Interactive digital simulation

Abstract

Simulation of digital networks can be enhanced by interactive graphics to provide an experimental environment that rivals breadboarding as a "hands-on" logic-design experience.The simulator described here allows interactive keyboard entries during the simulation interval providing activation of network switches and pulsers, restarting or slowing the simulation, graphical expansion of modules in terms of their internal components, graphical pan and zoom for better resolution of sub-networks, and multiple viewing windows onto the virtual space of the network. The simulation is three-level and event driven, and allows the specification of periodic clock signals of unlimited duration.A pre-processor allows the macro definition of modules and provides the necessary independence of local variables that is required for multiple instantiation. Although inherently recursive, the macro processor can be supplemented with library macros that support iterative specification. This feature allows the construction of networks with interated cell structures.