A General Purpose Digital Simulator and Examples of Its Application Part I: Description of the Simulator

GPSS 11, a general purpose digital systems simulation program based on a block diagram language. The program i s a result of incorporating improvements dictated by extensive experience in the application of a n earlier version. However, this article i s self-contained. Development and application of the language are illustrated by means of an example. Recent years have seen the development of several general purpose digital computer programs aimed at simplifying the task of carrying out simulation studies.' Among these is a program called the General Purpose Systems Simulator (GPSS). " ~ Substantial experience accumulated in the use of this program has led to a number of suggested improvements and the present article describes a second version of the program, called the General Purpose Systems Simulator 11 (GPSS II).~,~ GPSS 11 is consistent with the original GPSS program in the sense that it employs the same principles and that all functions performed by the earlier program can also be performed by GPSS 11. Although this paper does not assume prior knowledge of GPSS, before describing the new program some insight may be gained by giving a summary of the major improvements incorporated. In brief, these improvements are: Greater ability to sense the current state of the system, and to implement decisions based upon that state. " Variable statements " permit FORTRAN-like algebraic computations upon system variables. These capabilities provide much improved control over the flow of transactions in response to the current state of the system. The ability to associate a greater amount of information with each transaction in the form of eight parameters.