05
000230R
LP. 106
0002<i4R
LP. 110
000274R
LP. Ill
000306R
LP. 112
000310R
LP. 113
000322R
LP. 114
000350R
LP. IIS
000362R
LP. 116
000402R
IP. 117
000412R
LP, 118
000420R
LP. 1 19
000434R
UP. 120
000454R
IP.I21
0004t>0R
LP.I22
000474R
LP. LIN
000024R
LP. LOW*
000040
LP. NAM
000014R
LP.OPN
000036R
LP. SET
000536R
LP.srz
000016R
LP.ST8
000S16R
LP.TCT
000030R
LP.TOF
000034R
LP.TRN
000060R
LP.TRPt
000200
LP.TRT
000236R
LPIX •
000001
MSBSIZ"
001000
OVL006*
000002
OVL016"
000006
OVPRNT
000022R
OV10611
000012
OV2061»
000012
PATSIZ*
000030
PRI4 ■
000200
PRJ7 «
000940
PS •
177776
PSPRI0«
177437
RPBIT ■
004000
RP02SZ*
000020
RUBOUTt
000177
SKIP2 ■
000012
SMB3IZP
000040
STMA8KP
107070
S.RSAV*
000044
TABCH ■
000011
UPPCAS
000020R
V.CDB •
000050
V.COQ »
000052
V.6T8 •
000054
V.RLS •
0000d6
V.RRES*
000046
V.RSAVp
000044
V.SVT »
000040
V.XIT •
000042
WIDTH »
000120
XFTCOM*
000000
XFTOOSi
000000
XFTMUOp
000000
XFTRPGW
000000
$$PASS»
000000
. AB5,
000000
000572
000
001
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A002
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7-
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1*122«*
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3« 13*»
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3» 9#
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3- ll#
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2-l77#
b- 7
5-33
CROSS ReFfcRENCE TABtt M.J
AERROR
2* 9l«*
CALL
2« 73#
CALL5
£• 69#
CMKPNT
2* 96»
DIAL
2-324#
ERROR
2" 18«
FIRROR
2* 28#
FREM5B
2-2Sl#
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2«i24#
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2- 39#
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2« 24<>
MOOEND
2«2d2M
MOOSTA
2»179#
MQVMSB
2»273#
MOVSEG
2-297#
OUTMSB
2-2d9*
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2«222#
POP
2" 53#
PUSH
2- 57i»
QORVR
2-l46i»
RELBUF
2«l38#
RESREG
2-lia7#
RETEMT
2«2S0f*
RETURN
2» 77#
SAVREG
2»lid2#
SERROR
2* 3S#
SETABS
2«165#
STOEV
2-3'i3#
SWPCAL
2» 84#
WERROR
2«» 43*r
CROSS REfERENCe TaBLE C«l
9952(9
, ABS, 55520
5-34
