TELECOM Digest OnLine - Sorted: Re: Computer "Logic" in 1922 Panel Switching

Re: Computer "Logic" in 1922 Panel Switching

Dennis Ritchie (
Fri, 18 Aug 2006 05:21:42 -0000

Jim Haynes <> wrote in message

> Also I believe it was exposure to telephone switching apparatus that
> led Claude Shannon to realize that Boolean algebra could be useful for
> describing and analyzing switching circuits.

Shannnon's start with this was his MS thesis in the 1930s, but of
course he could have been exposted to phone switching before he was at
Bell Labs.

> A book "The Design of Switching Circuits" by some Bell Labs guys
> Keister, Ritchie and Washburn is something of a cookbook of relay
> circuits for various purposes. Then at the end of the book they
> introduce some of Shannon's insights for circuit analysis and design.
> Shannon's work applied to combinatorial circuits; later it was Huffman
> who worked out the application to sequential circuits.

Actually, there's tons of stuff about sequential circuits in KR&W, of
which I have multiple copies, including Keister's personal copy signed
by the authors. I helped empty his house when he moved to Cape Cod
and he gave it to me -- and the Ritchie was my father.

The book was published in 1951, and the thing it doesn't have much
about is transistor (let alone integrated) circuits. About as much
space (a few pages) is on cold-cathode tubes.


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