Quadded NOR Logic

Quadded Logic, a technique for the introduction of redundancy to digital systems, allows a number of component failures to occur in the system without disturbing its capacity to perform the function for which it was designed. This paper describes quadded logic using the NOR gate as the basic building block. A reliability prediction technique is shown with which the performance of this redundancy scheme can be evaluated. The gains in reliability possible through the use of quadding depend on the reliability of the nonredundant gates that make up the redundant stage. Where these gates are already very reliable, the probability of failure of the NOR function can be reduced by several orders of magnitude.