Editing History of computing hardware (section)

===Electromechanical computers===
{{Further|Mechanical computer#Electro-mechanical computers}}
The era of modern computing began with a flurry of development before and during World War II. Most digital computers built in this period were built with electromechanical – electric switches drove mechanical relays to perform the calculation. These mechanical components had a low operating speed due to their mechanical nature and were eventually superseded by much faster all-electric components, originally using [[vacuum tube]]s and later [[transistor]]s.

The [[Z2 (computer)|Z2]] was one of the earliest examples of an electric operated digital [[computer]] built with electromechanical relays and was created by civil engineer [[Konrad Zuse]] in 1940 in Germany. It was an improvement on his earlier, mechanical [[Z1 (computer)|Z1]]; although it used the same mechanical [[computer memory|memory]], it replaced the arithmetic and control logic with electrical [[relay]] circuits.<ref name="Part 4 Zuse">{{cite web |url=https://www.epemag.com/zuse/part4a.htm|title=Part 4: Konrad Zuse's Z1 and Z3 Computers|last=Zuse|first=Horst |work=The Life and Work of Konrad Zuse|publisher=EPE Online |access-date=2008-06-17 |archive-url=https://web.archive.org/web/20080601210541/http://www.epemag.com/zuse/part4a.htm |archive-date = 2008-06-01}}</ref>

In the same year, electro-mechanical devices called [[bombe]]s were built by British [[cryptologist]]s to help decipher [[Germany|German]] [[Enigma machine|Enigma-machine]]-encrypted secret messages during [[World War II]]. The bombe's initial design was created in 1939 at the UK [[Government Code and Cypher School]] at [[Bletchley Park]] by [[Alan Turing]],{{sfn|Smith|2007|p=60}} with an important refinement devised in 1940 by [[Gordon Welchman]].{{sfn|Welchman|1984|p=77}} The engineering design and construction was the work of [[Harold Keen]] of the [[British Tabulating Machine Company]]. It was a substantial development from a device that had been designed in 1938 by [[Polish Cipher Bureau]] cryptologist [[Marian Rejewski]], and known as the "[[Bomba (cryptography)|cryptologic bomb]]" ([[Polish language|Polish]]: ''"bomba kryptologiczna"'').

[[File:Z3 Deutsches Museum.JPG|thumb|left|Replica of [[Konrad Zuse|Zuse]]'s [[Z3 (computer)|Z3]], the first fully automatic, digital (electromechanical) computer]]
In 1941, Zuse followed his earlier machine up with the [[Z3 (computer)|Z3]],<ref name="Part 4 Zuse"/> the world's first working [[electromechanical]] [[Computer programming|programmable]], fully automatic digital computer.<ref>{{cite news|title=A Computer Pioneer Rediscovered, 50 Years On |newspaper=The New York Times |url=https://www.nytimes.com/1994/04/20/news/20iht-zuse.html |date=20 April 1994 |access-date=2017-02-16 |archive-date=2016-11-04 |archive-url=https://web.archive.org/web/20161104051054/http://www.nytimes.com/1994/04/20/news/20iht-zuse.html|url-status=live}}</ref> The Z3 was built with 2000 [[relay]]s, implementing a 22-[[bit]] [[Word (computer architecture)|word length]] that operated at a [[clock rate|clock frequency]] of about 5–10&nbsp;[[Hertz|Hz]].{{sfn|Zuse|1993|p=55}} Program code and data were stored on punched [[celluloid|film]]. It was quite similar to modern machines in some respects, pioneering numerous advances such as [[floating-point arithmetic|floating-point numbers]]. Replacement of the hard-to-implement decimal system (used in [[Charles Babbage]]'s earlier design) by the simpler [[binary number|binary]] system meant that Zuse's machines were easier to build and potentially more reliable, given the technologies available at that time.<ref>{{cite web |url=https://www.crash-it.com/crash/index.php?page=73 |archive-url=https://web.archive.org/web/20080318184915/http://www.crash-it.com/crash/index.php?page=73 |url-status=dead |archive-date=2008-03-18 |title=Zuse |work=Crash! The Story of IT}}</ref> The Z3 was proven to have been a [[Turing machine|Turing-complete machine]] in 1998 by [[Raúl Rojas]].<ref>{{Cite book|last=Rojas|first=Raúl|title=How to Make Zuse's Z3 a Universal Computer |date=1998 |citeseerx=10.1.1.37.665}}</ref> In two 1936 [[patent]] applications, Zuse also anticipated that machine instructions could be stored in the same storage used for data—the key insight of what became known as the [[von Neumann architecture]], first implemented in 1948 in America in the [[Mechanical computer#Electro-mechanical computers|electromechanical]] [[IBM SSEC]] and in Britain in the fully electronic [[Manchester Baby]].<ref>{{cite journal |title=Electronic Digital Computers |journal=Nature |last1=Williams |first1=F. C. |last2=Kilburn |first2=T. |date=25 September 1948 |volume=162 |issue=4117 |page=487 |bibcode=1948Natur.162..487W |doi=10.1038/162487a0 |s2cid=4110351 |doi-access=free }}</ref>

Zuse suffered setbacks during World War II when some of his machines were destroyed in the course of [[Allies of World War II|Allied]] bombing campaigns. Apparently his work remained largely unknown to engineers in the UK and US until much later, although at least IBM was aware of it as it financed his post-war startup company in 1946 in return for an option on Zuse's patents.

In 1944, the [[Harvard Mark I]] was constructed at IBM's Endicott laboratories.{{sfn|Da Cruz|2008}} It was a similar general purpose electro-mechanical computer to the Z3, but was not quite Turing-complete.