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From: cw@madvax.UUCP (Carl Weidling)
Newsgroups: comp.arch
Subject: An old fashioned memory technology, CRT's, how'd they work?
Message-ID: <602@madvax.UUCP>
Date: Mon, 13-Jul-87 16:22:38 EDT
Article-I.D.: madvax.602
Posted: Mon Jul 13 16:22:38 1987
Date-Received: Wed, 15-Jul-87 01:25:37 EDT
Organization: Varian Instruments, Walnut Creek CA
Lines: 19


	Yesterday I bought a book called "Bit by Bit, An Illustrated History
of Computers", by Stan Augarten,Ticknor & Fields,NY,1984.
	It seems like a good book from what I've seen glancing through it,
but, I was reading about the design of the Mark I in Manchester,England
where it says: "He [F.C. Williams, the project's chief engineer] hit upon
the idea of employing ordinary cathode ray tubes [to solve the problem of
internal memory storage]...Their operating principle was quite simple;
"guns" in the bases of the tubes shot positively and negatively charged
electrons at the faces of the tubes, thus storing bits in the form of charge
spots, which, by the way, were quite visible to the eye."
	Well, I have a problem with "positively and negatively charged
electrons", but also, with how this can be memory.  How long did the charges
last?  were they refreshed? How was the memory read after being stored?
	If anybody out there knows this stuff, I would be appreciative
if you could enlighten me.  My limited impression is that the book is better
than this little excerpt would make it appear.
Regards,
Carl Weidling