Inventors of the Modern Computer
The ENIAC I
J. Presper Eckert & John W. Mauchly
"...With the advent of everyday use of elaborate calculations,
speed has become paramount to such a high degree that there is no machine
on the market today capable of satisfying the full demand of modern computational
methods." - from the ENIAC patent (U.S.#3,120,606), filed on June 26,
U.S. Army Photo
The ENIAC, in BRL building 328
1946, John Mauchly and John Presper Eckert developed the ENIAC I (Electrical
The U.S. military sponsored their research; they needed a calculating device
for writing artillery-firing tables (the settings used for different weapons
under varied conditions for target accuracy). The Ballistics Research Laboratory,
or BRL (the branch of the military responsible for calculating the tables),
heard about John Mauchly's research at the University of Pennsylvania's
Moore School of Electrical Engineering. Mauchly had previously created
several calculating machines, some with small electric motors inside. He
had begun designing (1942) a better calculating machine based on the work
of John Atanasoff that would use vacuum tubes
to speed up calculations.
May 31, 1943, the military commission on the new computer began; Mauchly
was the chief consultant and Eckert was the chief engineer. Eckert was
a graduate student studying at the Moore School when he met John Mauchly
in 1943. It took the team about one year to design the ENIAC and 18 months
and 500,000 tax dollars to build it. By that time, the war was over. The
ENIAC was still put to work by the military doing calculations for the
design of a hydrogen bomb, weather prediction, cosmic-ray studies, thermal
ignition, random-number studies and wind-tunnel design.
ENIAC contained 17,468 vacuum tubes, along with 70,000 resistors, 10,000
capacitors, 1,500 relays, 6,000 manual switches and 5 million soldered
joints. It covered 1800 square feet (167 square meters) of floor space,
weighed 30 tons, consumed 160 kilowatts of electrical power, and, when
turned on, caused the city of Philadelphia to experience brownouts.
one second, the ENIAC (one thousand times faster than any other calculating
machine to date) could perform 5,000 additions, 357 multiplications or
38 divisions. The use of vacuum tubes instead of switches and relays created
the increase in speed, but it was not a quick machine to re-program. Programming
changes would take the technicians weeks, and the machine always required
long hours of maintenance. As a side note, research on the ENIAC led to
many improvements in the vacuum tube.
1948, Dr. John Von Neumann made several modifications to the ENIAC. The
ENIAC had performed arithmetic and transfer operations concurrently, which
caused programming difficulties. Von Neumann suggested that switches control
code selection so pluggable cable connections could remain fixed. He added
a converter code to enable serial operation.
1946, Eckert and Mauchly started the Eckert-Mauchly Computer Corporation.
In 1949, their company launched the BINAC (BINary Automatic) computer that
used magnetic tape to store data.
1950, the Remington Rand Corporation bought the Eckert-Mauchly Computer
Corporation and changed the name to the Univac Division of Remington Rand.
Their research resulted in the UNIVAC (UNIVersal
Automatic Computer), an important forerunner of today's computers.
1955, Remington Rand merged with the Sperry Corporation and formed Sperry-Rand.
Eckert remained with the company as an executive and continued with the
company as it later merged with the Burroughs Corporation to become Unisys.
and Mauchly both received the IEEE Computer Society Pioneer Award in 1980.
11:45 p.m., October 2, 1955, with the power finally shut off, the ENIAC
Find biographies, interviews and photographs of J. Presper Eckert and
John W. Mauchly. Find more history and photographs of the ENIAC computer.
Inventors of the Modern Computer
Frederic Williams & Tom Kilburn
The Manchester Baby & Williams Tube
all artwork ©mary bellis
& "army photos"