{{short description|Computer built from mechanical components such as levers and gears}} {{More citations|date=May 2026}} [[File:De-Te-We-mp3h0651.jpg|thumb|Hamman Manus R mechanical computer, produced in Germany by the DeTeWe company between 1953 and 1959]]
A '''mechanical computer''' is a computer built from mechanical components such as levers and gears rather than electronic components. The most common examples are adding machines and mechanical counters, which use the turning of gears to increment output displays. More complex examples could carry out multiplication and division—Friden used a moving head which paused at each column—and even differential analysis. One model, the Ascota 170 accounting machine sold in the 1960s, calculated square roots.
{{clarification needed span|text=Mechanical computers can be either ''analog'', using continuous or smooth mechanisms such as curved plates or slide rules for computations; or ''discrete'', which use mechanisms like pinwheels and gears.|reason=The uncited passage is at odds with the universal understanding of the definition for an "analog computer", which deals with data in an "analog" rather than (binary) "digital" form. It must either be authoritatively cited as is, or reworded to conform with the generally understood definition of "analog computer" (as laid out at the WP article for it).|date=March 2024}}
Mechanical computers reached their zenith during World War II, when they formed the basis of complex bombsights including the Norden, as well as the similar devices for ship computations such as the US Torpedo Data Computer or British Admiralty Fire Control Table. Noteworthy are mechanical flight instruments for early spacecraft, which provided their computed output not in the form of digits, but through the displacements of indicator surfaces. From Yuri Gagarin's first spaceflight in 1961 until 2002, every crewed Soviet and Russian spacecraft Vostok, Voskhod and Soyuz was equipped with a ''Globus'' instrument showing the apparent movement of the Earth under the spacecraft through the displacement of a miniature terrestrial globe, plus latitude and longitude indicators.
Mechanical computers continued to be used into the 1960s, but had steadily been losing ground to digital computers since their advent. By the mid-1960s dedicated electronic calculators with cathode-ray tube output emerged. The next step in the evolution occurred in the 1970s, with the introduction of inexpensive handheld electronic calculators. The use of mechanical computers declined in the 1970s and was rare by the 1980s.{{citation needed|date=May 2026}} According to a mechanical engineer who operated the German corvette ''Hiddensee'' while it was examined by the United States Navy, the Soviets still made use of mechanical computers to calculate the target coordinates for their missiles in the late 80s.<ref>{{cite magazine |last1=Langreth |first1=Robert |editor1-last=Stepler |editor1-first=Richard L. |title=Voyage of the Hiddensee |magazine=Popular Science |date=August 1995 |volume=247 |issue=2 |page=80 |url=https://books.google.com/books?id=eotsjCkfREUC&pg=PA80 |access-date=21 May 2026 |publisher=Times Mirror Magazines |location=New York City |issn=0161-7370 |via=Google Books}}</ref>
In 2016, NASA announced that its Automaton Rover for Extreme Environments program would use a mechanical computer to operate in the harsh environmental conditions found on Venus.<ref>{{Cite news|url=https://www.nasa.gov/feature/automaton-rover-for-extreme-environments-aree|title=Automaton Rover for Extreme Environments (AREE)|last=Hall|first=Loura|date=2016-04-01|work=NASA|access-date=2017-08-29|language=en}}</ref>
