John Atanasoff (1903–1995) and Clifford Berry (1918–1963) built the world’s first electronic digital computer at Iowa State College between 1939 and 1942. Atanasoff, a physics professor, provided the “epiphany” that binary logic and vacuum tubes were the future of calculation.
Berry, his graduate student, turned that theory into the ABC (Atanasoff-Berry Computer). They pioneered “regenerative memory” and the separation of memory from the processing unit. Their machine was never fully perfected but a working replica built in 1997 proved the theory.