Builders: | J. Presper Eckert, John W. Mauchly. Also Arthur Burks,
Kite Sharpless, John Davis, Robert Shaw, and others
|
Place: | Moore School of Electrical Engineering, University of Pennsylvania,
Philadelphia. Later moved to the Ballistic Research Laboratory, Aber-
deen, Maryland.
|
Dates: | Proposed April, 1943; authorized June, 1943; completed by November,
1945; first problem run December, 1945.
Dedicated February 16, 1946; moved to Aberdeen November, 1946;
dismantled October 2, 1955. Parts now in various museums, including
the Smithsonian, Washington, D.C., and the Science Museum, London.
|
Cost: | $500,000 (exactly $486,804.22, according to Goldstine),
funded by the Army.
|
Technology: | Vacuum tubes for computing; electromechanical input and output:
card readers, card punches, printers; telephone relay buffer store.
|
Physical
specifications: |
40 panels, each 9' x 2' x 1', arranged in a U-shape; other units on
casters could be positioned at various places. 18,000 tubes, 1,500 relays.
80 different DC voltages, ranging from -920 to + 550 volts; main power
240 volts, 60 Hz. Power consumption: 150 kW, 80 kW for tube heaters,
45 kW for other electronic circuits, 5 kW for input/output devices, 20
kW for ventilating and cooling.
|
Architecture: | Word length: 10 decimal digits plus sign;
ten's complement for negative
numbers and subtraction; fixed decimal point-switch- selected;
multiplication by table look-up. Addition and subtraction done in
accumulators; separate unit for multiplication, division, and
square-rooting. Other units for cycling (timing), pulse generation, and programming.
Reckoners, ENIAC, page 0124
|
|
Memory: | 20 numbers in the accumulators: 100 read-only numbers in a function
table; other storage by punched cards; also twenty 10-digit constant switches.
|
Speed: | Pulse frequency, 100 kHz, or one pulse every 10 microseconds. Basic
cycle was one addition time, 20 pulses, or 200 microseconds (5,000 additions/second).
Multiplication time, 14 addition times, or 2,800 microseconds (357 multiplications/second). Division time varied, up to 38 divisions/second.
The ENIAC could be run at slower speeds, including a single pulse at a
time, or a single cycle at a time, for diagnostic purposes.
|
Programming: | Plugboards and switch settings. Full conditional branching and
subroutine capability; also the ability to perform parallel sequences of operations.
Slow to set up: a day or two for each new problem.
|
Input: | 80-channel IBM punched-card reader; could read 2 numbers/second.
|
Output: | Standard IBM printer. Each accumulator also had a bank of neon lights
showing its contents; at normal speeds these were of course illegible, but
at diagnostic speeds they could be read.
|
Miscellaneous: | Much of the metalwork and other physical construction done by
Livingston & Conway, Inc., a Philadelphia construction firm. Cooling
system designed and built by Eggly Engineers, also of Philadelphia. RCA
of Camden, New Jersey, supplied the tubes.
|