Electronic Numerical Integrator and Computer

computer (ENIAC) The second general-purpose electronic

digital computer and an ancestor of most computers in use

today. ENIAC was developed by Dr. John Mauchly and

J. Presper Eckert during World War II at the Moore School of

the University of Pennsylvania.

In 1940 Dr. John Vincent Atanasoff attended a lecture by

Mauchly and subsequently agreed to show him his computer, the

Atanasoff-Berry Computer (ABC), which was built between

1937-1942. Mauchly used ideas from the ABC in the design of

ENIAC, which was started in June 1943 and released publicly in

1946.

ENIAC was underwritten and its development overseen by

Lieutenant Herman Goldstine of the U.S. Army Ballistic

Research Laboratory (BRL). While the prime motivation for

constructing the machine was to automate the wartime

production of firing and bombing tables, the very first

program run on ENIAC was a highly classified computation

for Los Alamos. Later applications included weather

prediction, cosmic ray studies, wind tunnel design,

petroleum exploration, and optics.

ENIAC had 20 registers made entirely from vacuum tubes.

It had no other no memory as we currently understand it. The

machine performed an addition in 200 microseconds, a

multiplication in about three milliseconds, and a division

in about 30 milliseconds.

John von Neumann, a world-renowned mathematician serving on

the BRL Scientific Advisory Committee, soon joined the

developers of ENIAC and made some critical contributions.

While Mauchly, Eckert and the Penn team continued on the

technological problems, he, Goldstine, and others took up the

logical problems. In 1947, while working on the design for

the successor machine, EDVAC, von Neumann realized that

ENIAC's lack of a centralized control unit could be overcome

to obtain a rudimentary stored program computer.

Modifications were undertaken, that eventually led to an

instruction set of 92 "orders". Von Neumann also proposed

the fetch-execute cycle.

[R. F. Clippinger, "A Logical Coding System Applied to the

ENIAC", Ballistic Research Laboratory Report No. 673, Aberdeen

Proving Ground, MD, September 1948.

].

[H. H. Goldstine, "The Computer from Pascal to von Neumann",

Princeton University Press, 1972].

[K. Kempf, "Electronic Computers within the Ordnance Corps",

Aberdeen Proving Ground, MD, 1961.

].

[M. H. Weik, "The ENIAC Story", J. American Ordnance Assoc.,

1961. ].

(2002-06-03)