The semantics and execution of a synchronous block-diagram language

We present a new block diagram language for describing synchronous software. It coordi-nates the execution of synchronous, concurrent software modules, allowing real-time sys-tems to be assembled from precompiled blocks specified in other languages. The semanticswe present, based on fixed points, is deterministic even in the presence of instantaneousfeedback. The execution policy develops a static schedule—a fixed order in which to exe-cute the blocks that makes the system execution predictable.We present exact and heuristic algorithms for finding schedules that minimize systemexecution time, and show that good schedules can be found quickly. The scheduling algo-rithms are applicable to other problems where large systems of equations need to be solved.