Machine Aid for Switching Circuit DesignDecimal classification: 621.375.2R257. Original manuscript received by the Institute, May 28, 1953; revised manuscript received June 29, 1953.

The design of circuits composed of logical elements may be facilitated by auxiliary machines. This paper describes one such machine, made of relays, selector switches, gas diodes, and germanium diodes. This machine (called the relay circuit analyzer) has as inputs both a relay contact circuit and the specifications the circuit is expected to satisfy. The analyzer (1) verifies whether the circuit satisfies the specifications, (2) makes systematic attempts to simplify the circuit by removing redundant contacts, and also (3) obtains mathematically rigorous lower bounds for the numbers and types of contacts needed to satisfy the specifications. A special feature of the analyzer is its ability to take advantage of circuit specifications which are incompletely stated. The auxiliary machine method of doing these and similar operations is compared with the method of coding them on a general-purpose digital computer.