Parity sensitive comparators

Abstract

Parity sensitive comparators are a new type of comparators designed to take advantage of the parity information present in most buses. Instead of simply comparing the signals carried by the buses, parity information is used to select the probably correct output in case of mismatch, thus avoiding an important percentage of errors to stop system functioning. These devices verify parity for each pair of compared groups and discard erroneous data when comparing, propagating the probably correct data and signaling the fact with a "recoverable error" output signal. Benefits of parity sensitive comparators are analyzed by means of a deep probabilistic study of the "parity bit per data byte" case that shows how they are able to recover more than the 97% of errors signaled by classical comparators. The output information of the comparators is also described, as well as its uses according to the level of reliability required.