Editing History of computing hardware (section)

===Manchester Baby===
{{Main|Manchester Baby}}
[[File:SSEM Manchester museum close up.jpg|thumb|left|alt=Three tall racks containing electronic circuit boards|A section of the rebuilt [[Manchester Baby]], the first electronic stored-program computer]]
The [[Manchester Baby]] (Small Scale Experimental Machine, SSEM) was the world's first electronic [[stored-program computer]]. It was built at the [[Victoria University of Manchester]] by [[Frederic Calland Williams|Frederic C. Williams]], [[Tom Kilburn]] and Geoff Tootill, and ran its first program on 21&nbsp;June 1948.<ref>{{citation |last=Enticknap |first=Nicholas |title=Computing's Golden Jubilee |journal=Resurrection |issue=20 |publisher=The Computer Conservation Society |date=Summer 1998 |url=https://www.cs.man.ac.uk/CCS/res/res20.htm#d |issn=0958-7403 |access-date=19 April 2008 |url-status=dead |archive-url=https://web.archive.org/web/20120109142655/http://www.cs.man.ac.uk/CCS/res/res20.htm#d |archive-date=9 January 2012}}</ref>

The machine was not intended to be a practical computer but was instead designed as a [[testbed]] for the [[Williams tube]], the first [[random-access memory|random-access]] digital storage device.<ref>{{citation |title=Early computers at Manchester University |journal=Resurrection |volume=1 |issue=4 |publisher=The Computer Conservation Society |date=Summer 1992 |url=https://www.cs.man.ac.uk/CCS/res/res04.htm#g |issn=0958-7403 |access-date=7 July 2010 |archive-url=https://web.archive.org/web/20170828010743/http://www.cs.man.ac.uk/CCS/res/res04.htm#g |archive-date=28 August 2017 |url-status=dead}}</ref> Invented by [[Frederic Calland Williams|Freddie Williams]] and [[Tom Kilburn]]<ref>{{cite web |website=Computer 50 |url=https://www.computer50.org/mark1/notes.html |archive-url=https://web.archive.org/web/20130606122154/http://www.computer50.org/mark1/notes.html |archive-date=2013-06-06 |title=Why Williams-Kilburn Tube is a Better Name for the Williams Tube}}</ref><ref>{{Citation |last=Kilburn |first=Tom |author-link=Tom Kilburn |title=From Cathode Ray Tube to Ferranti Mark I |journal=Resurrection |publisher=The Computer Conservation Society |volume=1 |issue=2 |year=1990 |url=https://www.cs.man.ac.uk/CCS/res/res02.htm#e |issn=0958-7403 |access-date=15 March 2012 |archive-date=2020-06-27 |archive-url=https://web.archive.org/web/20200627165410/http://www.cs.man.ac.uk/CCS/res/res02.htm#e |url-status=live }}</ref> at the University of Manchester in 1946 and 1947, it was a [[cathode-ray tube]] that used an effect called [[secondary emission]] to temporarily store electronic [[binary data]], and was used successfully in several early computers.

Described as small and primitive in a 1998 retrospective, the Baby was the first working machine to contain all of the elements essential to a modern electronic computer.<ref name=EarlyComputers /> As soon as it had demonstrated the feasibility of its design, a project was initiated at the university to develop the design into a more usable computer, the [[Manchester Mark 1]]. The Mark 1 in turn quickly became the prototype for the [[Ferranti Mark 1]], the world's first commercially available general-purpose computer.<ref name=NapperMK1>{{citation |last=Napper |first=R. B. E. |title=Introduction to the Mark 1 |website=Computer 50 |url=https://www.computer50.org/mark1/mark1intro.html |publisher=The University of Manchester |access-date=4 November 2008 |url-status=dead |archive-url=https://web.archive.org/web/20081026080604/http://www.computer50.org/mark1/mark1intro.html |archive-date=26 October 2008 }}</ref>

The Baby had a [[32-bit computing|32-bit]] [[word (data type)|word]] length and a [[computer memory|memory]] of 32&nbsp;words. As it was designed to be the simplest possible stored-program computer, the only arithmetic operations implemented in [[Computer hardware|hardware]] were [[subtraction]] and [[negation]]; other arithmetic operations were implemented in software. The first of three programs written for the machine found the highest [[proper divisor]] of 2<sup>18</sup> (262,144), a calculation that was known would take a long time to run—and so prove the computer's reliability—by testing every integer from 2<sup>18</sup>&nbsp;−&nbsp;1 downwards, as division was implemented by repeated subtraction of the divisor. The program consisted of 17&nbsp;instructions and ran for 52&nbsp;minutes before reaching the correct answer of 131,072, after the Baby had performed 3.5&nbsp;million operations (for an effective CPU speed of 1.1 [[instructions per second|kIPS]]). The successive approximations to the answer were displayed as a pattern of dots on the output [[cathode-ray tube|CRT]] which mirrored the pattern held on the Williams tube used for storage.