Report Number: CSL-TR-76-115
Institution: Stanford University, Computer Systems Laboratory
Title: Principles of self-checking processor design and an example
Author: Wakerly, John F.
Date: December 1975
Abstract: A self-checking processor has redundant hardware to insure
that no likely failure can cause undetected errors and all
likely failures are detected in normal operation. We show how
error-detecting codes and self-checking circuits can be used
to achieve these properties in a microprogrammed processor.
The choice of error-detecting codes and the placement of
checkers to monitor coded data paths are discussed. The use
of codes to detect errors in arithmetic and logic operations
and microprogram control units is described. An example
processor design is given and some observations on the
diagnosis and repair of such a processor are made. From the
example design it appears that somewhat less than 50% overall
redundancy is required to guarantee the detection of all
failures that affect a single medium- or large-scale
integration circuit package.