Difference between revisions of "Computing device"

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'''Computing devices''' are a more general class of devices which could perform complicated calculations than 'computers', the meaning of which is generally now 'stored-program computing device' (i.e. the control [[program]] is stored in [[memory]] that the computer can modify, allowing the program to change itself if it desires). They generally preceded the creation of computers (as defined above); although as Michael Williams observed, "If you add enough adjectives to a description you can always claim [a particular machine to be the 'first']."
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'''Computing devices''' are a more general class of devices which could perform complicated calculations than 'computers', the meaning of which is generally now 'stored-program computing device' (i.e. the control [[program]] is stored in [[memory]] that the computer can modify, allowing the program to change itself if it desires).
  
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==Notable early computing devices==
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Whether or not the ability to modify its own program is important, for something to be classified as a 'computer', can be debated; modern computers almost always run [[pure code]] (in part because [[self-modifying code]] can be difficult to understand and [[debug]]), so it is probably not critical; indeed, [[embedded system]]s usually use [[read-only memory|ROM]] for their program storage. On the other hand, program modifiability is a key aspect of classical [[Turing machine]]s; but it might be possible for a machine running out of ROM to [[emulator|emulate]] a Turing machine.
  
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Some of the first powerful computing devices were those of [[Charles Babbage]]: a prototype of the first, the [[Difference Engine]], was started in the 1820's, but never finished. (The Museum of Science recently built an actual difference engine, using a later design he created, but never attempted to build; it worked reasonably well.) His later proposed [[Analytical Engine]] (1870's) was the first ''programmable'' computing device, and a general-purpose one, but its program was fixed (in [[read-only memory]], effectively). His engines were all [[digital]], but entirely mechanical.
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Complex computing devices (i.e. things considerably more complex than a simple adding machines) generally preceded the creation of computers (as defined above); although as Michael Williams observed, "If you add enough adjectives to a description you can always claim [a particular machine to be the 'first']."
  
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Vannevar Bush created his Differential Analyzer at [[Massachusetts Institute of Technology|MIT]] in 1928–1931; it was an [[analog]] device, mostly mechanical. Many similar machines were then created in the US, UK, Norway, etc.
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==See also==
  
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Howard Aiken, inspired by Babbage's work, began the design of his [[Automatic Sequence Controlled Calculator]] in 1937; actually completed and used, it was a large programmable (but not stored program) electro-mechanical digital device. Later successors from IBM were entirely [[relay]]-based, not partially mechanical, as the ASCC was, and eventually (in the [[Selective Sequence Electronic Calculator]]) partly [[electronic]]. Very slightly later than the ASCC, the [[Bell Telephone Laboratories relay computing devices]] of [[George Stibitz]] were also entirely relay-based, and digital.
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* [[Notable early computing devices]]
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At about the same time, in 1938, [[John Vincent Atanasoff]] took the next step, and began the creation of the first [[electronic]] digital computing device, later called the [[Atanasoff–Berry Computer]]. It was not at all programmable; it could only solve systems of simultaneous equations. It was notable for having inspired [[John Mauchly]] when he later set out to build the [[ENIAC]]; and also for being the first digital electronic computing device to use [[capacitor]]-based memory - an approach to memory now ubiquitous in the [[Dynamic RAM]] of all modern computers.
 
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The [[Colossus]] digital electronic code-breaking devices of [[Tommy Flowers]], built in the UK during World War Two (construction of the first one started in 1943), were notable because they showed that large electronic computing devices could be made to operate reliably, because quite a few were produced, and because many of the post-War computer pioneers in the UK learned about the suitability of electronics for digital computing devices from them. They are often described as 'programmable', but this is incorrect - they had no program of any form, and they were not general-purpose; a better description is 'configurable'.
 
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Effectively the last step before true computers was the ENIAC, a large digital electronic computing device. As originally designed, it was only configurable, requiring considerable effort to re-configure it to perform a different computation (although it was general-purpose, unlike the Atanasoff–Berry Computer and Colossus). In 1947 an effort was started to re-configure it in a way that added a certain amount of programmability, via a program stored in the 'function-table switches' (originally intended as a ROM data source). Later, minor [[hardware]] modifications improved ENIACs efficiency when configured as a stored-program machine; it started to operate in that mode in 1948.
 
  
 
==Further reading==
 
==Further reading==
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* [https://www.gleech.org/first-computers Disambiguating the first computer]
 
* [https://www.gleech.org/first-computers Disambiguating the first computer]
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* [https://en.wikipedia.org/wiki/Colossus_computer Colossus computer] - a good and detailed description
 
  
 
[[Category: Early Computing Devices]]
 
[[Category: Early Computing Devices]]

Revision as of 02:27, 1 December 2023

Computing devices are a more general class of devices which could perform complicated calculations than 'computers', the meaning of which is generally now 'stored-program computing device' (i.e. the control program is stored in memory that the computer can modify, allowing the program to change itself if it desires).

Whether or not the ability to modify its own program is important, for something to be classified as a 'computer', can be debated; modern computers almost always run pure code (in part because self-modifying code can be difficult to understand and debug), so it is probably not critical; indeed, embedded systems usually use ROM for their program storage. On the other hand, program modifiability is a key aspect of classical Turing machines; but it might be possible for a machine running out of ROM to emulate a Turing machine.

Complex computing devices (i.e. things considerably more complex than a simple adding machines) generally preceded the creation of computers (as defined above); although as Michael Williams observed, "If you add enough adjectives to a description you can always claim [a particular machine to be the 'first']."

See also

Further reading

External links

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