Report Number: CSL-TR-75-96
Institution: Stanford University, Computer Systems Laboratory
Title: A rollback interval for networks with an imperfect self-checking property
Author: Shedletsky, John J.
Date: December 1975
Abstract: Dynamic self-checking is a technique used in computers to detect a fault quickly before extensive data contamination caused by the fault can occur. When the self-checking properties of the computer circuits are not perfect, as in the case with self-testing only and partially self-checking circuits, the recovery procedure may be required to roll back program execution to a point prior to the first undetected data error caused by the detected fault. This paper presents a method by which the rollback distance required to achieve a given probability of successful data restoration may be calculated. To facilitate this method, operational interpretations are given to familiar network properties such as the self-testing, secureness, and self-checking properties. An arithmetic and logic unit with imperfect self-checking capability is analyzed to determine the minimum required rollback distance for the recovery procedure.