Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!seismo!husc6!bloom-beacon!think!ames!ptsfa!ihnp4!inuxc!iuvax!pur-ee!j.cc.purdue.edu!aa1 From: aa1@j.cc.purdue.edu (Saul Rosen) Newsgroups: comp.arch Subject: Re: An old fashioned memory technology, CRT's, how'd they work? Message-ID: <4770@j.cc.purdue.edu> Date: Thu, 16-Jul-87 13:15:43 EDT Article-I.D.: j.4770 Posted: Thu Jul 16 13:15:43 1987 Date-Received: Sat, 18-Jul-87 18:30:27 EDT References: <602@madvax.UUCP> Reply-To: aa1@j.cc.purdue.edu.UUCP (Saul Rosen) Organization: Purdue University Lines: 24 In article <602@madvax.UUCP> cw@madvax.UUCP (Carl Weidling) writes: > > Yesterday I bought a book called "Bit by Bit, An Illustrated History >of Computers", by Stan Augarten,Ticknor & Fields,NY,1984. > 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? Of course the statement you quote about Williams' tube memory sounds like nonsense. No positively charged electrons! The charged spot lasted about a fifth of a second. It had to be regenerated at least five times a second, and that provided a real memory. Williams' tube memory is described in all of the old books about computers. One of the more recent references is "A History of Computer Technology" by Michael R. Williams, Prentice-Hall, 1985.