Concurrent error detection for restricted fault sets in sequential circuits and microprogrammed control units using convolutional codes

A methodology is developed using convolutional codes for online detection of sequencing errors in sequential circuits induced by any given set of transient faults. Key outputs are added to the machine. In the case of microprogrammed control units, key bits are appended to each microinstruction. The keys are chosen such that all sequences of key outputs are code sequences in a convolutional code. Using an error-detecting decoder for the code, all transient sequencing errors resulting from faults in the fault set can be detected with latency not exceeding the latency distance of the convolutional code.