The Man Who Invented the Computer by Jane Smiley (Hardcover)
The biography of John Atanasoff, Digital Pioneer.
One night in the late 1930s, in a bar on the Illinois–Iowa border, John Vincent Atanasoff, a professor of physics at Iowa State University, after a frustrating day performing tedious mathematical calculations in his lab, hit on the idea that the binary number system and electronic switches, combined with an array of capacitors on a moving drum to serve as memory, could yield a computing machine that would make his life and the lives of other similarly burdened scientists easier. Then he went back and built the machine. It worked. The whole world changed.