The receiver unit of the ENIAC calculator, c. 1946.

ENIAC, the Electronic Numerical Integrator Analyzer and Computer, was the first general purpose electronic calculator, and was designed by J Presper Eckert (1919-1995) and John W Mauchly (1907-1980) at the University of Pennsylvania, United States. ENIAC began during World War II as a classified military project referred to as Project PX. It began operation in 1946, and was used until 1955. ENIAC was originally used to work out shell trajectories, but was later used for calculations relating to H-bomb research. It is regarded as being the machine which laid the foundations of the modern computer industry, as it proved that high-speed digital computing was feasible using the valve technology of the time.