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Topic: Selectron tube

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	Selectron tube: Definition and Links by Encyclopedian.com
		By that time their primary customer, John von Neumann's IAS machine, was forced to switch to the Williams tube for storage, and RCA eventually had to scale down the Selectron from storing 4096 bits, to 256.
		The original 4096-bit Selectron was a large (5 inch by 3 inch) vacuum tube with a cathode running up the middle, surrounded by two separate sets of wires forming a cylindrical grid, a dielectric material outside of the grid, and finally a cylinder of metal conductor outside the dielectric, called the signal plate.
		The two sets of grid wires were normally "biased" slightly negative, so that the electrons from the cathode could not flow through the grid and reach the dielectric.
	www.encyclopedian.com /se/Selectron-tube.html (527 words)

	Selectron tube - Wikipedia, the free encyclopedia
		The Selectron was an early form of digital computer memory developed by Jan A. Rajchman and his group at the Radio Corporation of America under the direction of Vladimir Zworykin, of television technology fame.
		The glass envelope of the 256-bit tube was of approximately the same physical dimensions as the earlier cylindrical model.
		Both the Selectron and the Williams-Kilburn CRT memories were superseded in the market by the more compact and cost effective core memory, in the early 1950s.
	en.wikipedia.org /wiki/Selectron_tube (490 words)

	Selectron tube
		The Williams-Kilburn tubes (commonly known as Williams tubes) were used on several of the early stored program computers, including the Manchester 'Baby' (1948) and the Manchester Mark I which became operational in 1949, and the Institute of Advanced Study (IAS) machine spearheaded by von Neumann at Princeton, finally completed in 1951.
		The Selectron tube was an early form of computer memory developed by RCA (Radio Corporation of America).
		Each one cost about $500 to build, and while they were more reliable and faster than the Williams-Kilburn tube, their cost meant they were used only on a few machines.Both systems were replaced in the market with core memory, as soon as that became widely available.
	cs-exhibitions.uni-klu.ac.at /index.php?id=309 (385 words)

	Selectron tube
		The smaller capacity 256-bit "production" device was in a similar vacuum tube envelope, but built with a memory structure of discrete storage eyelets in a rectangular planar sandwich rather than a cylindrical continuous storage surface topology.
		The 256-bit Selectron was projected to cost about $500 to build in a production context, and while they were more reliable and faster than the Williams tube, that cost meant they were used only in one computer, the RAND Corporation's JOHNNIAC.
		Both the Selectron and the Williams-Kilburn CRT memories were superceded in the market by the more compact and cost effective core memory, in the early 1950s.
	www.mrsci.com /Computer-Memory/Selectron_tube.php (435 words)

	Encyclopedia of 20th Century Technology (Site not responding. Last check: 2007-11-02)
		The cathode ray tube was another wartime development and the persistence of the phosphor display screen once illuminated by the cathode ray provided the memory.
		The Williams-Kilburn tubes (commonly known as Williams tubes) were used on several of the early stored program computers, including the Manchester 'Baby' (1948) and the Manchester Mark 1 which became operational in 1949, and the Institute of Advanced Study (IAS) machine spearheaded by von Neumann at Princeton, finally completed in 1951.
		The Williams tube memory had a big advantage over delay line memory in that it allowed fast random access (any memory location could be addressed and read directly).
	www.routledge-ny.com /ref/20ctech/computer.html (1986 words)

	The RCA Selectron in 1946
		Structure A Selectron tube consists of a large cylindrical vacuum tube with a thermionic cathode down the axis and a dielectric forming the curved surface.
		The Selectron is designed to be able to control the potential at each such bit position, to the potential of either the cathode or the collector, independent of the state of any other bit position.
		In the event the tubes were still not available in the spring of 1948 (or even according to Max Newman by the late summer of 1948), and the IAS computer, for which it had been specifically intended, had to be switched to using a Williams-Kilburn CRT store.
	www.computer50.org /mark1/moore.school/selectron.html (1019 words)

	Williams Tube Random Access Memory Device in 1946
		This was invented by Fred Williams at England's Manchester University in 1946 and was later used in the Manchester Mark I computer.
		This was a modified CRT where the electron beam struck a mica wafer into which a grid of nickel-plated steel eyelets was embedded.
		The Selectron tube was a failure as manufacturing difficulties limited it to 256 bits of storage, compared to the 2048 bits for the Williams tube of that time.
	www.cedmagic.com /history/williams-tube.html (204 words)

	C:\BELLBO~1\COMPSR&E\HTMFILES\00000115.HTM
		This tube is also planned to have a non-amplitude-sensitive switching system whereby the electron beam can be directed to a given spot on the plate within a quite small fraction of a millisecond.
		Inasmuch as the storage tube is the key component of the machine envisaged in this report we are extremely fortunate in having secured the cooperation of the RCA group in this as well as in various other developments.
		We shall accordingly assume throughout the balance of this report that the Selectron is the modus for storage of words at electronic speeds.
	research.microsoft.com /~gbell/Computer_Structures__Readings_and_Examples/00000115.htm (936 words)

