Shannon, C. E. [Claude Elwood]; Moore, E. F. [Edward]

Machine aid for switching circuit design [Bell Monograph]

New York, N.Y. Bell Telephone Laboratories, Incorporated March 1954. First Separate Edition. 4 pages. 10 7/8 x 8 3/8 inches (275 x 213 mm) Publisher's printed grey, blue and black wrappers, stapled. Five holes punched at the spine as issued. Near Fine. Wraps. [28612]


The Proceedings of the I. R. E., Vol 41, October 1953 (pp.1348-1351 of the famous Computer Issue) first published this paper. Here offered in the Bell Telephone Systems Monograph Series (#2153: March 1954). We are not aware of any separate IRE offprint for this paper. Unless one is discovered this format constitutes the first separate edition.

A significant part of the design engineer’s job is how to efficiently and cost-effectively build a project. This paper describes a purpose-built machine (the relay circuit analyzer) that can remove unnecessary components while testing a circuit against its design requirements. The circuit analyzer design, while extensible, has a straightforward design and is explained using the simplest case.

"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 that 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." (from the Summary)

"Whether or not this particular kind of machine ever proves to be useful in the design of practical relay circuits, the possibility of making machines which can assist in logical design procedure promises to be of value to everyone associated with the design of switching circuits. Just as the slide rule and present-day types of digital computers can help perform part of the routine work associated with the design of linear electrical networks, machines such as this may someday lighten much of the routine work associated with the design of logical circuits." (from the Conclusion)

It was a brilliant idea and prescient. Today software replaces the mechanical implementation, but the idea is fundamentally the same. Computer-aided design in manufacturing plays a significant role in constructing and testing complex circuits like computer processors, which would be very difficult to test otherwise.

PROVENANCE: The personal files of Claude E. Shannon (unmarked). There were many examples of this item in Shannon's files.

REFERENCES:
Sloane and Wyner, "Claude Elwood Shannon Collected Papers," #80
Hook and Norman, "Origins of Cyberspace," #886

COLLECTORS NOTE: The Bell Telephone System Monograph series offered a way to obtain individual articles by Bell scientists regardless of where their work was first published. Many Monographs significantly postdate the original article publication. Because of this, they rarely constitute the coveted (and traditional) article offprint. If the journal of record issued no offprint, the Monograph might be the first separate publication - the closest the collector can come to a traditional offprint. We have done our best to place each Monograph properly in the article’s publishing history and welcome any corrections or additional information, especially regarding issues unknown to us.

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