A Symbolic Analysis of Relay and Switching Circuits (1937) [pdf](cs.virginia.edu)

45 pointsby jcgrvor 7 Jahren9 comments

cs.virginia.edu

A Symbolic Analysis of Relay and Switching Circuits (1937) [pdf]

https://www.cs.virginia.edu/~evans/greatworks/shannon38.pdf

10 comments

jesuslopvor 7 Jahren

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.

jhallenworldvor 7 Jahren

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

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...

David Lindquist was Otis's lead engineer..

kensvor 7 Jahren

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.

olodusvor 7 Jahren

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.

hypeibolevor 7 Jahren

Do you have a link to the post about Boole?

taconvor 7 Jahren

This appears to be the referenced post:

https://news.ycombinator.com/item?id=19091398

cabalamatvor 7 Jahren

Is this where ladder logic comes from?

qnttyvor 7 Jahren

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.

[deleted]vor 7 Jahren

codewritinfoolvor 7 Jahren

This is great