During WWII, the U.S. Ballistics Research Laboratory was handling the complex calculations of range tables that were needed for new artillery. In 1942, physicist John Mauchly proposed an all-electronic calculating machine in a memorandum entitled “The Use of High Speed Vacuum Tube Devices for Calculating.”
ENIAC (Electronic Numerical Integrator And Computer), developed from 1943 -1945, became the first large-scale computer to run at electronic speed without being slowed by any mechanical parts. Completed in 1946, ENIAC had 18,000 vacuum tubes, 70,000 resistors, 6,000 switches, and 10,000 capacitors. Able to perform 5000 additions per second, ENIAC was much faster than any existing device of the time.
Thinking beyond its military applications, Mauchly realized the ENIAC technology could be applied to the private sector. In 1946, Mauchly and his chief engineer J. Presper Eckert designed the first general-purpose computer for commercial use: UNIVAC.