A probabilistic measurement for totally self-checking circuits

The authors propose a probabilistic measurement for totally self-checking (TSC) circuits. This measurement is analogous to reliability of fault-tolerant systems and is defined as the probability of achieving TSC goal (PATG). PATG surpasses the TSC definitions in determining the applicability of a circuit in a given application environment. For example, it is shown that an embedded TSC two-rail checker with two out of its four code word inputs unavailable gains a higher PATG than that in the ideal case. It is also demonstrated that the extension of PATG concept to strongly fault-secure (SFS) circuits and strongly code disjoint (SCD) checkers. The PATG can be used in product specification, analogous to reliability, and can give precise behavioral description on fault/error handling performance of TSC circuits. This is a crucial step toward the practical applications of TSC or CED circuits.