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[[Beeld:Eniac.jpg|right|300px|thumb|Glen Beck (agter) en Betty Snyder (voor) programmeer die ENIAC.]]
'''ENIAC''', Engels vir '''Electronic Numerical Integrator And Computer''',<ref>{{cite book | last = Goldstine | first = Herman H. | authorlink = Herman Goldstine | title = The Computer: from Pascal to von Neumann | year = 1972 | publisher = Princeton University Press | location = Princeton, New Jersey | id = ISBN 0-691-02367-0 }}</ref> was die eerste algemeen doelgerigtedoeligge elektroniese rekenaar. Dit was die eerste hoë-spoed, [[Turingvolledigheid|Turingvolledige]], digitale rekenaar wat herprogrammeergeherprogrammeer kon word om 'n reeks rekenkundigerekenmatige probleme op te los, <ref>Shurkin, Joel, ''Engines of the Mind: The Evolution of the Computer from Mainframes to Microprocessors'', 1996, ISBN 0-393-31471-5</ref> terwyl vroërevroër masjiene net sekere van die eienskappe gehadgahad het. Die ENIAC was ontwerp en gebou deur die [[VSA]]-weermag om artillerie vuur tabelle te bereken.
Die ENIAC was van onmiddelike belang. Met die aankondiging daarvan in 1946 was daarna verwys as die "Enorme Brein" deur die media. Dit het gespog met 'n spoed duisend keer vinniger as elektro-meganiese masjiene, 'n sprong in rekenkundige krag wat geen enkele masjien nog kon bereik nie. Die wiskundige krag, gepaard met algemeen-doelige programmering, het wetenskaplikes en industrialiste baie opgewonde gehad. Die uitvinders het die nuwe idees versprei deur 'n reeks [[Moore School Lectures|lesings]] aan te bied oor rekenaar argitektuur.
Die ENIAC se ontwerpontwer en konstruksie was gefinansieërgefinasier deur die Verenigde[[Vereenigde State Weermag]] gedurende die [[Tweede Wêreldoorlog]].
Die konstruksie kontrak was geteken op [[5 Junie]], [[1943]], en werk op die rekenaar hetwas, die volgende maand, in die geheim begin onder die skuilnaam "Projek PX" deur die [[Universiteit van Pennsylvania]] se [[Moore Skool van Elektriese Ingenieurswese]]. Die volledige masjien was onthul op [[14 Februarie]], [[1946]] by die Universiteit van Pennsylvania, en het $500,000 gekos. Dit is formeel deur die V.S. Weermag Artillerie afdeling in diens geneemaanvaar in Julie 1946. ENIAC was afgeskakelafgesit op [[9 November]], [[1946]] vir opknappings en 'n geheue opgradering, en was geskuifverplaas na [[Aberdeen Toets Grond]], [[Maryland]] in 1947. Daar, op [[29 Julie]], [[1947]], is dit weer aangeskakel en was in voortdurendevoortsettende gebruik tot 11:45 pm, [[2 Oktober]], [[1955]].
[[Image:Two women operating ENIAC.gif|right|thumbnail|300px|thumb|Programmeerders [[Jean Bartik|Betty Jean Jennings]] (links) en [[Frances Spence|Fran Bilas]] (regs) besig op die ENIAC se hoof kontrole paneel by die [[Moore Skool van Elektriese Ingenieurswese]]. (V.S. Weermag foto van die argiewe van die ARL Tegniese biblioteek )]]
| id = QA76.W5 1956
| isbn =
}}</ref> Die span ontwerp ingenieurs wat die ontwikkeling bygestaan en gehelp het sluit in [[Robert F. Shaw|Bob Shaw]] (funksie tabelle), [[Chuan Chu]] (deler/vierkantswortelaar), [[Kite Sharpless]] (meester programmeerder), [[Arthur Burks]] (vermenigvuldiger), [[Harry Huskey]] (leser/drukker, [[Jack Davis (ingenieur)|Jack Davis]] (versamelaars) en [[Iredell Eachus Jr.]]<ref>{{cite web| url=http://www.upenn.edu/gazette/0506/obits.html | title=Gazette Alumni: Obituaries (Iredell Eachus Jr.) | toegangsdatum=2008-09-11 | quote=According to his family, J. Presper Eckert EE’41 GEE’43 Hon’64 was his best friend in college. As a U.S. Naval ensign during World War II, he received a direct commission from President [[Franklin D. Roosevelt]] assigning him to naval-research work in Washington, where he was involved in developing technology for weapons systems, radar targeting systems, and communications devices. He then became a member of the ENIAC team at Penn. According to the Main Line Times, he felt that the logic circuits of the machine were more discovered than invented. }}</ref>
==Beskrywing==
Die ENIAC was 'n modulere [[rekenaar]], saamgestel uit individuele panele om verskillende funksies te verrig. Twintig van hierdie modules was versamelaars, wat nie net kon optel en aftrek nie, maar kon ook 'n tien-syfer [[desimale]] nommer stoor in sy geheue. Nommers was aangegee tussen twee eenhede oor 'n aantal algemeen-doelige busse, of borde, soos dit genoem was. Om die hoë spoed te bereik moes die panele die nommers ontvang en aanstuur, bereken, die antwoord stoor, en die volgende stap aktiveer - alles sonder bewegende onderdeleparte. Die sleutel tot sy veelsydigheid was die vermoë om te vertak; dit kon verskillende bewerkings, wat afhanklik was van die berekende resultaat, aktiveer
Naas die spoed, was die mees merkwaardige kenmerkding omtrent die ENIAC die grootte en kompleksiteit daarvan. ENIAC het 17,468 [[vakuum buisvakuumbuis]]e, 7,200 kristal [[diode]]s, 1,500 [[aflosser]]s, 70,000 [[resistor]]s, 10,000 [[kondensatorkapasitor]]se en ongeveer 5 miljoen handge[[soldeer]]de skarnieresoldeerlasse. Dit het 30 [[kort ton]]ne (27 t) geweeg, was rofweg 8.5 voet by 3 voet by 80 voet (2.6 m by 0.9 m by 26 m), het 680 vierkante voet (63 m²) op geneem, en het 150 [[Kilowatt|kW]] krag verbruik.<ref>{{cite web | url=http://ed-thelen.org/comp-hist/BRL-e-h.html | title=http://ed-thelen.org/comp-hist/BRL-e-h.html | accessdate=2008-05-23 }}</ref> Invoer was moontlik deur 'n IBM kaart leser, en 'n IBM kaartpons was gebruik vir die uitvoer. Hierdie kaarte kon gebruik word om 'n aflyn gedrukte uitvoer te lewer deur 'n [[IBM]] berekeningsmasjien te gebruik, by voorbeeld die [[IBM 405]].