==Examples== right|thumb|Curta Calculator * Antikythera mechanism, c. 100 BC – A mechanical astronomical clock. * Cosmic Engine, 1092 – Su Song's hydro-mechanical astronomical clock tower invented during the Song dynasty, which featured the use of an early escapement mechanism applied to clockwork.<ref name="needham volume 4 445">Needham, Volume 4, Part 2, 445.</ref><ref name="needham volume 4 448">Needham, Volume 4, Part 2, 448.</ref><ref name="bodde 140">Bodde, 140.</ref><ref name="fry 10">Fry, 10.</ref> * Castle clock, 1206 – Al-Jazari's castle clock, a hydropowered mechanical astronomical clock, has been described as the earliest programmable analog computer.<ref name="Ancient Discoveries">{{Cite episode|title=Machines of the East|url=https://www.youtube.com/watch?v=-60niJUZjEU |archive-url=https://ghostarchive.org/varchive/youtube/20211221/-60niJUZjEU |archive-date=2021-12-21 |url-status=live|access-date=2008-09-07|series=Ancient Discoveries|network=History Channel|season=3|number=10}}{{cbignore}}</ref><ref>Howard R. Turner (1997), ''Science in Medieval Islam: An Illustrated Introduction'', p. 184, University of Texas Press, {{ISBN|0-292-78149-0}}</ref><ref name=Hill2>Donald Routledge Hill, "Mechanical Engineering in the Medieval Near East", ''Scientific American'', May 1991, pp. 64–9 (cf. Donald Routledge Hill, [http://home.swipnet.se/islam/articles/HistoryofSciences.htm Mechanical Engineering] {{webarchive|url=https://web.archive.org/web/20071225091836/http://home.swipnet.se/islam/articles/HistoryofSciences.htm |date=2007-12-25 }})</ref> * The Astrarium was a complex astronomical clock built in 1348 by Giovanni Dondi dell'Orologio. The Astrarium had seven faces and 107 moving parts; it could show and predict the positions of the sun, the moon, stars and the five planets then known, as well as religious feast days.<ref>{{Cite news |last=Abrams |first=Melanie |date=2018-02-16 |title='The Beauty of Time' |language=en-US |work=The New York Times |url=https://www.nytimes.com/2018/02/16/style/watches-clocks-mbandf-breuget.html |access-date=2022-06-04 |issn=0362-4331}}</ref> * Pascaline, 1642 – Blaise Pascal's arithmetic machine primarily intended as an adding machine which could add and subtract two numbers directly, as well as multiply and divide by repetition. * Stepped Reckoner, 1672 – Gottfried Wilhelm Leibniz's mechanical calculator that could add, subtract, multiply, and divide. * Difference Engine, 1822 – Charles Babbage's mechanical device to calculate polynomials. * Analytical Engine, 1837 – A later Charles Babbage device that could be said to encapsulate most of the elements of modern computers. * Odhner Arithmometer, 1873 – W. T. Odhner's calculator who had millions of clones manufactured until the 1970s. * Ball-and-disk integrator, 1886 – William Thomson used it in his Harmonic Analyser to measure tide heights by calculating coefficients of a Fourier series. *Algebraic Machines, 1893 – Leonardo Torres Quevedo's analog calculating machines designed to solve algebraic equations and find roots of polynomials. They featured the Endless Spindle (Huso sin fin), a mechanism used to calculate logarithms mechanically with high precision.<ref name="MaquinasAlgebricasLTQ">Leonardo Torres. ''[https://books.google.com/books?id=Eo0NAQAAIAAJ Memoria sobre las máquinas algébricas: con un informe de la Real academia de ciencias exactas, fisicas y naturales]'', Misericordia, 1895.