The report describes a computer simulation of the Air Traffic Control Radar Beacon System (ATCRBS). Operating on real air traffic data and actual characteristics of the relevant ground interrogators, the FORTRAN program re- enacts system operation in a pulse-by-pulse manner. The level of detail thus incoprorated into the program structure enables a computer-generated representation of the air traffic controller's display to be produced. The versatility of the simulation model is further evidenced by the incorporation of program modifications which also make possible investigation of the Discrete Address Beacon System (DABS). These program modifications permit examination and evaluation of the effectiveness of DABS interrogations in an ATCRBS environment. Results of simulation of DABS operation in a 1980 interrogator environment are furnished in this document.