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.