The Atanasoff – Berry Computer ( ABC ) was the first electronic digital computing device.

However, its intermediate result storage mechanism, a paper card writer / reader, was unreliable, and when inventor John Vincent Atanasoff left Iowa State College for World War II assignments, work on the machine was discontinued.

Atanasoff and Clifford Berry's computer work was not widely known until it was rediscovered in the 1960s, amidst conflicting claims about the first instance of an electronic computer.

At that time, the ENIAC was considered to be the first computer in the modern sense, but in 1973 a U. S. District Court invalidated the ENIAC patent and concluded that the ENIAC inventors had derived the subject matter of the electronic digital computer from Atanasoff ( see Patent dispute ).

The mechanical and logic design was worked out by Dr. Atanasoff over the next year.

The ABC was built by Dr. Atanasoff and graduate student Clifford Berry in the basement of the physics building at Iowa State College during 1939 – 42.

The memory of the Atanasoff – Berry Computer was a pair of drums, each containing 1600 capacitors that rotated on a common shaft once per second.

Although the Atanasoff – Berry Computer was an important step up from earlier calculating machines, it was not able to run entirely automatically through an entire problem.

This problem was not solved by the time Atanasoff left the university for war-related work.

The case was legally resolved on October 19, 1973 when U. S. District Judge Earl R. Larson held the ENIAC patent invalid, ruling that the ENIAC derived many basic ideas from the Atanasoff – Berry Computer.

In 1939, John Vincent Atanasoff and Clifford E. Berry of Iowa State University developed the Atanasoff – Berry Computer ( ABC ), The Atanasoff-Berry Computer was the world's first electronic digital computer.

However, upon seeing how bad the footage of the video was, Perry threw up, Larriva threatened to quit, and Atanasoff was not seen around for days.

* The American Atanasoff – Berry Computer ( ABC ) ( shown working in summer 1941 ) was the first electronic computing device.

The ABC was dismantled by Iowa State University, after John Atanasoff was called to Washington, D. C. to do physics research for the U. S. Navy.

For a variety of reasons ( including Mauchly's June 1941 examination of the Atanasoff – Berry Computer, prototyped in 1939 by John Atanasoff and Clifford Berry ), US patent 3, 120, 606 for ENIAC, granted in 1964, was voided by the 1973 decision of the landmark federal court case Honeywell v. Sperry Rand, putting the invention of the electronic digital computer in the public domain and providing legal recognition to Atanasoff as the inventor of the first electronic digital computer.

The federal judge who presided over the case ruled that " the subject matter was derived " from the earlier Atanasoff – Berry Computer ( ABC ).

Letters he wrote to Atanasoff show that he was at one time at least considering building on Atanasoff's approach.

Atanasoff – Berry Computer replica at 1st floor of Durham Center, Iowa State University

In 1997, a team of researchers led by John Gustafson from Ames Laboratory ( located on the Iowa State campus ) finished building a working replica of the Atanasoff – Berry Computer at a cost of $ 350, 000.

Atanasoff – Berry Computer replica at 1st floor of Durham Center, Iowa State University

Atanasoff – Berry Computer replica at 1st floor of Durham Center, Iowa State University

* The Atanasoff-Berry computer is considered the first electronic digital computing device built by John Vincent Atanasoff and Clifford Berry at Iowa State University during 1937 – 1942.

Upon completion of his doctorate, Atanasoff accepted an assistant professorship at Iowa State College in mathematics and physics.

Atanasoff first met Mauchly at the December 1940 meeting of the American Association for the Advancement of Science in Philadelphia, where Mauchly was demonstrating his " harmonic analyzer ", an analog calculator for analysis of weather data.

( During the Philadelphia trip, Atanasoff and Berry also conducted a patent search at the Patent Office in Washington, D. C .)

Atanasoff died in 1995 of a stroke at his home after a lengthy illness.

* The Atanasoff Archives at Iowa State

* Atanasoff Personal Papers at Iowa State

* John V. Atanasoff Dies at Age 91 Invented First Electronic Computer – Washington Post Obituary, 1995

The CYCLONE, was an early computer built in 1959 by John Vincent Atanasoff and his assistant Clifford Berry at Iowa State College ( now Iowa State University ), was based on the Institute for Advanced Study ( IAS ) architecture developed by John von Neumann.

* Mollenhoff Papers at Iowa State U. on John Atanasoff

In the 1973 decision of Honeywell v. Sperry Rand, a federal judge named Atanasoff the inventor of the electronic digital computer.

Following the resolution of Honeywell v. Sperry Rand, Atanasoff was warmly honored by Iowa State College, which had since become Iowa State University, and more awards followed.

Mollenhoff's book gives the Atanasoff perspective of the 1973 federal court decision of Honeywell v. Sperry Rand that ruled the ENIAC computer patent invalid, and increased attention to Atanasoff's work.

According to Atanasoff's account, several key principles of the Atanasoff – Berry Computer were conceived in a sudden insight after a long nighttime drive during the winter of 1937 – 38.

Problems of this scale were becoming common in physics, the department in which John Atanasoff worked.

He submitted many of these problems to Atanasoff.

Judge Larson explicitly stated, " 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 ".

Machines such as the Z3, the Atanasoff – Berry Computer, the Colossus computers, and the ENIAC were built by hand using circuits containing relays or valves ( vacuum tubes ), and often used punched cards or punched paper tape for input and as the main ( non-volatile ) storage medium.

Between 1954 and 1973, Atanasoff was a witness in the legal actions brought by various parties to invalidate electronic computing patents issued to John Mauchly and J. Presper Eckert, which were owned by computer manufacturer Sperry Rand.

Atanasoff agreed to assist the attorney, but IBM ultimately entered a patent-sharing agreement with Sperry Rand, the owners of the Eckert-Mauchly memory patent, and the case was dropped.