ENIAC

ENIAC , acronym of Electronic Numerical Integrator To analyze and Computer , is entirely the electronic first Ordinateur builds to be Turing-complete. It can be reprogrammed to solve a great number of calculative problems.

It is preceded in 1941 by the Z3, a programmable but still mechanical machine, and by the British computer Colossus. The ENIAC and Colossus use vacuum tubes.

History

The principle is an idea of John William Mauchly, professor of physics. Participant in a conference with the Ursinus College, it sees analysts producing range tables, it realizes that these calculations could be realized electronically. J. Presper Eckert solves the problems of engineering, the main thing being the lifespan of the electron tubes.

It is the American army which will finance and build the project for the needs for the research laboratory in ballistics. The computer is financed the May 17th 1943 under the name Project PX and is built with the Moore School off Electrical Engineering of the Université of Pennsylvania as from mid 1944. It is in February 1946 that it is operational then it is cut the November 9th 1946 to be renovated and its increased memory.

The February 14th 1946 it is revealed with the public with the Université of Pennsylvania to Philadelphia then is transferred to Aberdeen Proving Grounds, Maryland in 1947 when it is restarted on July 29th and begins calculations of the range tables. It continues to function until its stop in 1955. Today part of the machine is preserved at Université of Pennsylvania or a small museum is devoted to him

The ENIAC received the attention of the newspapers in particular because of its imposing size, but of a certain manner, it is not the fine flower of its era. Contrary to Z3 de Konrad Zuse (1941) or to MARK I of Howard $aiken (1944), it must be recâblé to carry out a new program. Moreover the ENIAC uses decimal and nonbinary registers.

Characteristics

The ENIAC uses closed counting chains with ten positions to record the figures. The arithmetic one is carried out by counting the pulsations with the rings and to generate pulsations when the meter makes a turn. The idea returns in fact to emulate by electronics the systems of wheel with mechanical figures of machine.

Its capacity is of 20 numbers with ten signed digits allowing each one to carry out 5.000 simple additions each second (for a total of 100.000 additions a second). It can on the other hand manage only 357 multiplications or 38 divisions a second.

Physically the ENIAC is a monster, it contains 17.468 vacuum tubes, 7.200 crystal diodes, 1.500 relays, 70.000 resistances, 10.000 condensing and approximately 5 million joints welded with the hand. Its weight is of 30 tons for dimensions of 2,4 X 0,9 X 30,5 meters occupying a surface of 167 square meters. Its consumption is of 160 kilowatts.

It uses vacuum tubes bases eight of them, the decimal accumulators are carried out with flip-failures 6SN7, whereas the switching functions use 6L7, 6SJ7, 6SA7 and 6AC7. Many a 6L6 and 6V6 is used as relay to convey the pulsations between the various racks of elements.

Certain experts in electronics predicted that the tubes would so frequently break down that the machine would be unusable. The prediction was only partially correct, of many tubes burned each day leaving the inoperative ENIAC half of time. More reliable lamps were not available before 1948, Eckert and Mauchly thus had to use tubes of standard quality. The majority of the problems involved in the tubes occur with starting or to the stopping of the machine because they are subjected has an important thermal stress. The simple fact never of not cutting the machine, makes it possible to the engineers to reduce the number of breakdowns to one or two tubes per day. More the long period of calculation without breakdown is reached in 1954 with 116 hours, which is a prowess taking into account the technology of the time.

The ENIAC functions until the October 2nd 1955. The architecture decided and frozen since 1943, does not make it possible to solve certain problems in particular the incapacity to record a program. However the ideas produced by this work and the impact on people such John von Neumann deeply influenced the development of the following computers (for example: EDVAC, EDSAC and SEAC. Certain improvements took place, in particular a primitive system making it possible to record a program in a memory in reading alone, an idea suggested by von Neumann. This last modification slowed down the computing speed of a factor six, but the duration of reprogramming spent several days to a few hours.

Ecker and Mauchly found a company, Eckert-Mauchly Computer Corporation, and produce the first computer in 1949: BINAC. The firm is repurchased the following by Remington Rand and re-elected year Univac.

See too

Generating of pseudo-random numbers, John Von Neumann implemented the first pseudo-random generator on the ENIAC

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