ENIAC het tien-posisie [[ringteller]]s gebruik om syfers te stoor; elke syfer het 36 vakuum buise gebruik, 10 daarvan was tweevoudige triodes wat die [[Flip-flop(elektronies)|flip-floppe]] van die ringteller. Rekenkunde was uitgevoer deur die impulse "te tel" met die ringtellers en genereer dan dra-impulse as die teller "rond spring", die idee was om in elektronika die bewerking van die syfer wiele van 'n meganiese optel masjien, na te jaag. ENIAC het twintig tien-syfer getekende [[Akkumulator (bereken)|akkumulator]] wat [[tien se komplement]] voorstelling gebruik het en kon 5,000 eenvoudige optel en aftrek bewerkings doen tussen enige van hulle an 'n bron (bv, nog 'n akkumulator, of 'n konstante seintoestel) elke sekond. Dit was moontlik om 'n paar akkumulators te koppel en gelyktydig te hardloop, so die top spoed van die bewerking was moontlik baie hoër weens die parallelle bewerkings.
Dit was moontlik om die oordra van een akkumulator na 'n ander akkumulator te bedraad om met [[dubbele presisie]] rekenkundige bewerkings te doen
It was possible to wire the carry of one accumulator into another acccumulator to perform [[double precision]] arithmetic, but the accumulator carry circuit timing prevented the wiring of three or more for higher precision. The ENIAC used four of the accumulators, controlled by a special ''Multiplier'' unit, to perform up to 385 multiplication operations per second. The ENIAC also used five of the accumulators, controlled by a special ''Divider/Square-Rooter'' unit, to perform up to forty division operations per second or three [[square root]] operations per second.
The other nine units in ENIAC were the ''Initiating Unit'' (which started and stopped the machine), the ''Cycling Unit'' (used for synchronizing the other units), the ''Master Programmer'' (which controlled 'loop' sequencing), the ''Reader'' (which controlled an IBM punch card reader), the ''Printer'' (which controlled an IBM punch card punch), the ''Constant Transmitter'', and three ''Function Tables''.
[[Image:Classic shot of the ENIAC.jpg|right|thumbnail|300px|thumb|Cpl. Herman Goldstein (foreground) sets the switches on one of the ENIAC's function tables at the [[Moore School of Electrical Engineering]]. (U.S. Army photo)]]
The references by Rojas and Hashagen or (Wilkes 1956)<ref name="autogenerated1">Wilkes</ref> give more details about the times for operations, which differ somewhat from those stated above. The basic machine cycle was 200 [[microseconds]] (20 cycles of the 100 kHz clock in the cycling unit), or 5,000 cycles per second for operations on the 10-digit numbers. In one of these cycles, ENIAC could write a number to a register, read a number from a register, or add/subtract two numbers. A multiplication of a 10-digit number by a ''d''-digit number (for ''d'' up to 10) took ''d''+4 cycles, so a 10- by 10-digit multiplication took 14 cycles, or 2800 microseconds—a rate of 357 per second. If one of the numbers had fewer than 10 digits, the operation was faster. Division and square roots took 13(''d''+1) cycles, where ''d'' is the number of digits in the result (quotient or square root). So a division or square root took up to 143 cycles, or 28,600 microseconds—a rate of 35 per second. (Wilkes 1956:20<ref name="autogenerated1" /> states that a division with a 10 digit quotient required 6 milliseconds.) If the result had fewer than ten digits, it was obtained faster.
===Reliability===
ENIAC used common [[tube socket#Octal|octal-base]] radio tubes of the day; the decimal [[Accumulator (computing)|accumulators]] were made of [[6SN7]] [[flip-flop (electronics)|flip-flops]], while 6L7s, 6SJ7s, 6SA7s and 6AC7s were used in logic functions. Numerous [[6L6]]s and [[6V6]]s served as line drivers to drive pulses through cables between rack assemblies.
ENIAC used ten-position [[ring counter]]s to store digits; each digit used 36 vacuum tubes, 10 of which were the dual triodes making up the [[Flip-flop (electronics)|flip-flops]] of the ring counter. Arithmetic was performed by "counting" pulses with the ring counters and generating carry pulses if the counter "rapped around", the idea being to emulate in electronics the operation of the digit wheels of a mechanical [[adding machine]]. ENIAC had twenty ten-digit signed [[Accumulator (computing)|accumulators]] which used [[ten's complement]] representation and could perform 5,000 simple addition or subtraction operations between any of them and a source (''e.g.'', another accumulator, or a constant transmitter) every second. It was possible to connect several accumulators to run simultaneously, so the peak speed of operation was potentially much higher due to parallel operation.
== Verwysings ==
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