	Active shadow mask color CRT - Patent 4881016
		In a color cathode ray tube, a single selectron beam is deflected through a deflection yoke and passes through a collimation lens to an active shadow mask formed with a plurality of apertures to divide the beam into a plurality of segments.
		The improvement as defined in claim 11 wherein the beam focusing means includes a plurality of lens electrodes respectively mounted in operative relation to the apertures and control voltage means connected to the lens electrodes for regulating corrective restoration of the travel of the electrons in the beam segments along the parallel paths.
		For example, the exact electrode voltages and spacings that are most conveniently employed in a particular tube made in accordance with this invention, depend on the requirements that are to be met by such tube.
	www.freepatentsonline.com /4881016.html (2888 words)

	Glass Analogue to Digital converter
		This is an extract from an article on pulse code modulation, from Electronic Engineering magazine, April 1953, describing a very ingenuious use of a cathode-ray tube to perform 7-bit analogue to digital conversion, outputting a serial binary data stream from an analogue input.
		The electron beam produced by a normal gun is deflected into one of thirty-six sectors on the "screen" of the tube, each sector being electrically isolated from the rest.
		Output leads from the sectors are taken to four E9 nine-pin bases mounted on the tube face, which is also made fluorescent in the normal way, so that the position of the beam can be seen.
	www.electricstuff.co.uk /glassadc.html (692 words)

	The First Generation, 1950 - 1960
		Computers of the first generation stored their programs internally and used the vacuum tubes as their switching technology, but beyond that had little else in common.
		Its central processor contained over 5,000 tubes, installed in cabinets that were arranged in a 10-foot X 14-foot rectangle.
		Transistors, replacing vacuum tubes on a one-to-one basis, solved the problems of a tube's reliability, heat, and power consumption.
	homepages.transy.edu /~jmiller/web706/pf33.htm (2592 words)

	Tales From The Tone Lounge; Vintage Tube Boxes
		The tubes in my collection state in green silkscreening they are manufactured in the U.S. of A. They are also usually TV tubes, and this example is a 6LE8.
		A 6GH8 is a 9-pin triode-pentode tube and fun to use with the pentode as a voltage amplifier coupled to the triode as a split-load phase inverter.
		One electronics manufacturer told me if they bought tubes in a minimum lot of 10,000 (not hard to use them up either if you are a serious manufacturer) they got their name and/or logo silkscreened on the tubes for free.
	www.tone-lizard.com /Vintage_Tube_Boxes.htm (9871 words)

	C:\BELLBO~1\COMPSR&E\HTMFILES\00000116.HTM
		This can, of course, be achieved by a Selectron-like tube which causes its screen to fluoresce when data are put on it by an electron beam.
		For definiteness in the subsequent discussions we assume that associated with the output of each Selectron is a flip-flop.
		Our fundamental unit of memory is naturally adapted to the binary system since we do not attempt to measure gradations of charge at a particular point in the Selectron but are content to distinguish two states.
	research.microsoft.com /users/GBell/Computer_Structures__Readings_and_Examples/00000116.htm (824 words)

	Preliminary discussion of the logical design of an electronic computing instrument
		One is to have a gate tube associated with each flip-flop of AR in such a fashion that this gate is open if a digit is 1 and closed if it is null.
		The details of the process of obtaining a pair of orders from the Selectron are thus as follows: The contents of CC are copied into FR, the proper Selectron location is selected, and the contents of the Selectrons are transferred to SR.
		Transferring the number to the Selectron via the accumulator is also desirable if the dual machine method of checking is employed, for it means that even if numbers are only checked in their transit through the accumulator, nevertheless every number going into the Selectron is checked before being placed there.
	www.cs.unc.edu /~adyilie/comp265/vonNeumann.html (19909 words)

	6L6 Tubes in Stock
		These tubes originally were found in large console radio sets, in their first pre-WWII form of the 6L6G, and the 6L6 metal type.
		This was also the tube of choice for many tube tester manufacturers to use as their calibration standard.
		The tube is a short flat topped tube with a brown base, and a large grey plate structure inside.
	www.audiotubes.com /6l6.htm (3892 words)

	Tube clamps (Site not responding. Last check: 2007-11-02)
		There are the tube clamps in several processing steps assembled.
		In the controls are 9 linear positioning units integrated.
		Selectron MAS, 3 CPU's 752; more than 300 I/O; in group with 9 stepping motors
	www.asomatic.ch /tube_clamps.htm (78 words)

	Untitled Document (Site not responding. Last check: 2007-11-02)
		JOHNNIAC went operational for the first time in the first half of 1953 (no one seems to know the exact date of this event) with 256 40-bit words of RCA Selectron Tube storage, a 40-column numeric printer, a converted IBM Collator for a card reader and a converted IBM Summary Punch.
		It had two 19-bit instructions per word with two sets of "transfer" instructions (what are now called jumps or branches), one set to the left half word and one set to the right half word.
		The Selectron Tubes were removed in 1954 in anticipation of the installation of the core storage.
	www.cs.umass.edu /~weems/CmpSci535/JOHNNIAC.html (444 words)

