Relay computers - OR functionality - symbology

From: Paul Koning <>
Date: Wed Sep 29 08:17:58 2004

>>>>> "Pete" == Pete Turnbull <> writes:

 Pete> As for confusing addition and the logical OR function with
 Pete> binary numbers, you don't normally perform logic on binary
 Pete> numbers, only on bits representing truth values. Describing
 Pete> "1011 OR 0101" as part of a logic equation is sloppy; it's
 Pete> actually four put together.

>From a math point of view, justifying the use of add and multiply
symbols, this is viewed as arithmetic modulo 2. You'll note that
addition mod 2 is exactly XOR (not inclusive OR) and multiplication is
exactly AND -- which is why that notation came across.

Looking at things this way is helpful if you want to understand CRC,
for example. Or so I've heard -- number theory is unfortunately
mostly over my head. Same goes for coding in general (ECC and such)
or various forms of encryption.

Received on Wed Sep 29 2004 - 08:17:58 BST

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