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Mechanical computer
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<h2 id="examples">Examples</h2> <ul><li><a href="/facts/Antikythera_mechanism/GHqvxCwR">Antikythera mechanism</a>, c. 100 <a href="/facts/Before_Christ/NmQwnQNj">BC</a> – A mechanical <a href="/facts/Astronomical_clock/8yaTPexw">astronomical clock</a>.</li> <li><a href="/facts/Cosmic_Engine/npEcuVbf">Cosmic Engine</a>, 1092 – <a href="/facts/Su_Song/npEcuVbf">Su Song</a>'s <a href="/facts/Hydraulics/KSIqLovc">hydro-mechanical</a> <a href="/facts/Astronomical_clock/8yaTPexw">astronomical</a> <a href="/facts/Clock_tower/jtdLDPXY">clock tower</a> invented during the <a href="/facts/Song_dynasty/FxV5bXS5">Song dynasty</a>, which featured the use of an early <a href="/facts/Escapement/8AgmCy7C">escapement</a> mechanism applied to clockwork.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a><a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a><a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a><a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a></li> <li><a href="/facts/Al-Jazari/ycMzl2tU">Castle clock</a>, 1206 – <a href="/facts/Al-Jazari/ycMzl2tU">Al-Jazari</a>'s castle clock, a <a href="/facts/Hydropower/Adx1E5ha">hydropowered</a> mechanical astronomical clock, has been described as the earliest <a href="/facts/Computer_programming/QmSsFnu0">programmable</a> analog computer.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a><a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a><a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a></li> <li>The <a href="/facts/Astrarium/AcD6GSbX">Astrarium</a> was a complex <a href="/facts/Astronomical_clock/8yaTPexw">astronomical clock</a> built in 1348 by <a href="/facts/Giovanni_Dondi_dell%2527Orologio/hvw02xMT">Giovanni Dondi dell'Orologio</a>. 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.<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a></li> <li><a href="/facts/Pascal%2527s_calculator/cMx8uB3w">Pascaline</a>, 1642 – <a href="/facts/Blaise_Pascal/Huy5LenL">Blaise Pascal</a>'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.</li> <li><a href="/facts/Stepped_Reckoner/kx62puql">Stepped Reckoner</a>, 1672 – <a href="/facts/Gottfried_Wilhelm_Leibniz/cTc2er83">Gottfried Wilhelm Leibniz</a>'s mechanical calculator that could add, subtract, multiply, and divide.</li> <li><a href="/facts/Difference_Engine/9extR8lB">Difference Engine</a>, 1822 – <a href="/facts/Charles_Babbage/T3jklQcd">Charles Babbage</a>'s mechanical device to calculate <a href="/facts/Polynomial/Lzak8VVx">polynomials</a>.</li> <li><a href="/facts/Analytical_Engine/Ts9xduLI">Analytical Engine</a>, 1837 – A later <a href="/facts/Charles_Babbage/T3jklQcd">Charles Babbage</a> device that could be said to encapsulate most of the elements of modern computers.</li> <li><a href="/facts/Odhner_Arithmometer/vEfE2UpA">Odhner Arithmometer</a>, 1873 – <a href="/facts/W._T._Odhner/suyEP8rq">W. T. Odhner</a>'s calculator who had millions of clones manufactured until the 1970s.</li> <li><a href="/facts/Ball-and-disk_integrator/XdcIJpuv">Ball-and-disk integrator</a>, 1886 – <a href="/facts/William_Thomson%2c_1st_Baron_Kelvin/LTIxG1jV">William Thomson</a> used it in his Harmonic Analyser to measure tide heights by calculating coefficients of a Fourier series.</li> <li><a href="/facts/Dumaresq/vdFCIqmq">Dumaresq</a>, 1902 – Royal Navy fire control computer</li> <li><a href="/facts/Percy_Ludgate/PIyqyEqH">Percy Ludgate</a>'s 1909 Analytical Machine – The 2nd of only two mechanical <a href="/facts/Analytical_Engine/Ts9xduLI">Analytical Engines</a> ever designed.</li> <li><a href="/facts/Dreyer_Fire_Control_Table/0VzyP3jJ">Dreyer Fire Control Table</a>, 1911 – Royal Navy fire control computer</li> <li><a href="/facts/Marchant_Calculator/WQs6WTeW">Marchant Calculator</a>, 1918 – Most advanced of the mechanical calculators. The key design was by <a href="/facts/Carl_Friden/5oI9APLR">Carl Friden</a>.