U.S. physicist. He received his Ph.D. from the University of Wisconsin. With Clifford Berry, he developed the Atanasoff-Berry Computer (1937–42), a machine capable of solving differential equations using binary arithmetic. In 1941 he joined the Naval Ordnance Laboratory; he participated in the atomic bomb tests at Bikini Atoll (1946). In 1952 he established the Ordnance Engineering Co., which he later sold to Aerojet Engineering Corp. In 1973, after a judge voided a patent owned by Sperry Rand Corp. on ENIAC, the Atanasoff-Berry Computer was credited as the first electronic digital computer.