
A Symbolic Analysis of Relay and Switching Circuits (1937) [pdf] - jcgr
https://www.cs.virginia.edu/~evans/greatworks/shannon38.pdf
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jesuslop
Very nice. The current rendering of this would be to formulate with
relay/resistors the 2 gate NOR as universal gate giving arbirary boolean
functions and the 2 NOR crossed feedback setup as RS-flip/flop or elementary
memory bit. All this can be done with hobyist materials.

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jhallenworld
Relay logic was certainly used prior to this. For example elevator call logic
goes back to the 20s:

[http://elevation.wikia.com/wiki/Elevator_control_system](http://elevation.wikia.com/wiki/Elevator_control_system)

Clearly the engineers involved had some way to think about it, but I suspect
were not scholarly enough to write a paper about it. (not that I've researched
this.. perhaps there were earlier papers).

Edit: Well here is a patent:
[https://patentimages.storage.googleapis.com/82/ae/57/d431cf0...](https://patentimages.storage.googleapis.com/82/ae/57/d431cf0f65e923/US1904647.pdf)

David Lindquist was Otis's lead engineer..

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kens
Interestingly, up until the early 1950s it was still controversial if Boolean
algebra was useful for computer design. The argument was that buildable
circuits were simple enough to analyze without Boolean algebra so it was
pointless mathematical formalism.

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olodus
Awesome. Was looking for this after reading that other awesome blog post about
Boole. Once again HN to the rescue, saving me from a Google search.

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hypeibole
Do you have a link to the post about Boole?

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tacon
This appears to be the referenced post:

[https://news.ycombinator.com/item?id=19091398](https://news.ycombinator.com/item?id=19091398)

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cabalamat
Is this where ladder logic comes from?

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qntty
I believe this paper is the first time that anyone thought to analyze
electronics using logic at all. Nobody thought that techniques used to analyze
philosophical and mathematical arguments could be used to understand
electronic signals before Shannon.

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codewritinfool
This is great