</li> <li><a href="/facts/Admiralty_Fire_Control_Table/F4FGDvK1">Admiralty Fire Control Table</a>, 1922 – Royal Navy advanced fire control computer.[<i>dubious – discuss</i>]</li> <li>István Juhász Gamma-Juhász (<a href="/facts/Director_(military)/WB8M6K03">gun director</a>)<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a><a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a><a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a> (early 1930s)</li> <li><a href="/facts/Kerrison_Predictor/vINIrKbf">Kerrison Predictor</a> ("late 1930s"?)</li> <li><a href="/facts/Z1_(computer)/LDe34zlW">Z1</a>, 1938 (ready in 1941) – Konrad Zuse's mechanical calculator (although part imprecisions hindered its function)<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a></li> <li><a href="/facts/Mark_I_Fire_Control_Computer/B7s7BHyM">Mark I Fire Control Computer</a>, deployed by the <a href="/facts/United_States_Navy/xYK0fUou">United States Navy</a> during <a href="/facts/World_War_II/2efV5L1U">World War II</a> (1939 to 1945) and up to 1969 or later.</li> <li><a href="/facts/Curta_calculator/3H8cqpq0">Curta calculator</a>, 1948</li> <li><a href="/facts/MONIAC/q1DLqtsm">MONIAC</a>, 1949 – An <a href="/facts/Analog_computer/3NhYoCML">analog computer</a> used to model or simulate the <a href="/facts/UK_economy/R1UvrASA">UK economy</a>.</li> <li><a href="/facts/Voskhod_Spacecraft_%2522Globus%2522_IMP_navigation_instrument/To28TvqV">Voskhod Spacecraft "Globus" IMP navigation instrument</a>, early 1960s</li> <li><a href="/facts/Digi-Comp_I/6YnccLXT">Digi-Comp I</a>, 1963 – An educational 3-bit digital computer</li> <li><a href="/facts/Digi-Comp_II/Kr7haFQv">Digi-Comp II</a>, mid 1960s – A rolling ball digital computer</li> <li><a href="/facts/Automaton/SXtErQr2">Automaton</a> – Mechanical devices that, in some cases, can store data and perform calculations, and perform other complicated tasks.</li> <li><a href="/facts/Turing_Tumble/yrA1URwA">Turing Tumble</a>, 2017 – An educational Turing-complete computer partially inspired by the Digi-Comp II.</li> <li><a href="/facts/Slide_calculator/Nm1Yro9z">Slide calculator</a>, around 1845 - Also known as Addiator, is a mechanical calculator capable of addition and subtraction using a carry mechanism.</li></ul> <h2 id="punch-card-data-processing">Punch card data processing</h2> <p class="note">Main article: <a href="/facts/Unit_record_equipment/xkRvng9j">Unit record equipment</a></p> <p>Starting at the end of the nineteenth century, well before the advent of electronic <a href="/facts/Computers/SQe1aK05">computers</a>, data processing was performed using <a href="/facts/Electromechanics/0D5gkXko">electromechanical</a> machines collectively referred to as unit record equipment, electric accounting machines (EAM) or <a href="/facts/Tabulating_machine/ppepdpHw">tabulating machines</a>. By 1887, Herman Hollerith had worked out the basis for a mechanical system of recording, compiling and tabulating census facts.<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a> "Unit record" data processing equipment uses <a href="/facts/Punchcard/44WsPulQ">punchcards</a> to carry information on a one-item-per-card basis.<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a><a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a> 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 <a href="/facts/Punched_card/44WsPulQ">punched cards</a> 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.<a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a> This progression, or flow, from machine to machine was often planned and documented with detailed <a href="/facts/Flowchart/BtNXBfUG">flowcharts</a>.