Home TECHNOLOGY Atanasoft-Berry Computer (ABC) by John Vincent Atanasoff and Clifford Berry

Atanasoft-Berry Computer (ABC) by John Vincent Atanasoff and Clifford Berry

Atanasoff–Berry computer replica at Durham Center, Iowa State University

The Atanasoff–Berry computer (ABC) was the first automatic electronic digital computer. Limited by the technology of the day, and execution, the device has remained somewhat obscure. The ABC’s priority is debated among historians of computer technology, because it was neither programmable, nor Turing-complete, unlike the widely famous ENIAC machine of 1947 in part derived from it.

The Atanasoff-Berry Computer (ABC) occupies a special place in the history of computing in part for its technical accomplishments but also for being at the center of a landmark legal case. It was built by Iowa physics professor John Vincent Atanasoff and graduate student Clifford Berry. Technically, the ABC was an electronic equation solver. It could find solutions to systems of simultaneous linear equations with up to 29 unknowns, a type of problem encountered in Atansasoff’s physics work. Construction of the ABC began in 1938 at Iowa State College (now University) in Ames, Iowa.

It was about the size of a large desk, weighed 750 lbs, computed 0.06 operations per second (sustained) and had 0.37 KB of memory. It could also do 30 add/subtract operations per second.

While not a computer in the modern sense (since it did not store its own program), it pioneered various techniques in digital computer design including binary arithmetic, parallel processing, and electronic (vacuum tube) switching elements.

The device was completed in 1942 and worked, although its spark-gap printer mechanism needed further development. The legal dimension to the ABC story involves a lawsuit between two computer makers, Honeywell and Sperry-Rand.

In 1967, Honeywell sued Sperry over their ENIAC patents using the ABC as evidence of prior art. (ENIAC was an early digital electronic calculator completed in 1946). After years of proceedings, on October 19, 1973 the judge in the case, Earl R. Larson, agreed with Honeywell that some of the ideas in the ENIAC, which had been considered the ‘world’s first computer,’ in fact came from Atanasoff during a four-day visit ENIAC designer John Mauchly made to Atanasoff at Iowa State before ENIAC was designed.

There was also months of correspondence between the two in which Mauchly expressed his desire to build a similar device. The net result of this judgment was that no one owned the patent on the computer: it was free to be developed by all. Gordon Bell has called this the ‘dis-invention of the computer.’ In 1993, Iowa State University began a historically-accurate reconstruction of the ABC, which it finished in 1997. The project cost $360,000 and involved about a dozen people in its realization.

This film shows the ABC Reconstruction in operation, solving a simple algebra problem.

Catalog number: 102781093 Lot number: X6054.2011  [Recorded: 1999]

Computer History Museum

The Forces That Led to the Atanasoff-Berry Electronic Computer, lecture by John Atanasoff

Recorded: November 11, 1980; b/w

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.

Why don’t we know the name of John Atanasoff as well as we know those of Alan Turing and John von Neumann? Atanasoff never secured a patent for his early device, and a number of the concepts he pioneered were incorporated into the breakthrough ENIAC computer that evolved into the legendary UNIVAC. But in 1973 a court declared that the patent on the Sperry Rand UNIVAC device was invalid, opening the intellectual property gates to the computer revolution.

In 1980, Dr. John Atanasoff gave a lecture at the Digital Computer Museum in Massachusetts (a forerunner of the Computer History Museum). In this lecture (introduced by Gordon Bell) Dr. Atanasoff discusses his life, the events that lead to his breakthroughs in computing and the design of the Atanasoff–Berry Computer.

Lot Number: X6118.2011
Catalog Number: 102694989

Computer History Museum



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