</ref><ref name="Thomas2008">{{Cite journal |last=Thomas |first=Federico |date=2008-08-01 |title=A short account on Leonardo Torres' endless spindle |url=https://www.sciencedirect.com/science/article/pii/S0094114X07001231 |journal=Mechanism and Machine Theory |publisher=IFToMM |volume=43 |issue=8 |pages=1055–1063 |doi=10.1016/j.mechmachtheory.2007.07.003 |issn=0094-114X|hdl=10261/30460 |hdl-access=free }}</ref><ref name="Gomez-JaureguiGutierrez-GarciaGonzález-RedondoIglesiasManchadoOtero2022">{{Cite journal |last1=Gomez-Jauregui |first1=Valentin |last2=Gutierrez-Garcia |first2=Andres |last3=González-Redondo |first3=Francisco A. |last4=Iglesias |first4=Miguel |last5=Manchado |first5=Cristina |last6=Otero |first6=Cesar |date=2022-06-01 |title=Torres Quevedo's mechanical calculator for second-degree equations with complex coefficients|journal=Mechanism and Machine Theory |publisher=IFToMM |volume=172 |issue=8|article-number=104830 |doi=10.1016/j.mechmachtheory.2022.104830|s2cid=247503677 |doi-access=free |hdl=10902/24391 |hdl-access=free }}</ref> * Dumaresq, 1902 – Royal Navy fire control computer * Percy Ludgate's 1909 Analytical Machine – The 2nd of only two mechanical Analytical Engines ever designed. * Dreyer Fire Control Table, 1911 – Royal Navy fire control computer * Marchant Calculator, 1918 – Most advanced of the mechanical calculators. The key design was by Carl Friden. * Admiralty Fire Control Table, 1922 – Royal Navy advanced fire control computer.{{dubious|reason=electromechanical|date=December 2022}} * István Juhász Gamma-Juhász (gun director)<ref>{{Citation |last=Kovács |first=Győző |title=Hungarian Scientists in Information Technology |date=2012 |url=https://hal.inria.fr/hal-01526814 |work=Reflections on the History of Computing |series=IFIP Advances in Information and Communication Technology |volume=387 |pages=292–294 |editor-last=Tatnall |editor-first=Arthur |place=Berlin, Heidelberg |publisher=Springer Berlin Heidelberg |doi=10.1007/978-3-642-33899-1_18 |isbn=978-3-642-33898-4 |access-date=2022-06-23|doi-access=free |url-access=subscription }}</ref><ref>{{Cite book |last1=Weibel |first1=Peter |url=https://books.google.com/books?id=xkk6U42Zl_sC&q=gamma+juhasz&pg=PA304 |title=Beyond Art: A Third Culture: A Comparative Study in Cultures, Art and Science in 20th Century Austria and Hungary |date=17 May 2005 |isbn=9783211245620 |pages=304–305|publisher=Springer }}</ref><ref>{{Cite web |last=Hebime |date=2016-07-05 |title=Hungarian Gamma-Juhász predictor |url=https://live.warthunder.com/post/457384/en/ |website=WT Live}}</ref> (early 1930s) * Kerrison Predictor ("late 1930s"?) * Z1, 1938 (ready in 1941) – Konrad Zuse's mechanical calculator (although part imprecisions hindered its function)<ref>{{Cite web|title=Z3 from FOLDOC|url=http://foldoc.org/Z3|access-date=2020-07-02|website=foldoc.org}}</ref> * Mark I Fire Control Computer, deployed by the United States Navy during World War II (1939 to 1945) and up to 1969 or later. * Curta calculator, 1948 * MONIAC, 1949 – An analog computer used to model or simulate the UK economy. * Voskhod Spacecraft "Globus" IMP navigation instrument, early 1960s * Digi-Comp I, 1963 – An educational 3-bit digital computer * Digi-Comp II, mid 1960s – A rolling ball digital computer * Automaton – Mechanical devices that, in some cases, can store data and perform calculations, and perform other complicated tasks. * Turing Tumble, 2017 – An educational Turing-complete computer partially inspired by the Digi-Comp II. * Slide calculator, around 1845 - Also known as Addiator, is a mechanical calculator capable of addition and subtraction using a carry mechanism.
