Atanasoff-Berry Computer
(ABC) An early design for a binary calculator, one of the predecessors of the digital computer. The ABC was partially constructed between 1937 and 1942 by Dr. John Vincent Atanasoff and Clifford Berry at Iowa State College. As well as binary arithmetic, it incorporated regenerative memory, parallel processing, and separation of memory and computing functions.
The electronic parts were mounted on a rotating drum, making it hybrid electronic/electromechanical. It was designed to handle only a single type of mathematical problem and was not automated. The results of a single calculation cycle had to be retrieved by a human operator, and fed back into the machine with all new instructions, to perform complex operations. It lacked any serious form of logical control or conditional statements.
Atanasoff's patent application was denied because he never have a completed, working product. Ideas from the ABC were used in the design of ENIAC (1943-1946).