Report Number: CS-TR-74-420
Institution: Stanford University, Department of Computer Science
Title: Partially self-checking ciruits and their use in performing
Author: Wakerly, John F.
Date: August 1973
Abstract: A new class of circuits called partially self-checking
circuits is described. These circuits have one mode of
operation called secure mode in which they have the
properties of totally self-checking circuits; that is, every
fault is tested during normal operation and no fault can
cause an undetected error. They also have an insecure mode of
operation with the property that any fault which affects a
result in insecure mode is tested by some input in secure
mode; however, undetected errors may occur in insecure mode.
One application of these circuits is in the arithmetic and
logic unit of a computer with data encoded in an
error-detecting code. While there is no code simpler than
duplication which detects single errors in logical operations
such as AND and OR, it is shown that there exist partially
self-checking networks to perform these operations. A
commercially available MSI chip, the 74181 4-bit ALU, can be
used in a partially self-checking network to perform
arithmetic and logical operations.