Judge declares the ENIAC patent invalid, October 19, 1973

-October 19, 2016

A legal dispute between Honeywell and Sperry Rand led to patents for the ENIAC (Electronic Numerical Integrator And Computer) being declared invalid on October 19, 1973, belatedly crediting physicist John Atanasoff with developing the first electronic digital computer, the Atanasoff-Berry Computer (ABC).



Built at Iowa State University by Atanasoff and graduate student Clifford Berry, the ABC was not programmable, as it was designed only to solve systems of linear equations. It was successfully tested in 1942. When Atanasoff left for World War II assignments, work on the ABC was discontinued.

J Presper Eckert and John Mauchly became the first to patent a digital computing device, the ENIAC, in 1964. Mauchly had examined the ABC in June 1941, and Isaac Auerbach, a former student of Mauchly's, alleged that it influenced the later work on ENIAC. Mauchly denied that allegation.

In 1967 Honeywell sued Sperry Rand in an attempt to break its ENIAC patents, arguing the ABC constituted prior art. The United States District Court for the District of Minnesota agreed and found that the ENIAC patent was a derivative of Atanasoff's invention.

The court ruling stated that while the extent to which Mauchly drew on Atanasoff's ideas was unknown, it could be inferred that Mauchly, at minimum, saw the potential significance of the ABC technology which may have led him to propose a similar, electronic solution.

The ABC was a modest technology, but it was first to use binary digits to represent all numbers and data; to perform all calculations using electronics rather than wheels, ratchets, or mechanical switches; and to organize a system in which computation and memory are separated. The system also pioneered the use of regenerative capacitor memory.

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For more moments in tech history, see this blog. EDN strives to be historically accurate with these postings. Should you see an error, please notify us.

Editor's note: This article was updated to correct spelling errors on October 18, 2013 and again on October 19, 2016.

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