Mauchly and Eckert filed for a patent covering their Electronic Numerical Integrator and Computer, built at the University of Pennsylvania to calculate artillery firing tables for the U.S. Army. The 30-ton machine, completed in 1945, used over 17,000 vacuum tubes and could perform calculations thousands of times faster than earlier electromechanical devices.
ENIAC filled a 1,800-square-foot room and consumed 150 kilowatts of power, so much that rumors circulated (probably apocryphally) that its operation dimmed lights in Philadelphia. Programming it required physically rewiring plugboards and setting switches, a laborious process largely carried out by a team of women mathematicians, including Kay McNulty, Betty Jennings, and others, whose contributions went largely uncredited for decades.
The patent filed on this day would become one of the most consequential and contested in computing history. Sperry Rand, which acquired rights to the patent, attempted to collect royalties from virtually every computer manufacturer for years, until a 1973 federal court ruling in Honeywell v. Sperry Rand invalidated the patent, finding that Mauchly and Eckert had derived key concepts from earlier work by physicist John Atanasoff, effectively placing the fundamental architecture of the electronic computer into the public domain.
That court decision reshaped the emerging computer industry, ensuring no single company could claim a monopoly on digital computing's foundational technology, and it restored, at least in the historical record, recognition to Atanasoff's earlier and less heralded Atanasoff-Berry Computer.
Key people: John Mauchly, J. Presper Eckert