==Punch card data processing== {{Main|Unit record equipment}} Starting at the end of the nineteenth century, well before the advent of electronic computers, data processing was performed using electromechanical machines collectively referred to as '''unit record equipment''', '''electric accounting machines''' ('''EAM''') or '''tabulating machines'''. By 1887, Herman Hollerith had worked out the basis for a mechanical system of recording, compiling and tabulating census facts.<ref>{{cite book |title= General Information Manual: An Introduction to IBM Punched Card Data Processing |publisher= IBM |page= 1}}</ref> "Unit record" data processing equipment uses punchcards to carry information on a one-item-per-card basis.<ref>{{cite book |author= Janda, Kenneth|title=Data Processing |url= https://archive.org/details/dataprocessingap00jand|url-access= registration|publisher= Northwestern University Press |year= 1965 |page = [https://archive.org/details/dataprocessingap00jand/page/47 47]}}</ref><ref> {{cite book |author= McGill, Donald A.C. |title = Punched Cards, Data Processing for Profit Improvement |publisher= McGraw-Hill |year= 1962 |page= 29}}</ref> Unit record machines came to be as ubiquitous in industry and government in the first two-thirds of the twentieth century as computers became in the last third. They allowed large volume, sophisticated data-processing tasks to be accomplished before electronic computers were invented and while they were still in their infancy. This data processing was accomplished by processing punched cards through various unit record machines in a carefully choreographed progression. Data on the cards could be added, subtracted and compared with other data and, later, multiplied as well.<ref>{{cite book |author= |url=http://www.bitsavers.org/pdf/ibm/punchedCard/Training/224-8208-3_Machine_Functions_Mar61.pdf |title=Machine Functions |publisher=International Business Machines Corp. |year=1957 |id=224-8208-3}}</ref> This progression, or flow, from machine to machine was often planned and documented with detailed flowcharts.<ref>{{cite book |author= |url=http://www.bitsavers.org/pdf/ibm/generalInfo/C20-8008-0_Flowcharting_Ref_Man_Sep59.pdf |title=Flow Charting and Block Diagramming Techniques |publisher=International Business Machines Corp. |year=1959 |id=/C20-8008-0}}</ref> All but the earliest machines had high-speed mechanical feeders to process cards at rates from around 100 to 2,000 per minute, sensing punched holes with mechanical, electrical, or, later, optical sensors. The operation of many machines was directed by the use of a removable plugboard, control panel, or connection box.
==Electro-mechanical computers== right|thumb|150px|Harwell Dekatron {{Main category|Electro-mechanical computers}} Early electrically powered computers constructed from switches and relay logic rather than vacuum tubes (thermionic valves) or transistors (from which later electronic computers were constructed) are classified as electro-mechanical computers. These varied greatly in design and capabilities, with some units capable of floating point arithmetic. Some relay-based computers remained in service after the development of vacuum-tube computers, where their slower speed was compensated for by good reliability. Some models were built as duplicate processors to detect errors, or could detect errors and retry the instruction. A few models were sold commercially with multiple units produced, but many designs were experimental one-off productions.
{| class="wikitable sortable" |- ! align=left | Name ! align=left | Country ! align=left | Year ! align=left class="unsortable" | Remarks ! align=left | Reference
