ENIAC was one of the first fully electronic programmable computers. ENIAC is short for Electronic Numerical Integrator and Computer. Engineers built ENIAC under contract with the United States War Department during World War II (1939-1945). The computer became operational on Feb. 14, 1946. ENIAC was originally designed to compute firing tables for the United States Army. Firing tables were charts used by soldiers to calculate firing angles for artillery shells.
ENIAC could work on more than just firing tables. Because the computer could be reprogrammed, it could solve many different kinds of mathematical problems. Users programmed ENIAC by setting switches and by using wires to connect sockets laid out in arrangements called plugboards. Individual sockets and switches were labeled for different instructions. Connecting setups for individual instructions enabled ENIAC to run a complete program.
ENIAC could add about 5,000 pairs of numbers per second. It used decimal (base 10) arithmetic, becoming one of the first and only machines to do so. In contrast, virtually all modern computers use binary (base 2) arithmetic, which calculates using only the digits 1 and 0.
ENIAC was a huge machine. It weighed about 30 tons (27 metric tons). It took up about as much floor space as an average house. The computer contained 17,468 vacuum tubes; 1,500 electronic relays; and 5 million hand-soldered joints. It consumed 150,000 watts of power.
Two Americans—the electrical engineer J. Presper Eckert, Jr., and the physicist John W. Mauchly—designed ENIAC. The computer was built in 2 1/2 years at the University of Pennsylvania’s Moore School of Engineering. ENIAC’s design influenced many other early computers in the 1940’s and early 1950’s.
