September 1996. I was lost in place at Iowa State University. I spent my afternoons generally avoiding people: wandering through every building on campus, seeing what was there and what sort of interesting things people were up to.

One day, I wandered into the campus computer center, and inside of a glass case was a small machine that looked like an overly complicated mechanical cash register. I walked over to the copper-colored device, looked it over for a while, and read the plaque below it.

It was the only functioning replica of the original Atanasoff-Berry computer. I had no idea what that device was; I was a biology major who dreamed of becoming a park ranger and had vague dreams of a Walden-like future for myself.

By the end of it all, I wound up with a degree in computer science.

The Atanasoff-Berry Computer
The First Electronic Digital Computer

The Atanasoff-Berry Computer, or ABC for short, was the first electronic digital computer. It was constructed over five years (1937-1942) on the campus of Iowa State University. This computer introduced such concepts as binary arithmetic, regenerative memory, logical circuits, and programmable computation. The concepts that went into the ABC were later used on the better-known ENIAC in the late 1940s.

Telling the story of the Atanasoff-Berry Computer begins with its creators, John Atanasoff and Clifford Berry.

John Vincent Atanasoff

John Vincent Atanasoff (b: October 4, 1903; d: June 15, 1995) was born into a New York household almost custom-built for someone to develop into a great electrical engineer: his father held that trade, and his mother was a mathematics teacher. He had an early interest in both electricity and mathematics: he rewired the back porch of his home at age nine, and at about that same age, became infatuated with a slide rule given to him by his father.

He excelled in school and by 1921 was a student at the University of Florida, earning a BS in electrical engineering with a perfect "A" average in 1925. After this, he received many offers for teaching fellowships, but he chose to accept one at Iowa State College because of Iowa State's strong reputation in engineering.

By 1930, Atanasoff had received his master's in mathematics, was married, and was working on his Ph.D. thesis on the dielectric constant of helium. While writing his thesis, Atanasoff needed to make many thousands of calculations, and thus he spent many days seated in front of a Monroe manual calculator, a very complicated machine that operated by hand crank, but was able to perform very complex calculations. To a born engineer like Atanasoff, such an inefficient device begged improvement, and thus after he received his Ph.D. in theoretical physics, he joined the Iowa State faculty as an assistant professor in mathematics and physics, with the goal of developing such a device.

Clifford E. Berry

Clifford Berry (b: April 19, 1918; d: October 30, 1963) was also born into a family that would harbor his interests in electricity; his father Fred was the owner of an electrical appliance store in Gladbrook, Iowa. When Clifford was four, Fred assembled a radio for display in his store, the first radio in Gladbrook. People would often visit the store just to hear the miracle of it, and Clifford was deeply curious. His father instructed him on how to assemble such radios, and before long, Clifford was able to assemble his own, eventually building his own HAM radio at age eleven.

Clifford's dream was to study electrical engineering at Iowa State College, so when Clifford became old enough, his entire family moved to Ames, Iowa so that Clifford could attend without leaving his family behind. He entered Iowa State College in the fall of 1935 and earned his BS in electrical engineering in 1939 with a very strong academic reputation.

At this point, a bit of luck took over. One of Berry's professors, Harold Anderson, was asked by his friend John Atanasoff if he could recommend a strong graduate student in electrical engineering to assist with his computer project. Anderson recommended Berry, and so in the spring of 1939, Atanasoff and Berry met for the first time.

Building The ABC

Atanasoff had been working on a computer prototype since 1937 and had progressed far enough to make a very simple prototype, which demonstrated the basic concepts of binary mathematics and logical circuits to process them, but this original prototype did not have the power to do any interesting computations by the spring of 1939. However, this prototype was impressive enough to earn Atanasoff a $650 grant to continue work on the project, which he used to hire a graduate student assistant, Clifford Berry.

Most of the work proper on the ABC occurred in the late spring, summer, and fall of 1939. However, in September 1939, the war was starting, and this would come to have a great impact on the development. Atanasoff went on leave that month to join a defense position at the Naval Ordnance Laboratory in Washington, D.C., as the nation quietly began to gear up for the second world war.

Berry remained in Ames, working furiously on the project, and was able to present a much more complete prototype to the Iowa State College Research Council in December 1939. This version was able to solve a small set of equations entirely through digital input, and so thoroughly impressed the council that Berry received another grant, this time of $850, to work with the remote Atanasoff on continuing the progress on the computer.

