ENIAC (1964)
The patent on the ENIAC, generally recognized as the first true digital computer, was the very first computer patent in history. It took nearly 20 years for examiners to grant it in 1964, but it was voided just nine years later. A 1973 landmark federal court case -- Honeywell vs. Sperry Rand -- put the invention of the electronic digital computer in the public domain because the court recognized an earlier prototype (the little-known Atanasoff computer) and John Atanasoff, not John Mauchly, as the inventor of the first electronic computer.
