John Mauchly - Patent Controversy

Patent Controversy

Mauchly and Eckert's patent on the ENIAC was invalidated by U.S. Federal Court decision in October, 1973 for several reasons. Some had to do with the time between publication (the First Draft) and the patent filing date (1947). The federal judge who presided over the case ruled that "the subject matter was derived" from the earlier Atanasoff–Berry Computer (ABC). This statement has become the center of a controversy.

Critics note that while the court said that the ABC was the first electronic digital computer, it did not define the term computer. It had originally referred to a person who computes, but was adapted to apply to a machine.

Critics of the court decision also note that there is, at a component level, nothing in common between the two machines. The ABC was binary; the ENIAC was decimal. The ABC used regenerative drum memory; The ENIAC used electronic decade counters. The ABC used its tubes to implement a binary serial adder while the ENIAC used tubes to implement a complete set of decimal operations. The ENIAC's general-purpose instruction set, together with the ability to automatically sequence through them, made it a general-purpose computer.

Proponents for the court decision emphasize that the testimony established that Mauchly definitely had complete access to Atanasoff's machine and the documents describing it. Letters he wrote to Atanasoff show that he was at one time at least considering building on Atanasoff's approach.

Mauchly consistently maintained that it was the use of high-speed electronic flip-flops in cosmic-ray counting devices at Swarthmore College that gave him the idea for computing at electronic speeds.