A tool for simulating real-time systems

The author describes a computer-aided software engineering tool that supports the simulation of real-time systems as modeled by dataflow diagrams (DFDs) augmented by control specifications in the form of state transition diagrams (STDs). The kind of simulation provided is token-based symbolic simulation. An interactive version of this tool animates DFDs and STDs, showing token counts on stores and data flows into primitive processes, and flow rates on data flows into nonprimitives. Two views of the simulation are supported. The essential view simulates the model in the absence of resource contention. The implementation view simulates the model with finite resources. The animation of the model can be used to find errors in the specification, and to try out different resource configurations when the simulation indicates the system might not meet performance requirements