Fact Checked

What Was the First Digital Computer?

John Lister
John Lister

The identity of the first digital computer is a topic that has been debated, both in terms of the facts and in definition. The closest thing to an official answer is the Atanasoff-Berry Computer, or ABC, which was declared the first electronic digital computer in a 1973 court case. It was not a programmable computer, meaning it does not fall into the category of what most people would call a computer today.

To qualify as the first digital computer, a machine would have had to meet two definitions. A computer is a machine that can carry out a series of operations, either mathematical or logical. A digital computer is one that uses numerical values for its operations, usually through binary code that expresses all data through either a 0 or a 1. In contrast, an analog computer uses a physical property. Examples include a slide rule or a machine that uses the flow of water to simulate the flow of money in an economy.

The slide rule is a mechanical analog computer.
The slide rule is a mechanical analog computer.

From a legal perspective, two machines made a claim to be the first digital computer. One was Electronic Numerical Integrator And Computer, or ENIAC, which was built between 1943 and 1946. It was used to calculate the flight paths of projectile missiles for the United States Army.

The second claimant was the Atanasoff-Berry Computer, built between 1937 and 1942 at Iowa State College. It was not widely publicized, which led to a common belief that ENIAC had been first and allowed the creators of ENIAC to take out a patent. In 1973 this patent was deemed invalid by a US district court. This ruling officially noted the ABC as the first electronic digital computer.

Early electric analog computers used to take up entire rooms.
Early electric analog computers used to take up entire rooms.

It can be argued that the ABC was not a true computer, however. This is because it was not programmable, meaning it could only perform one set of functions, rather like a pocket calculator. The first known programmable computer was the Z3, produced by German engineer Konrad Zuse in 1941. This was arguably not a digital computer though; it used electromechanics in the form of magnetic switches.

The first digital computer that was fundamentally the same in concept as modern machines was the Manchester Small-Scale Experimental Machine, completed in Manchester, England, in 1948. It allowed users to input a new program, albeit in a very slow manner. The Manchester machine was purely an experiment to prove the concept. A year later the Electronic Delay Storage Automatic Calculator in Cambridge, England, became the first programmable computer used for commercial purposes.

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Discussion Comments


@Mammmood - I remember watching a TV show that talked about the question of what is a computer, and tried to answer the question, when was the first computer built?

Immediately I thought they were going to talk about Apple or Microsoft or IBM or something like that. To my surprise, they talked about this ancient analog computer, made up of gears and moving parts, which was supposed to simulate the motions of the planets around the sun.

I guess it depends on what you want to define as a computer; this thing had limited application to astronomy, but the TV host said that it had the sophistication of a Swiss watch, using the parts they had back then.

I think it’s remarkable to realize that mankind hasn’t changed that much. It’s just a matter of what resources we’ve had access to.


@hamje32 - I think it’s about more than marketing. Having the coveted “first ever” title means that you can leverage that label in a number of ways.

If I recall correctly, John Atanasoff got the National Medal of Honor for the ABC computer. I don’t think he would have gotten it if he were the inventor of the “second ever digital computer.”

No one remembers second place in anything, so I certainly can see why the folks who built the ABC computer thought it was worth a legal challenge.


I guess I don’t really understand why the issue of what was really the first electronic digital computer ever went to court, unless ENIAC used it in their marketing efforts.

These distinctions are somewhat irrelevant in my opinion. In college we were taught that it was ENIAC, but that the ABC computer was actually completed first but never got to market right away.

I think it proves that the real point is not who or what is the real claimant to any particular label, but who runs the best marketing campaign. Take the issue of Microsoft and Apple and even Xerox.

Did Microsoft really “invent” Windows or was it part of Apple before that or even Xerox, which had a similar implementation? You could take it to court, and argue that Microsoft is not the real originator of Windows, but it doesn’t matter. Microsoft won the marketing battle, and for all practical purposes, owns Windows.

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    • The slide rule is a mechanical analog computer.
      By: poselenov
      The slide rule is a mechanical analog computer.
    • Early electric analog computers used to take up entire rooms.
      By: NASA on The Commons
      Early electric analog computers used to take up entire rooms.