In 1946, the first large-scale electronic digital computer became operational. ENIAC (Electronic Numerical Integrator and Calculator) used a system of externally mounted switches and plugs to program it. The instrument was built by J. Presper Eckert Jr. and John Mauchly. The patent for the ENIAC was turned down, however, as it was judged as being derived from a prototype machine designed by Dr John Vincent Atanasoff, who also helped create the Atanasoff-Berry Computer. Work was also published this year detailing the concept of a stored-program successor to ENIAC (the EDVAC, to be completed in 1952).
