History of computing hardware: Difference between revisions

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In the first half of the 20th century, [[analog computer]]s were considered by many to be the future of computing. These devices used the continuously changeable aspects of physical phenomena such as [[Electrical network|electrical]], [[Mechanics|mechanical]], or [[hydraulic]] quantities to [[Scientific modelling|model]] the problem being solved, in contrast to [[digital computer]]s that represented varying quantities symbolically, as their numerical values change. As an analog computer does not use discrete values, but rather continuous values, processes cannot be reliably repeated with exact equivalence, as they can with [[Turing machine]]s.{{sfn|Chua|1971|pp=507–519}}

The first modern analog computer was a [[tide-predicting machine]], invented by [[William Thomson, 1st BaronLord Kelvin|Sir William Thomson]], later Lord Kelvin, in 1872. It used a system of pulleys and wires to automatically calculate predicted tide levels for a set period at a particular ___location and was of great utility to navigation in shallow waters. His device was the foundation for further developments in analog computing.<ref name="stanf">{{cite encyclopedia |encyclopedia=Stanford Encyclopedia of Philosophy |title=The Modern History of Computing|year=2017 |publisher=Metaphysics Research Lab, Stanford University |url=https://plato.stanford.edu/entries/computing-history/ |access-date=2014-01-07 |archive-date=2010-07-12 |archive-url=https://web.archive.org/web/20100712072148/http://plato.stanford.edu/entries/computing-history/|url-status=live}}</ref>

The [[differential analyser]], a mechanical analog computer designed to solve differential equations by integration using wheel-and-disc mechanisms, was conceptualized in 1876 by [[James Thomson (engineer)|James Thomson]], the brother of the more famous Lord Kelvin. He explored the possible construction of such calculators, but was stymied by the limited output torque of the [[ball-and-disk integrator]]s.<ref>{{cite web |first=Ray |last=Girvan |title=The revealed grace of the mechanism: computing after Babbage |work=Scientific Computing World |date=May–June 2003 |url=https://www.scientific-computing.com/scwmayjun03computingmachines.html |archive-url=https://web.archive.org/web/20121103094710/http://www.scientific-computing.com/scwmayjun03computingmachines.html |archive-date=3 November 2012}}</ref> In a differential analyzer, the output of one integrator drove the input of the next integrator, or a graphing output.