	Visible Storage
		The fact that the CRT produces a spot of light in the process is coincidental and could not be seen because the tube was covered with a metal plate used to detect the charges.
		RCA Selectron tube, which used a hard-to-manufacture mesh of small charged iron rings.
		All of these approaches, including the Williams Tube, were made obsolete by the invention of magnetic core memory.
	www.computerhistory.org /VirtualVisibleStorage/artifact_main.php?tax_id=02.03.02.00 (228 words)

	[No title]
		With over 165,000 tubes in stock, this database is quite large.
		If you are a collector, or if the box condition is as important to you as the tube, state so in your order and we will hand pick a suitably boxed tube for you.
		On the other hand, if you don't see the exact tube type you want, email the inquiry form and we will let you know what equivalents are available.
	www.vintagelectron.com /id4_m.htm (419 words)

	The history of (computer) storage
		After the 17th century inventions that usually need some kind of aid to read the information from a particular storage were made.
		Examples of that are the punch card, punched tape, Phonograph, magnetic tape, magnetic drum, Telegraphon and the selectron tube.
		In 1956 IBM invented the hard disk with a size of 5 MB, what was really fantastic for this time.
	cs-exhibitions.uni-klu.ac.at /index.php?id=187 (596 words)

	LAB.ARTEMATRIX.ORG
		The glass, usually in the form of a tube, is held by two rotating chucks.
		We will focus on the use of tubes for audio and will look mainly at triodes, with a look later at multi-grid tubes for audio.
		Virtually all receiving tubes not listed here are out of production; and will likely stay that way.
	lab.artematrix.org /links.php?c=SPEC (556 words)

	Williams Tube memory, Selectron question, and Charactron
		> >One might argue that a neon bulb or a decatron isn't properly a "tube" >(they certainly aren't "valves" because they don't have a control grid >like a triode), but they are non-linear devices that are capable of >storing (and displaying) state information and performing simple logic >functions.
		It was based on work he began in 1904 investigating the "Edison Effect", of which he and Edison had discovered earlier in 1889 in USA, in order to make a rectifying valve.
		On the other hand, Lee deForest patented the Audion which is a three element valve, or "tube" in USA terms, in 1906.
	www.classiccmp.org /pipermail/cctalk/1999-August/131664.html (412 words)

	Early Devices display
		These three were used to transmit a pulse down the line in a positive fashion, and these three are used to transmit a pulse down possibly another line, usually a different line, in a negative fashion.
		Storage is achieved by painting 16x16 spots on the screen of the tube.
		SWAC had 40 of these tubes, for a total memory capacity of 256 words of 40 bits each.
	infolab.stanford.edu /pub/voy/museum/pictures/display/2-1.htm (793 words)

	History of Data Storage (Site not responding. Last check: 2007-11-02)
		In 1946 RCA started the development of the Selectron tube.
		It was an early form of computer memory and the largest selectron tube measured 10 inches and could store 4096 bits.
		As these tubes were very expensive, they were very short-lived on the market.
	www.stud.u-szeged.hu /Vekony.Miklos (988 words)

	Modern Mechanix » We CAN Control the Weather! (Site not responding. Last check: 2007-11-02)
		It will contain several thousand tubes (one famous computer had over 20,000), 40 being Selectron tubes, newly developed by Dr. Jan Rajchman, one of Dr. Zworykin’s associates.
		Each of these tubes has the amazing ability to handle or store in its “memory” 4,096 different signals or bits of information.
		Each Selectron tube contains two sets of fine wires, set at right angles to each other, between the source of electrons and an insulator on whose surface electrostatic charges called “writing” can be stored.
	blog.modernmechanix.com /2006/07/14/we-can-control-the-weather (1427 words)

	[No title]
		The Selectron tube, under development by the Radio Corporation of America from about 1945, was for a time thought to be the most promising digital storage device.
		The success of Williams tubes was based upon the discovery of a relatively simple method for effecting this regeneration.
		Williams tubes could, moreover, be built comparatively cheaply from standard components and the ideas were soon taken up by other computer groups in the USA and elsewhere.
	ed-thelen.org /comp-hist/EarlyBritish-05-12.html (9803 words)

	Johnniac
		Jim Humberd says here that there was a meeting at the Johnniac Computer where the meeting notice said that this was the first public demonstration of a typewriter communicating with a computer.
		Each of the 80 glistening Selectron vacuum tubes held 256 bits of data and cost RCA $500 to manufacture.
		(Hence, Selectron memory was quickly replaced by core memory, a matrix of tiny iron-oxide rings representing 1s or 0s, depending on the direction of magnetization.)
	ed-thelen.org /comp-hist/johnniac.html (1604 words)

	Oral History RCA Endres Page3 Point Contact Solectron
		In the late 1940s, the principal random access memory device was the Williams tube in which 256 bits were stored as charges on the phosphor of 5” cathode ray tubes.
		This is a Solectron tube, as used by Dick Endres in his work at RCA to design a 5120 bit memory system for the Air Force in 1951.
		This is an SB256 tube, (256 bits) and, according to Dick, may represent the pinnacle of the vacuum tube art.
	www.semiconductormuseum.com /Transistors/RCA/OralHistories/Endres/Endres_Page3.htm (295 words)

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