Strongly fault secure PLAs and totally self-checking checkers

A general approach is presented to the design of totally self-checking (TSC) programmable logic arrays (PLAs). A strongly fault secure (SFS) implementation is suggested for the functional PLA, which is shown to be SFS whenever the output is encoded by two-rail code. K-unit TSC checker (TSCC) element are defined to construct TSC checkers. The TSCC is very appropriate for the companion of the SLF PLA since a given input codeword set is sufficient for testing the TSCC. The minimum number of tests needed for a type-m two-rail code K -unit TSCC is 12^m. This is a generalization of the fact that four test patterns are sufficient for testing an XOB parity checker tree. As an application, a novel design of a TSC comparator with an arbitrary number of inputs is presented