Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!seismo!mcvax!ukc!its63b!bct From: bct@its63b.ed.ac.uk (B Tompsett) Newsgroups: comp.arch Subject: Re: An old fashioned memory technology, CRT's, how'd they work? Message-ID: <523@its63b.ed.ac.uk> Date: Wed, 15-Jul-87 08:27:06 EDT Article-I.D.: its63b.523 Posted: Wed Jul 15 08:27:06 1987 Date-Received: Sat, 18-Jul-87 07:26:42 EDT References: <602@madvax.UUCP> Reply-To: bct@ecsvax.ed.ac.uk (B Tompsett) Organization: Dept. of Computer Science, Edinburgh University, U.K. Lines: 48 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]..." > If anybody out there knows this stuff, I would be appreciative >if you could enlighten me. From: Nigel TophamIt was in December 1946 that Williams and Kilburn started work on the CRT store, using commercially available CV1131 12-inch dia. CRTs [1]. The principle of a two-state electrostatic store can be visualised from the following simple experiment. Start with a focussed CRT beam and turn the beam current on (thus producing a charged dot) and off again repeatedly. Negative voltage pulses will be induced by capacitive coupling in a pick-up plate placed close to the outer surface of the CRT screen. Now move the beam whilst it is on so as to write a dash on the screen, then move the beam back whilst the current is off, and then switch the then switch on the current again. This time a positive pulse is induced. With dots and dashes representing logcal O and 1, readable as negative and positive pulses, a binary storage system is available. Although the electrostatic charge leaks away in about 0.2 seconds this can be refreshed in the same way that a modern MOS memory is refreshed. By the Autumn of 1947 the Manchester group had successfully stored 2048 bits of information for a period of several hours, and the way was clear to construct a prototype computer - in Williams words "...to subject the system to the most searching tests possible...". (Editited excerpt from S.H.. Lavington, A History of Manchester Computers, NCC Publications, Manchester, England, 1975, pp. 7-10.) [1] Williams, F.C., and Kilburn, T., "A Storage System for use with Binary Digital Computers", Proc IEE, vol. 96, pt. 2, no 30, 1949, pp. 183ff. -- -- > Brian Tompsett. Department of Computer Science, University of Edinburgh, > JCMB, The King's Buildings, Mayfield Road, EDINBURGH, EH9 3JZ, Scotland, U.K. > Telephone: +44 31 667 1081 x3332. > JANET: bct@uk.ac.ed.ecsvax ARPA: bct%ecsvax.ed.ac.uk@cs.ucl.ac.uk > USENET: bct@ecsvax.ed.ac.uk UUCP: ...!seismo!mcvax!ukc!ecsvax.ed.ac.uk!bct > BITNET: psuvax1!ecsvax.ed.ac.uk!bct or bct%ecsvax.ed.ac.uk@earn.rl.ac.uk