ROM-based finite state machines with PLA address modifiers

An effective method for the synthesis of address modifiers in sequential circuits is described. The method, based on serial decomposition, substantially reduces the address modifier circuit complexity for a given microprogram memory size. It can be used effectively for PMS based designs and for full custom designs. The method was implemented in C++ on a PC. It was tested on standard finite state machine (FSM) benchmarks. Results indicate that for a wide range of cases the method gives a substantial (more than 50%) reduction of required ROM capacity, which may result in a saving of the silicon area in the actual full custom implementation.