Relay computers - OR functionality - symbology

From: Pete Turnbull <>
Date: Tue Sep 28 18:58:52 2004

On Sep 28 2004, 15:52, Steve Thatcher wrote:
> from a self documenting sense, it makes no sense...
> when someone can pick up a logic description and understand it
WITHOUT having to figure out what each sytmbol means in the context of
the usage, then it is simply more understandable. If I picked up
something that had two binary numbers wiht a PLUS sign inbetween, I
would not assume that it meant OR, only if you would dig further does
the PLUS sign make sense. If you simply said OR, then there is no
confusion and it is self documenting. I think Sellam was trying to make
this point with regards to symbology.
> I agree with Sellam about the insanity part... The symbols are
> arbitrary and WORK as long as you have your language description at
> hand.

I don't -- agreed the symbols are to *some* extent arbitrary, but I
agree with Dwight. If they're arbitrary, then +/. are just as good as
|/&. The symbols Dwight used are part of *the* standard for logic
expression in Boolean mathematics, and make good sense if you think
about it (or know a little about it). The overloading of multiple
context-sensitive meanings for things is common in mathematics,
programming, and lots of other places. You just have to learn to live
with it. If you learn a new discipline or language, you have to learn
the semantics (just as a physicist knows that stress and strain are two
different things while the man in the street, having read his OED,
"knows" they're the same). Do you expect to pick up a book on some
strange programming language or some new science and understand the
syntax without some explanation?

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

And lastly, AND and OR are just two binary logic functions. There are
fourteen more, if remember my first year maths, all with ASCII symbols,
all of which predate C.

I sympathise with those who've not seen it before. It can be hard to
understand at first; logic is not common sense. It is, however,
logical :-)

Pete						Peter Turnbull
						Network Manager
						University of York
Received on Tue Sep 28 2004 - 18:58:52 BST

This archive was generated by hypermail 2.3.0 : Fri Oct 10 2014 - 23:37:32 BST