ENIAC filled a room with 17,000 vacuum tubeAn electronic component using evacuated glass tubes — predated transistors in radios, TVs, and early computers.s and computed artillery trajectories thousands of times faster than human calculators. Programmers rewired panels and set switches to change programs — no stored programA design where instructions and data share memory — programs can be loaded and changed without rewiring hardware. yet, but it proved electronic computation at scale was possible. The War Department had announced the machine on February 14; the dedication dinner and demonstration followed on February 15.

ENIAC was among the first large-scale electronic computers to operate as a reprogrammable digital machine.

It demonstrated that computation could be automated electronically — a foundation for later stored-programA design where instructions and data share memory — programs can be loaded and changed without rewiring hardware. designs.