Random-access memory: Difference between revisions

Revision as of 21:10, 23 August 2024

Revision as of 20:23, 25 August 2024

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[[File:Early SSA accounting operations.jpg|thumb|These IBM [[tabulating machine]]s from the mid-1930s used [[mechanical counter]]s to store information.]]

Early computers used [[relay]]s, [[mechanical counter]]s<ref>{{cite web|url=http://www-03.ibm.com/ibm/history/reference/faq_0000000011.html|title=IBM Archives -- FAQ's for Products and Services|work=ibm.com|url-status=livedead|archive-url=https://web.archive.org/web/20121023184527/http://www-03.ibm.com/ibm/history/reference/faq_0000000011.html|archive-date=2012-10-23}}</ref> or [[Delay-line memory|delay lines]] for main memory functions. Ultrasonic delay lines were [[bit-serial architecture|serial devices]] which could only reproduce data in the order it was written. [[Drum memory]] could be expanded at relatively low cost but efficient retrieval of memory items requires knowledge of the physical layout of the drum to optimize speed. Latches built out of [[triode vacuum tube]]s, and later, out of [[discrete transistor]]s, were used for smaller and faster memories such as [[Hardware register|registers]]. Such registers were relatively large and too costly to use for large amounts of data; generally only a few dozen or few hundred bits of such memory could be provided.

The first practical form of random-access memory was the [[Williams tube]]. It stored data as electrically charged spots on the face of a [[cathode-ray tube]]. Since the electron beam of the CRT could read and write the spots on the tube in any order, memory was random access. The capacity of the Williams tube was a few hundred to around a thousand bits, but it was much smaller, faster, and more power-efficient than using individual vacuum tube latches. Developed at the [[Victoria University of Manchester|University of Manchester]] in England, the Williams tube provided the medium on which the first electronically stored program was implemented in the [[Manchester Baby]] computer, which first successfully ran a program on 21 June, 1948.<ref>{{Citation | last = Napper | first = Brian | title = Computer 50: The University of Manchester Celebrates the Birth of the Modern Computer | url = http://www.computer50.org/ | access-date = 26 May 2012 | url-status = dead | archive-url = https://web.archive.org/web/20120504133240/http://www.computer50.org/ | archive-date = 4 May 2012 }}</ref> In fact, rather than the Williams tube memory being designed for the Baby, the Baby was a [[testbed]] to demonstrate the reliability of the memory.<ref>{{Citation |last1=Williams |first1=F. C. |last2=Kilburn |first2=T. |title=Electronic Digital Computers |journal=Nature |volume=162 |pages=487 |date=Sep 1948 |doi=10.1038/162487a0 |issue=4117 |postscript=. |bibcode=1948Natur.162..487W |s2cid=4110351|doi-access=free }} Reprinted in ''The Origins of Digital Computers''.</ref><ref>{{Citation |last1=Williams |first1=F. C. |last2=Kilburn |first2=T. |last3=Tootill |first3=G. C. |title=Universal High-Speed Digital Computers: A Small-Scale Experimental Machine |url=http://www.computer50.org/kgill/mark1/ssem.html |journal=Proc. IEE |date=Feb 1951 |volume=98 |issue=61 |pages=13–28 |postscript=. |doi=10.1049/pi-2.1951.0004 |url-status=dead |archive-url=https://web.archive.org/web/20131117101730/http://www.computer50.org/kgill/mark1/ssem.html |archive-date=2013-11-17}}</ref><!--[[User:Kvng/RTH]]-->