PLATYPUS: A PLA Test Pattern Generation Tool

Abstract

PLATypus (PLA Test pattern generation and logic simulation tool) is an efficient tool for large PLAs which is interfaced with other existing PLA tools such as the constrained/unconstrained, simple/multiple folding program PLEASURE and the logic minimizer ESPRESSO II-C developed at the University of California at Berkeley. PLATYPUS uses biased random test generation as a quick preprocess followed by a deterministic test generation process to achieve the best balance between efficient run time and test set minimality. The algorithm adopted in the deterministic phase is exact, i.e., it achieves the highest possible test coverage by generating a test for every testable fault. Powerful heuristics are introduced in the area of fault processing order, backend fault simulation, “don't-care” bit fixing, and on-the-fly test compaction to achieve the best performance of PLATYPUS. The deterministic test generation algorithm is based on both complementation and tautology check of a logic cover. Both complementation and tautology check are performed by an advanced method used in the logic minimizer ESPRESSO-II. PLATYPUS supports both folded and unfolded PLAs, and both crosspoint and stuck-at fault models. PLATYPUS can also be used as a logic simulation tool and redundancy identifier. Test pattern generation has been performed by PLATYPUS on a large number of industrial PLAs.