By mid-1940, the two men had written a paper entitled "Computing Machines for the Solution of Large Systems of Linear Algebraic Equations" and had submitted it to a patent lawyer for advice on how to protect their innovations. During 1940 and 1941, Berry continued progress on the machine, but spent the majority of his time focused on his class work, culminating in a masters degree in physics in 1941.

Abandoning The ABC

But the war was about to intervene again. On December 7, 1941, the Japanese bombed Pearl Harbor, and with that, Berry took a defense-related job in Pasadena, California. At this point, the Atanasoff-Berry Computer was capable of solving systems of linear equations, and it resided in the basement of Physics Hall on the campus of Iowa State College.

The ABC was largely abandoned at this point. Atanasoff and Berry both had jobs with the defense effort, and the machine sat in the basement of Physics Hall. Berry continued to work in absentia on his Ph.D. in physics, earning his degree in 1948.

In 1948, Atanasoff returned to Iowa State on a visit, only to discover that the machine had been disassembled to free up space in the basement of Physics Hall; all that remained of the ABC were some spare parts in a box.

Both men went on to have lengthy careers in the defense industry. Atanasoff remained with the Navy until late 1951, after which he went on to form The Ordnance Engineering Corporation, which was later purchased by Aerojet General; he retired in 1961. Berry worked at various defense industry positions until his untimely death in 1963.

Why Did My Teacher Tell Me The ENIAC Was The First Computer?

The ENIAC was developed in the late 1940s by John W. Mauchy, an old acquaintance of Atanasoff, and several major components of the ENIAC were patented by Mauchy. As a result of these patents, Mauchy was seen throughout the 1950s and 1960s as the creator of the computer and ENIAC was promoted widely as the first computer. These patents were held by the RAND Corporation and were upheld a number of times in the 1960s.

However, in 1971, Honeywell challenged these patents, and produced a great deal of documentation demonstrating that in June 1941, Mauchy had met extensively with Atanasoff and Berry and had been given full details and information on the Atanasoff-Berry computer. Among the patents taken out by Mauchy on the ENIAC include the use of logical circuits, regenerative memory, and the use of binary mathematics, all of which originated in the ABC.

On October 19, 1973, US District Court judge Earl Lawson handed down a judgement which struck down all of Mauchy's patents and stated unequivocally that the ideas for the ENIAC and the computer in general were "derived from Atanasoff, and the invention claimed in ENIAC was derived from Atanasoff."

Thus, the story of the ENIAC being the first computer is the result of a falsely filed and promoted patent from the late 1940s, which was overturned in 1973.

Technical Information

The ABC looked nothing like a modern computer, nor does it even look anything like the traditional idea of the 1950's computer. Instead, it looked something like a workbench, with a large array of individual components below, many of them featuring knobs so they could be pulled in and out. The top of the machine featured a card reader, which enabled the machine to accept cards punched with holes representing sequences of binary numbers.

The memory was in the form of a large drum, about six inches in length and with a radius of about two inches. These drums were capable of storing thirty numbers each, with each number being composed of fifty bits. This enabled the machine to hold numbers of 2 to the 50th power in size, or longer if concatenation of different number storages was used in the program. The drums were composed of a huge array of capacitors, with each one capable of storing a 1 or a 0. In essence, this is exactly how memory works today, only much, much smaller.

The components themselves were essentially small circuits designed to perform a specific task, such as adding two binary numbers or subtracting them. The programs, fed in by the punch cards, were in essence long series of tasks, usually just massive repetitions of feeding numbers through the add and subtract modules. This enabled cards to be re-used in lots of programs for more complicated tasks, much like a function in modern computer programming.

The ABC also had a device that could punch a card for output, giving the resulting number from your program on a punch card.

The modern computer is essentially just incremental steps from the original ABC, enabling us to do more and more complicated tasks. At its heart, though, every computer today is just an adder and subtracter running on electricity, just like the ABC, built in the middle of Iowa in the 1930s.


Atanasoff: Forgotten Father of the Computer. Clark R. Mollenhoff. 1988. Iowa State University Press. ISBN: 0813800323.

The First Electronic Computer : The Atanasoff Story. Alice R. Burks and Arthur W. Burks. 1988. University of Michigan Press. ISBN: 0472100904.

I acquired both of these books on the bargain table at the Iowa State University bookstore.

Log in or register to write something here or to contact authors.