DSL/90: a digital simulation program for continuous system modeling

Abstract

Computer simulation has been used for some time in the analysis and design of dynamic systems. With recent advancements in computer performance, the field of dynamic simulation---long the exclusive domain of the analog computer---has begun to utilize digital methods. No less than a score of digital simulation programs have appeared since R. G. Selfridge's pioneering effort in 1955; and the number is ever-increasing. These programs offer a convenient method of simulating continuous system dynamics employing well-known and easy-to-use analog computer programming techniques. The common starting point for such simulation is the conventional analog block diagram, and the common approach is the breakdown of the mathematical system model into its component parts or functional blocks. These blocks, having a near one-to-one correspondence with analog computing elements such as integrators, summers, limiters, etc., usually appear as subroutines within the simulator program. Using one of the simulation packages, "programming" involves no more than merely interconnecting the functional blocks by a sequence of connection statements according to the rules laid down by the input language. This interconnecting of blocks is analogous to the wiring of the patchboard on an analog computer. Therefore, these digital-analog simulation programs combine the best features of the analog and digital computers: the flexibility of block connection structure of the former and the accuracy and reliability of the latter.