Multibit correcting data interface for fault-tolerant systems

A fault-detecting, bidirectional data interface between uncoded data from one component, such as a processor, and coded data in the rest of the system is described. This interface is capable of correcting a single multibit symbol error or detecting the occurrence of two such errors. The device uses a shortened Reed-Solomon code, and two practical symbol sizes are considered; nibble (4-bit) errors are protected by a (40, 32) binary equivalent shortened code, and byte errors are covered by a (80, 64) binary-sized code. The Reed-Solomon codes have maximum protection levels, even when shortened, and allow simplifying the design options. A dual orthogonal basis used for the symbols´ representations provides significant hardware savings. The interface unit achieves internal fault detection by comparing regenerated parity values in a totally self-checking equality checker. A fault-tolerant ultrareliable memory module is proposed and evaluated. An illustrative design is realized using a single desktop programmable gate array