ABC (Atanasoff-Berry Computer) 1940

The Atanasoff computer was approximately the size of a large desk. It had approximately 270 vacuum tubes. Two hundred and ten tubes controlled the arithmetic unit, 30 tubes controlled the card reader and card punch, and the remaining tubes helped maintain charges in the condensers.

The Atanasoff computer employed rotating drum memory. Each of the two drum memory units could hold about thirty fifty-bit numbers.

The computer operator's console contained a series of buttons, meters, lights and controls, mounted on top of the computer's metal frame. The Atanasoff machine was used to solve linear equations.

Dr. John V. Atanasoff had been interested in mechanizing the process of calculation since 1935. In 1939, he received a research grant of $650 to build a prototype of a computer he had designed for solving linear equations. Atanasoff, along with Clifford Berry, a graduate student, developed the first working prototype electronic digital computer. Before this time, computing devices had been either mechanical, electromechanical, or analog based.

The ABC computer, as it was later called, was the first electronic digital computer. Although it was a very significant technical achievement, the machine had a variety of limitations. It was slow, required constant operator monitoring, and was not programmable. In 1948, the original ABC computer was dismantled by Iowa State University officials, without the knowledge of Atanasoff. Only a few original components survived.

John Vincent Atanasoff


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