Atanasoff-Berry Computer

Atanasoff-Berry Computer (ABC) (reconstruction)

Engineers at Iowa State University built this working reconstruction of the Atanasoff-Berry Computer between 1994 and 1997. It is slightly smaller than the original, which was too wide to fit through a standard door— one reason why the original was not preserved.

Atanasoff-Berry Computer

Mathematician and physicist John Atanasoff, looking for ways to solve equations automatically, took a drive to clear his thoughts in 1937. At a Mississippi River roadhouse he jotted on a napkin the basic features of an electronic computing machine.

Atanasoff’s linear equation-solver, built with graduate student Clifford Berry, could solve a variety of problems but was not programmable.

John Vincent Atanasoff (1903-1995)

The need to solve physics problems numerically inspired associate professor Atanasoff to design the ABC. Atanasoff was awarded the National Medal of Technology in 1990.

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Close-up of the ABC

This shows the card reader and binary punch used for intermediate results, and a memory drum with its cover removed. Each drum stored 30 numbers.

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Clifford Berry (1918-1963)

Encouraged by his father, Berry tinkered with electricity as a child and became a brilliant student. Berry and Atanasoff both left Iowa in 1942 for defense-related jobs.

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Atanasoff-Berry add-subtract module (reconstruction)

The ABC used 30 add-subtract circuits for solving equations. When this reconstruction was built, it was found that the resistors had to be hand-selected to work correctly.

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ENIAC: The First Electronic Computer. Until it Wasn’t.

Being the first electronic computer involved more than bragging rights. It involved money.

ENIAC’s inventors filed for patents in 1947. They were finally issued in 1964, and patent-holder Sperry Rand sought royalties from competitors.

Honeywell and CDC objected, citing prior work by John Atanasoff, who conceived an electronic computer in 1937 and built it in 1939-1942. Significantly, ENIAC inventor John Mauchly had visited Atanasoff in 1941.

In 1967 the dispute landed in court. The ruling, recognizing Atanasoff’s earlier work, revoked Sperry’s patents. So, one of history’s key inventions is owned by…nobody.

United States Patent 3,120,606 (ENIAC)

The ENIAC patents triggered a lawsuit that spotlighted the ABC. The judge decided Mauchly derived ideas from Atanasoff. Computer architect Gordon Bell refers to the judgment, which invalidated the ENIAC patent, as the “disinvention” of the computer.

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John Vincent Atanasoff lecturing at the Computer Museum in Boston

A memory drum from the original ABC is in the foreground. The demonstration version of the ABC used for the lawsuit is in the background.

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