A fault model for PLAs

A fault model for programmable logic arrays (PLAs) is discussed that handles four classes of faults: multiple stuck-at faults, multiple bridging faults, multiple crosspoint faults, and faults due to breaks in lines. It is shown that a test that detects all multiple crosspoint faults also detects all multiple stuck-at faults, multiple bridging faults, and any combination of the above. It is also shown that multiple faults form a substantial part of the set of all faults in PLAs. Experiments with test generators show that tests detecting all single testable crosspoint faults also detect all testable stuck-at faults. The experiments also show that the test strategies based on the single-crosspoint fault model cover the greater part of all faults in PLAs