<a class="footnote-ref" id="fnref:18" href="#fn:18"><sup>18</sup></a> 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 <a href="/facts/Plugboard/fE3HX8tS">plugboard</a>, <a href="/facts/Plugboard/fE3HX8tS">control panel</a>, or <a href="/facts/Powers-Samas/FSSqSTgf">connection box</a>. </p> <h2 id="electro-mechanical-computers">Electro-mechanical computers</h2> <p class="note">Main category: Electro-mechanical computers</p> <p>Early electrically powered computers constructed from <a href="/facts/Switch/vqbNDgYm">switches</a> and <a href="/facts/Relay_logic/eEs4FXVn">relay logic</a> rather than <a href="/facts/Vacuum_tube/VHd1BNLq">vacuum tubes</a> (thermionic valves) or <a href="/facts/Transistor/Bmr8zwL0">transistors</a> (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. </p> <table><tbody><tr><th>Name</th><th>Country</th><th>Year</th><th>Remarks</th><th>Reference</th></tr><tr><td><a href="/facts/APEXC/DpwJ3nKH">Automatic Relay Computer</a></td><td><a href="/facts/UK/kuPAILt2">UK</a></td><td>1948</td><td><a href="/facts/Andrew_Donald_Booth/5Rnt1oKI">The Booths</a>, experimental</td><td><a class="footnote-ref" id="fnref:19" href="#fn:19"><sup>19</sup></a></td></tr><tr><td><a href="/facts/ARRA_(computer)/luKXDvCS">ARRA</a></td><td><a href="/facts/Netherlands/y8xn5stT">Netherlands</a></td><td>1952</td><td>experimental</td><td></td></tr><tr><td><a href="/facts/BARK_(computer)/Gnn2jcPd">BARK</a></td><td><a href="/facts/Sweden/u3qC7lyj">Sweden</a></td><td>1952</td><td>experimental</td><td></td></tr><tr><td><a href="/facts/FACOM-100/WK6ShAGs">FACOM-100</a></td><td><a href="/facts/Japan/U5mz0SRT">Japan</a></td><td>1954</td><td><a href="/facts/Fujitsu/6e5gvNSa">Fujitsu</a> commercial</td><td><a class="footnote-ref" id="fnref:20" href="#fn:20"><sup>20</sup></a></td></tr><tr><td><a href="/facts/FACOM-128/kvY6z3dq">FACOM-128</a></td><td>Japan</td><td>1956</td><td>commercial</td><td><a class="footnote-ref" id="fnref:21" href="#fn:21"><sup>21</sup></a></td></tr><tr><td><a href="/facts/Harwell_computer/KhB3oARw">Harwell computer</a></td><td>UK</td><td>1951</td><td>later known as WITCH</td><td></td></tr><tr><td><a href="/facts/Harvard_Mark_I/0d0yAVjb">Harvard Mark I</a></td><td><a href="/facts/United_States/P0sCdLe5">United States</a></td><td>1944</td><td>"IBM Automatic Sequence Controlled Calculator"</td><td></td></tr><tr><td><a href="/facts/Harvard_Mark_II/lG0fBmTh">Harvard Mark II</a></td><td>USA</td><td>1947</td><td>"Aiken Relay Calculator"</td><td></td></tr><tr><td><a href="/facts/IBM_SSEC/hofkk46I">IBM SSEC</a></td><td>USA</td><td>1948</td><td></td><td></td></tr><tr><td><a href="/facts/Imperial_College/SoXBRyax">Imperial College</a> Computing Engine (ICCE)</td><td>UK</td><td>1951</td><td>Electro-mechanical<a class="footnote-ref" id="fnref:22" href="#fn:22"><sup>22</sup></a></td><td><a class="footnote-ref" id="fnref:23" href="#fn:23"><sup>23</sup></a><a class="footnote-ref" id="fnref:24" href="#fn:24"><sup>24</sup></a><a class="footnote-ref" id="fnref:25" href="#fn:25"><sup>25</sup></a></td></tr><tr><td><a href="/facts/Office_of_Naval_Research/qKug0oD2">Office of Naval Research</a> ONR Relay Computer</td><td>USA</td><td>1949</td><td>6-bit, drum storage, but electro-mechanical relay ALU based on <a href="/facts/ERA_1101/m1uC2XsI">Atlas</a>, formerly Navy cryptology computer ABEL</td><td><a class="footnote-ref" id="fnref:26" href="#fn:26"><sup>26</sup></a><a class="footnote-ref" id="fnref:27" href="#fn:27"><sup>27</sup></a><a class="footnote-ref" id="fnref:28" href="#fn:28"><sup>28</sup></a><a class="footnote-ref" id="fnref:29" href="#fn:29"><sup>29</sup></a></td></tr><tr><td>OPREMA</td><td><a href="/facts/East_Germany/PwI902Q6">East Germany</a></td><td>1955</td><td>Commercial use at Zeiss Optical in Jena</td><td><a class="footnote-ref" id="fnref:30" href="#fn:30"><sup>30</sup></a></td></tr><tr><td>RVM-1</td><td><a href="/facts/Soviet_Union/m7wWsPto">Soviet Union</a></td><td>1957</td><td><a href="/facts/Alexander_Kronrod/Px81GUEq">Alexander Kronrod</a></td><td><a class="footnote-ref" id="fnref:31" href="#fn:31"><sup>31</sup></a></td></tr><tr><td><a href="/facts/SAPO_(computer)/sjDTKXV1">SAPO</a></td><td><a href="/facts/Czechoslovakia/9A6Kzmr0">Czechoslovakia</a></td><td>1957</td><td></td><td></td></tr><tr><td><a