Electronic general purpose computer

ENIAC emerged in 1945 Philadelphia because the U.S. Army needed to calculate artillery firing tables faster than human computers could manage. Each new gun required thousands of trajectory calculations accounting for wind, temperature, elevation, and muzzle velocity—work that took a skilled mathematician 20 hours per trajectory. With war consuming ammunition faster than ballistics tables could be produced, the Army funded an audacious proposal from John Mauchly and J. Presper Eckert at the Moore School of Electrical Engineering.

The machine they built was a monument to the vacuum tube era's possibilities and limitations. ENIAC contained 18,000 vacuum tubes, 7,200 crystal diodes, 6,000 relays, 70,000 resistors, and roughly 5 million hand-soldered joints. It filled a 50-by-30-foot room, weighed 30 tons, and consumed 150 kilowatts of power. But it could execute 5,000 additions per second—orders of magnitude faster than any previous calculating device.

Six women mathematicians—Jean Jennings, Marlyn Wescoff, Ruth Lichterman, Betty Snyder, Frances Bilas, and Kay McNulty—programmed ENIAC by physically rewiring its patch panels and setting its thousands of switches. They taught themselves from blueprints and circuit diagrams, then wrote the operating manual. Programming a single problem could take weeks of cable rearrangement.

ENIAC was formally dedicated on February 15, 1946, its existence revealed on the front page of The New York Times. The press dubbed it a 'Giant Brain.' The $487,000 project (about $7 million in 2024 dollars) had arrived too late to help with the war, but it proved that electronic general-purpose computation was possible.

The machine operated until 1955, its tasks evolving from ballistics to weather simulation to calculations for the hydrogen bomb. Mauchly and Eckert left Penn to found the company that would produce UNIVAC, making 'computer' a household word. ENIAC's architecture, while quickly superseded by stored-program designs, established that electronic computation could tackle any problem reducible to mathematics—the keystone insight that launched the digital age.