Reliability of an Air Defense Computing System: Circuit Design

Extreme reliability resulting in no unscheduled down-time and a low ratio of scheduled maintenance to operate time was the objective of the AN/FSQ-7 design program. The circuit design philosophy of this program is presented. In addition, an approach is given whereby the concept of marginal checking is applied to determine quantitatively 1) the relative reliability of computer circuits and 2) that a margin of safety consistent with the circuit design philosophy existed. An Appendix is included setting forth actual examples in a qualitative manner.