|- valign=top style="border-bottom:1px solid #999;" | Automatic Relay Computer | UK | 1948 | The Booths, experimental |<ref>{{Cite book|url=https://books.google.com/books?id=AU28AAAAIAAJ&q=%22Automatic+Relay+Computer%22+booth&pg=PA62|title=Early British Computers: The Story of Vintage Computers and the People who Built Them|last=Lavington|first=Simon Hugh|date=1980|publisher=Manchester University Press|isbn=9780719008108|pages=62|language=en}}</ref> |- |ARRA | Netherlands |1952 | experimental | |- |BARK | Sweden |1952 |experimental | |- |ETL Mark I | Japan |1952 | experimental, asynchronous |<ref>Takahasi, H. (1980). Some important computers of Japanese design. Annals of the History of Computing, 2(4), 330-337.</ref> |- |FACOM-100 | Japan |1954 |Fujitsu commercial, asynchronous |<ref>{{cite web |url=http://museum.ipsj.or.jp/en/computer/dawn/0008.html |title=Fujitsu Facom 100 |access-date=2017-07-26}}</ref> |- |FACOM-128 |Japan |1956 |commercial |<ref>{{cite web |url=http://museum.ipsj.or.jp/en/computer/dawn/0012.html |title=FACOM 128A and 128B Relay Computers |access-date=2017-07-26}}</ref> |- |Harwell computer |UK |1951 |later known as WITCH | |- |Harvard Mark I | United States |1944 |"IBM Automatic Sequence Controlled Calculator" | |- |Harvard Mark II |USA |1947 |"Aiken Relay Calculator" | |- |IBM SSEC |USA |1948 | | |- |Imperial College Computing Engine (ICCE) |UK |1951 |Electro-mechanical<ref>{{Cite web|url=https://www.essex.ac.uk/people/brook29509/tony-brooker|title=Profile for Tony Brooker at the University of Essex|website=www.essex.ac.uk|access-date=2018-05-19}}</ref> |<ref>{{Cite news|url=http://wwwf.imperial.ac.uk/blog/videoarchive/from-the-arithmometer-to-electronic-arithmetic-1998/|title=From the Arithmometer to Electronic Arithmetic – 1998|date=2016-05-06|work=Imperial College Video Archive Blog|access-date=2018-05-14|language=en-US}} [https://www.youtube.com/watch?v=E-kf24HXLic&t=2295 Cited video fragment] from 38:15 to 38:32</ref><ref>{{Cite journal|date=April 1951|title=Relay Digital Computer, Imperial College, Univ. of London|url=https://apps.dtic.mil/sti/citations/AD0694600|journal=Digital Computer Newsletter|volume=3|issue=1|pages=4}}</ref><ref>{{Cite book|chapter-url=https://archive.org/details/FasterThanThought|title=Faster Than Thought|editor-first=B. V.|editor-last=Bowden |pages=161–164 (103–105)|chapter=11. The Imperial College Computing Engine}}</ref> |- |Office of Naval Research ONR Relay Computer |USA |1949 | 6-bit, drum storage, but electro-mechanical relay ALU based on Atlas, formerly Navy cryptology computer ABEL |<ref>{{Cite book|url=https://books.google.com/books?id=Mi8MhzheOokC&pg=PA95 |title=When Computers Went to Sea: The Digitization of the United States Navy|last=Boslaugh|first=David L.|year=2003|publisher=John Wiley & Sons|isbn=9780471472209|pages=95–96}}</ref><ref>{{Cite journal|date=April 1952|title=The ONR Relay Computer|url=https://apps.dtic.mil/sti/citations/AD0694604|journal=Digital Computer Newsletter |volume=4|issue=2|pages=2}}</ref><ref>{{cite book|url=https://archive.org/details/bitsavers_onrASurveyomputers1953_8778395|title=A survey of automatic digital computers|year=1953|publisher=Office of Naval Research, Dept. of the Navy|page=[https://archive.org/details/bitsavers_onrASurveyomputers1953_8778395/page/n80 75]}}</ref><ref>{{cite journal|last1=Wolf|first1=J. Jay|title=The Office of Naval Research Relay Computer|journal=Mathematics of Computation|date=1952|volume=6|issue=40|pages=207–212|doi=10.1090/S0025-5718-1952-0050393-0|issn=0025-5718|doi-access=free}}</ref> |- |OPREMA |East Germany |1955 |Commercial use at Zeiss Optical in Jena |<ref>{{Cite book|url=https://books.google.com/books?id=AcOKIXcaV8sC&q=oprema&pg=PA134|title=Red Prometheus: Engineering and Dictatorship in East Germany, 1945–1990|last=Augustine|first=Dolores L.|date=2007|publisher=MIT Press|isbn=9780262012362|pages=134|language=en}}</ref> |- |RVM-1 |Soviet Union |1957 |Nikolay Bessonov, Alexander Kronrod |<ref>[https://yandex.ru/patents/doc/SU91513A1_19510101 Н. И. Бессонов, Способ нахождения суммы произведений нескольких пар сомножителей на счетно-аналитической машине табулятор и устройство для осуществления способа. Авт. св-во SU91513, 01.01.1951.]