href="/facts/Simon_(computer)/nxkzA5Yh">Simon</a></td><td>USA</td><td>1950</td><td>Hobbyist logic demonstrator magazine article</td><td></td></tr><tr><td><a href="/facts/Z2_(computer)/fmrzzY6I">Z2</a></td><td><a href="/facts/Germany/paluuWBX">Germany</a></td><td>1940</td><td><a href="/facts/Konrad_Zuse/yrvbaEg3">Konrad Zuse</a></td><td></td></tr><tr><td><a href="/facts/Z3_(computer)/JNPXGqDp">Z3</a></td><td>Germany</td><td>1941</td><td>Zuse</td><td></td></tr><tr><td><a href="/facts/Z4_(computer)/RNjK5G7f">Z4</a></td><td>Germany</td><td>1945</td><td>Zuse</td><td></td></tr><tr><td><a href="/facts/Z5_(computer)/NkKPda95">Z5</a></td><td>Germany</td><td>1953</td><td>Zuse</td><td></td></tr><tr><td><a href="/facts/Z11_(computer)/Io77XL2K">Z11</a></td><td>Germany</td><td>1955</td><td>Zuse, commercial</td><td></td></tr><tr><td><a href="/facts/Bell_Labs/fKP5Gk0H">Bell Labs</a> Model I</td><td>USA</td><td>1940</td><td><a href="/facts/George_Stibitz/M6pUBsqx">George Stibitz</a>, "Complex Number Calculator", 450 relays and <a href="/facts/Crossbar_switch/fSDXkMzf">crossbar switches</a>, demonstrated remote access 1940, used until 1948</td><td><a class="footnote-ref" id="fnref:32" href="#fn:32"><sup>32</sup></a></td></tr><tr><td>Bell Labs Model II</td><td>USA</td><td>1943</td><td>"Relay Interpolator", used for wartime work, shut down 1962</td><td><a class="footnote-ref" id="fnref:33" href="#fn:33"><sup>33</sup></a></td></tr><tr><td>Bell Labs Model III</td><td>USA</td><td>1944</td><td>"Ballistic Computer", used until 1949</td><td><a class="footnote-ref" id="fnref:34" href="#fn:34"><sup>34</sup></a></td></tr><tr><td>Bell Labs Model IV</td><td>USA</td><td>1945</td><td>Navy "Mark 22 Error Detector", used until 1961</td><td><a class="footnote-ref" id="fnref:35" href="#fn:35"><sup>35</sup></a></td></tr><tr><td>Bell Labs <a href="/facts/Model_V/IfWE4EaQ">Model V</a></td><td>USA</td><td>1946, 1947</td><td>Two units delivered, general-purpose, built in trigonometric functions, floating-point arithmetic</td><td><a class="footnote-ref" id="fnref:36" href="#fn:36"><sup>36</sup></a></td></tr><tr><td>Bell Labs <a href="/facts/Model_V/IfWE4EaQ">Model VI</a></td><td>USA</td><td>1949</td><td>General purpose, simplified Model V with several enhancements</td><td></td></tr><tr><td>Unnamed cryptanalysis multiplier</td><td>UK</td><td>1937</td><td><a href="/facts/Alan_Turing/klov9b6g">Alan Turing</a></td><td><a class="footnote-ref" id="fnref:37" href="#fn:37"><sup>37</sup></a><a class="footnote-ref" id="fnref:38" href="#fn:38"><sup>38</sup></a></td></tr></tbody></table> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Analog_computer/3NhYoCML">Analog computer</a></li> <li><a href="/facts/Billiard-ball_computer/bNd0C6xH">Billiard-ball computer</a></li> <li><a href="/facts/Domino_computer/1pxQUtmb">Domino computer</a></li> <li><a href="/facts/History_of_computing_hardware/83xXSmuW">History of computing hardware</a></li> <li><a href="/facts/List_of_pioneers_in_computer_science/XlurWBLL">List of pioneers in computer science</a></li> <li><a href="/facts/Mechanical_calculator/As7HE5dB">Mechanical calculator</a></li> <li><a href="/facts/Spirule/PHASdGw7">Spirule</a></li> <li><a href="/facts/Tide-Predicting_Machine_No._2/Imlo2sLw">Tide-Predicting Machine No. 2</a></li> <li><a href="/facts/Turing_completeness/73goop44">Turing completeness</a></li></ul> <h2 id="external-links">External links</h2> <ul><li><a href="https://www.youtube.com/watch?v=vVgc8ksstyg">Electro-mechanical Harwell computer in action</a></li> <li><a href="https://www.youtube.com/watch?v=_j544ELauus">1958 FACOM 128B Japanese Relay Computer, still working!