The machine itselfENIAC was a beast of a computer. It weighed 30 tons and filled an entire classroom. It was the epitome of an overwhelming “Giant Brain” of the sort that spawned countless science fiction movies. It had to wait for a major upgrade before its program moved from tedious patch cords into lightning-fast electronic memory, and since microchips nor even transistors existed, it instead used more than 17,000 vacuum tubes. There was only one ENIAC ever built. But it was the first fully electronic general-purpose computer. It was used mainly for military and scientific research applications such as aeronautics, ballistics, meteorology, and nuclear weapons. It remained in operation until 1955.
The links on this page describe how ENIAC was built, how it worked, and what it was like to operate it.