</ref><ref>[https://yandex.ru/patents/doc/SU98799A1_19540101 Н. И. Бессонов, Релейный вычислительный автомат. Авт. св-во SU98799, 01.01.1954.]</ref><ref>[https://yandex.ru/patents/doc/SU217719A1_19680507 Н. И. Бессонов, Устройство для выборки групп разрядов числа и сдвига этих групп или всего числа на заданное число разрядов. Авт. св-во SU217719, 07.05.1968.]</ref><ref>[https://search.rsl.ru/ru/record/01010685205 Н. И. Бессонов. Релейная вычислительная машина РВМ. Дисс. канд. техн. наук, Акад. наук СССР. Теплотехн. лаборатория, Москва, 1958]</ref><ref>[https://urss.ru/cgi-bin/db.pl?lang=Ru&blang=ru&page=Book&id=34249&srsltid=AfmBOooCydbJ4R1rSinIDg77pY-cqPmh5f11_HRzGX0Tvjb8Z2WkQFxP А. С. Кронрод. Беседы о программировании. Изд. 3, URSS, 2006]</ref><ref>{{cite web |url=http://informatic.ugatu.ac.ru/resources/museum/english/pbm-1.htm |title=Relay Computer RVM-1 |access-date=2017-07-25 |archive-date=2018-06-19 |archive-url=https://web.archive.org/web/20180619170832/http://informatic.ugatu.ac.ru/resources/museum/english/pbm-1.htm |url-status=dead }}</ref> |- |SAPO |Czechoslovakia |1957 | | |- |Simon |USA |1950 | Hobbyist logic demonstrator magazine article | |- |Z2 |Germany |1940 |Konrad Zuse | |- |Z3 |Germany |1941 | Zuse | |- |Z4 | Germany | 1945 | Zuse | |- |Z5 |Germany |1953 | Zuse | |- |Z11 |Germany |1955 | Zuse, commercial | |- |Bell Labs Model I |USA |1940 | George Stibitz, "Complex Number Calculator", 450 relays and crossbar switches, demonstrated remote access 1940, used until 1948 |<ref name=":0">{{Cite book|url=https://books.google.com/books?id=8IXArCuNWy4C&q=bell+model&pg=PA197|title=Encyclopedia of Computer Science and Technology: Volume 3 – Ballistics Calculations to Box-Jenkins Approach to Time Series Analysis and Forecasting|last1=Belzer|first1=Jack|last2=Holzman|first2=Albert G.|last3=Kent|first3=Allen|date=1976-03-01|publisher=CRC Press|isbn=9780824722531|pages=197–200|language=en}}</ref> |- |Bell Labs Model II |USA |1943 | "Relay Interpolator", used for wartime work, shut down 1962 |<ref name=":0" /> |- |Bell Labs Model III |USA |1944 | "Ballistic Computer", used until 1949 |<ref name=":0" /> |- |Bell Labs Model IV |USA |1945 |Navy "Mark 22 Error Detector", used until 1961 |<ref name=":0" /> |- |Bell Labs Model V |USA |data-sort-value="1946"|1946, 1947 |Two units delivered, general-purpose, built in trigonometric functions, floating-point arithmetic |<ref name=":0" /> |- |Bell Labs Model VI |USA |1949 |General purpose, simplified Model V with several enhancements | |- |Unnamed cryptanalysis multiplier |UK |1937 |Alan Turing |<ref>{{Cite book|url=https://books.google.com/books?id=0IIsoRqw9hgC&q=Turing+1937+Multiplier&pg=PA46|title=Alan Turing: Life and Legacy of a Great Thinker|last=Teuscher|first=Christof|date=2004|publisher=Springer Science & Business Media|isbn=9783540200208|pages=46|language=en}}</ref><ref>{{Cite book|url=https://books.google.com/books?id=QnUPBAAAQBAJ&pg=PA175|title=Alan Turing: The Enigma: The Book That Inspired the Film "The Imitation Game"|last=Hodges|first=Andrew|date=2014-11-10|publisher=Princeton University Press|isbn=9781400865123|pages=175–177|language=en}}</ref> |}
==See also== * Analog computer * Billiard-ball computer * Domino computer * History of computing hardware * List of pioneers in computer science * Mechanical calculator * Spirule * Tide-Predicting Machine No. 2 * Turing completeness
==References== {{reflist}}
==External links== * [https://www.youtube.com/watch?v=vVgc8ksstyg Electro-mechanical Harwell computer in action] * {{youTube |title=1958 FACOM 128B Japanese Relay Computer, still working! |id=_j544ELauus }}
Category:Mechanical computers Category:Electro-mechanical computers