Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!seismo!husc6!sri-unix!sri-spam!ames!ucbcad!zen!ucbvax!jade!saturn!ucscc.UCSC.EDU!haynes From: haynes@ucscc.UCSC.EDU.ucsc.edu (99700000) Newsgroups: comp.arch Subject: Re: An old fashioned memory technology, CRT's, how'd they work? Message-ID: <547@saturn.ucsc.edu> Date: Wed, 15-Jul-87 21:08:23 EDT Article-I.D.: saturn.547 Posted: Wed Jul 15 21:08:23 1987 Date-Received: Tue, 21-Jul-87 04:11:16 EDT References: <602@madvax.UUCP> <786@cpocd2.UUCP> Sender: usenet@saturn.ucsc.edu Reply-To: haynes@ucscc.UCSC.EDU (Jim Haynes) Organization: California State Home for the Weird Lines: 30 Actually the original Williams tube used, I believe, perfectly ordinary CR tubes, no flood gun inside and no special electrode inside. Harry Huskey here worked on these things, but he isn't handy for me to ask just now. Refreshing can be done with the same beam that does the writing because the beam is randomly addressable, not scanning. So you only need to store the one bit per tube that you are currently reading. In fact random access was the whole point, to avoid the time delays inherent in delay-line storage. IBM built its first marketed computers, 701 and 702, with this technology; then quickly switched to cores and brought out the 704 and 705 with the rest of the hardware mostly the same, but with somewhat different architecture. (701 was fixed-point only, 704 added floating point; 701 stored instructions in half words, 704 used full word instructions, added index registers). Williams tubes were also used in SWAC, which is the machine Harry Huskey built for the Bureau of Standards branch on the UCLA campus. They were also used in several other of the early computers built by universities. There's an old book "High Speed Computing Devices" by Electronic Research Associates (a forerunner of Remington Rand Univac) that may be in some libraries. Seems like the flood guns and extra electrodes came later when people realized that it would be possible to make oscilloscope CRTs with arbitrarily-long persistence that way. Hughes Aircraft used to make CRTs and oscilloscopes with these technologies. haynes@ucscc.ucsc.edu haynes@ucscc.bitnet ..ucbvax!ucscc!haynes