ENIAC, short for Electronic Numerical Integrator And
Computer, was the first purely electronic,
Turing-complete, digital
computer capable of being reprogrammed to solve a full range of computing
problems, although earlier computers had been built with some
of these properties. ENIAC was designed and built to calculate
artillery
firing tables for the
U.S. Army's
Ballistic Research Laboratory. The contract was signed on June 5, 1943 and Project PX was constructed by the University of Pennsylvania's Moore School of Electrical Engineering from July, 1943. It was unveiled on February 14, 1946 at Penn, having cost almost $500,000.
ENIAC was shut down on
November 9,
1946 for a refurbishment and a memory upgrade,
and was transferred to
Aberdeen Proving Ground,
Maryland in
1947. There, on
July 29 of that year, it was turned on and would be in
continuous operation until 11:45 p.m. on
October 2,
1955.
ENIAC was conceived and designed by
John Mauchly and
J. Presper Eckert of the
University of Pennsylvania. The team of design engineers assisting the
development included
Bob Shaw (function tables),
Chuan Chu (divider/square-rooter),
Kite Sharpless (master
programmer),
Arthur Burks (multiplier),
Harry Huskey (reader/printer), and
Jack Davis (accumulators). ENIAC's physical size was massive compared to modern PC standards. It contained 17,468 vacuum tubes, 7,200 crystal diodes, 1,500 relays, 70,000 resistors, 10,000 capacitors and around 5 million hand-soldered joints. It weighed 30 short tons (27 t), was roughly 8.5 feet by 3 feet by 80 feet (2.6 m by 0.9 m by 26 m), took up 680 square feet (63 m²), and consumed 150 kW of power.
Input was possible from an IBM
card reader, while an IBM card punch was used for output. These cards could be
used to produce printed output offline using an
IBM
accounting machine, probably the
IBM 405. Some electronics experts predicted that tube failures would occur so frequently that the machine would never be useful. This prediction turned out to be partially correct: several tubes burned out almost every day, leaving it nonfunctional about half the time. Special high-reliability tubes were not available until 1948.
|
Most of these failure, however, occurred during the warm-up and cool-down periods, when the tube heaters and cathodes were under the most thermal stress. The the simple )if expensive) expedient of never turning the machines off, the engineers reduced ENIAC's tube failures to the more acceptable rate of one tube every two days.
According to a 1989 interview with Eckert the continuously failing tubes story
was therefore mostly a myth: "We had a tube fail about every two days and we
could locate the problem within 15 minutes."
Eckert and Mauchly took the experience they gained and
founded the
Eckert-Mauchly
Computer Corporation, producing their first computer,
BINAC,
in
1949 before being acquired by
Remington Rand in
1950 and renamed as their
UNIVAC
division. ENIAC was a one-of-a-kind design and was never repeated. The freeze on design in 1943 meant that the computer had a number of shortcomings which were not included in the design, notably the inability to store a program. John von Neumann, who was consulting for the Moore School on the EDVAC (the ENIAC's successor computer for the BRL) and sat in on the Moore School meetings at which the stored program concept was elaborated, wrote up an incomplete set of notes (First Draft of a Report on the EDVAC) intended to be used as an internal memorandum describing, elaborating, and couching in formal logical language the ideas developed in the meetings.
Herman Goldstine distributed copies of the
First Draft to a number of government and educational institutions, spurring
widespread interest in the construction of a new generation of electronic
computing machines, including
EDSAC and
SEAC. |