The Atanasoff-Berry Computer (ABC) was the world’s first electronic digital computer. John Vincent Atanasoff, a former Iowa State professor of physics and mathematics, and Clifford Berry, a former physics graduate student and electrical engineering undergraduate, built the computer at Iowa State University from 1937 to 1942.

Clifford Berry with Atanasoff-Berry Computer (Photo courtesy Iowa State University Library/Special Collections Department

In the project’s proposal, Atanasoff had planned to hire an electrical engineering student to assist him in building the computer. He then met an electrical engineering professor, Harold W. Anderson, while walking across campus. Atanasoff told Anderson the type of student he wanted and Anderson replied, “I have your man: Clifford Berry.”

The ABC looked nothing like today’s computers: It was the size of a big desk, weighed 750 pounds, and featured rotating drums for memory, glowing vacuum tubes, and a read/write system that recorded numbers by scorching marks on cards.

But, the machine also was the first to use several innovations that are still a part of today’s computers: a binary system of arithmetic, separate memory and computing functions, regenerative memory, parallel processing, electronic amplifiers as on-off switches, circuits for logical addition and subtraction, clocked control of electronic operations, and a modular design.

The Controversy of the ABC

The ABC’s place in computer history has been the subject of debate and even a federal court case.

When World War II interrupted work on the ABC, Atanasoff and Berry moved on to other jobs and projects. J. Presper Eckert and John Mauchly, developers of the ENIAC machine at the University of Pennsylvania, were the first to patent an electronic digital computer.

In 1973, however, U.S. District Judge Earl R. Larson overturned the ENIAC patents, writing, “Eckert and Mauchly did not themselves first invent the automatic electronic digital computer, but instead derived that subject matter from one Dr. John Vincent Atanasoff.” (Read more about the case from an electrical engineering alumnus, turned patent attorney, who investigated the patent.)

President George Bush awarded Atanasoff the National Medal of Technology on November 13, 1990.

Atanasoff died in 1995. Berry died in 1963, before the patent controversy over the ABC began.

History of Computing