The first electronic general-purpose computer, ENIAC (electronic numerical integrator and computer), was formally announced on February 15, 1946. The project had been heavily veiled before its first announcement, although its construction contract had been signed by the United States Army on June 5, 1943.

Code-named “Project PX” at the University of Pennsylvania’s Moore School of Electrical Engineering in Philadelphia where it was constructed, the Turing-complete digital computer was capable of being reprogrammed to solve a full range of computing problems and designed to calculate artillery firing tables for the United States Army’s Ballistic Research Laboratory, intended for use during World War II.

However, it took approximately one year to design ENIAC, and another 18 months to build, so by the time ENIAC was completed, WWII was over. By then, others had taken interest in ENIAC and its capabilities would not go to waste. John von Neumann, a mathematician working on the hydrogen bomb at Los Alamos, for example, became aware of the computer. The first test problem run on ENIAC was computation for the hydrogen bomb, not artillery tables as intended.

ENIAC’s timeline would become important in a legal dispute between Honeywell and Sperry Rand regarding the Atanasoff–Berry Computer (ABC), prototyped in 1939. That dispute lead to patents for the ENIAC being declared invalid.

In November 1946, ENIAC was shut down for a refurbishment and a memory upgrade. It was then transferred to Aberdeen Proving Ground, Maryland, in 1947. On July 29, it was turned on and was in continuous operation until October 2, 1955.

Called the “giant brain,” ENIAC took up an entire room. In the mid 1990s, the Moore School created “ENIAC-on-a-Chip,” a single 7.44×5.29-mm chip that held all of ENIAC’s functionality.

Parts of the computer are now on display at several museums across the globe, including the Smithsonian in Washington, DC, and the Computer History Museum in Mountain View, CA.

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Editor’s note: This article was originally posted on February 15, 2013 and edited on February 15, 2019.