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
An arithmetic and logic unit with imperfect self-checking
capability is analyzed to determine the minimum required
rollback distance for the recovery procedure.