</a> on <a href="/facts/YouTube_video_(identifier)/db276jst">YouTube</a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Hall, Loura (2016-04-01). "Automaton Rover for Extreme Environments (AREE)". NASA. Retrieved 2017-08-29. <a href="https://www.nasa.gov/feature/automaton-rover-for-extreme-environments-aree" target="_blank">https://www.nasa.gov/feature/automaton-rover-for-extreme-environments-aree</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Needham, Volume 4, Part 2, 445. <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Needham, Volume 4, Part 2, 448. <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Bodde, 140. <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Fry, 10. <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>"Machines of the East". Ancient Discoveries. Season 3. Episode 10. History Channel. Archived from the original on 2021-12-21. Retrieved 2008-09-07. <a href="https://www.youtube.com/watch?v=-60niJUZjEU" target="_blank">https://www.youtube.com/watch?v=-60niJUZjEU</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Howard R. Turner (1997), Science in Medieval Islam: An Illustrated Introduction, p. 184, University of Texas Press, ISBN 0-292-78149-0 <a href="/wiki/University_of_Texas_Press" target="_blank">/wiki/University_of_Texas_Press</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>Donald Routledge Hill, "Mechanical Engineering in the Medieval Near East", Scientific American, May 1991, pp. 64–9 (cf. Donald Routledge Hill, Mechanical Engineering Archived 2007-12-25 at the Wayback Machine) <a href="/wiki/Donald_Routledge_Hill" target="_blank">/wiki/Donald_Routledge_Hill</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>Abrams, Melanie (2018-02-16). "'The Beauty of Time'". The New York Times. ISSN 0362-4331. Retrieved 2022-06-04. <a href="https://www.nytimes.com/2018/02/16/style/watches-clocks-mbandf-breuget.html" target="_blank">https://www.nytimes.com/2018/02/16/style/watches-clocks-mbandf-breuget.html</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Kovács, Győző (2012), Tatnall, Arthur (ed.), "Hungarian Scientists in Information Technology", Reflections on the History of Computing, IFIP Advances in Information and Communication Technology, vol. 387, Berlin, Heidelberg: Springer Berlin Heidelberg, pp. 292–294, doi:10.1007/978-3-642-33899-1_18, ISBN 978-3-642-33898-4, retrieved 2022-06-23 <a href="978-3-642-33898-4" target="_blank">978-3-642-33898-4</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>Weibel, Peter (17 May 2005). Beyond Art: A Third Culture: A Comparative Study in Cultures, Art and Science in 20th Century Austria and Hungary. Springer. pp. 304–305. ISBN 9783211245620. <a href="9783211245620" target="_blank">9783211245620</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>Hebime (2016-07-05). "Hungarian Gamma-Juhász predictor". WT Live. <a href="https://live.warthunder.com/post/457384/en/" target="_blank">https://live.warthunder.com/post/457384/en/</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>"Z3 from FOLDOC". foldoc.org. Retrieved 2020-07-02. <a href="http://foldoc.org/Z3" target="_blank">http://foldoc.org/Z3</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p>General Information Manual: An Introduction to IBM Punched Card Data Processing. IBM. p. 1. <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li> <li id="fn:15"><p>Janda, Kenneth (1965). Data Processing. Northwestern University Press. p. 47. <a href="https://archive.org/details/dataprocessingap00jand" target="_blank">https://archive.org/details/dataprocessingap00jand</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li> <li id="fn:16"><p>McGill, Donald A.C. (1962). Punched Cards, Data Processing for Profit Improvement. McGraw-Hill. p. 29. <a href="#fnref:16" class="footnote-back-ref">↩</a></p></li> <li id="fn:17"><p>Machine Functions (PDF). International Business Machines Corp. 1957. 224-8208-3. <a href="http://www.bitsavers.org/pdf/ibm/punchedCard/Training/224-8208-3_Machine_Functions_Mar61.pdf" target="_blank">http://www.bitsavers.org/pdf/ibm/punchedCard/Training/224-8208-3_Machine_Functions_Mar61.pdf</a> <a href="#fnref:17" class="footnote-back-ref">↩</a></p></li> <li id="fn:18"><p>Flow Charting and Block Diagramming Techniques (PDF). 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