What Was ENIAC?

Mary McMahon

The Electronic Numerical Integrator and Computer (ENIAC) was the first electronic digital computer, completed in 1946 for the United States military. It was used to compute information for a variety of military tasks until 1955, when it was retired in favor of other, more advanced devices. ENIAC is regarded as one of the forefathers of the modern personal computer, and represents a huge engineering and mathematics accomplishment. Pieces of ENIAC can be seen on display in various museums all over the United States.

Man holding computer
Man holding computer

In 1943, the military awarded a contract to John Mauchly and J. Presper Eckert of the University of Pennsylvania. The two were contracted to build a device which could be used to calculate artillery tables for the military. After three years of work, the end product was revealed on 14 February 1946. Although it was initially designed to work on artillery tables, ENIAC's first major project was calculations related to the development of the hydrogen bomb.

The first iteration of ENIAC was a far cry from modern computers. It ran on a decimal, rather than a binary, system and took up 1,800 square feet (167 square meters) of floorspace with 42 separate panels. The intense heat generated by ENIAC required it to be run in a climate controlled room, and the vacuum tubes failed rather frequently. It had to be manually set when a program needed to be run, and it had no stored memory. Input and output were achieved through punch cards.

Although ENIAC may seem primitive to modern computer users, it was a substantial achievement. The history of the people who worked on ENIAC also demonstrates the egalitarian nature of the computer engineering field. Women worked side by side with men, and were primarily responsible for the daily running of ENIAC. Female programmers also developed improvements to ENIAC, and were honored in 1997 by the Women in Technology Hall of Fame. During an era when many women struggled for equal positions in the work place, the hard working ENIAC crew was an anomaly.

Reforms and improvements continued to be made to ENIAC until it was finally retired. Many of these reforms played a role in the development of later computers, such as internal memory and the use of binary representation rather than decimals. While the processing power of a modern computer is enclosed in a much small space than the room-sized ENIAC, it deserves an important place in history for the computer engineering which it inspired.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a EasyTechJunkie researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


@everetra - Here’s another computer to throw into the mix: UNIVAC. You guys seemed to have forgotten this bad boy, but this was the first real commercial computer, without question. Those other models were built for military purposes.

UNIVAC was built by the same guys who built ENIAC and it was sold in the early 1950s, first to the Census Bureau and other government agencies and then eventually to life insurance companies. I think UNIVAC was the real first computer. That’s my take.


@NathanG - I actually think the EDVAC computer is the real precursor to the modern computer. Yes, I was taught this too but I think it has some merit beyond marketing. The reason is that the EDVAC computer used the binary numbering system whereas the ENIAC used decimal, and EDVAC had its own stored memory.

It was small memory by modern standards, but it was still memory. It also used magnetic tape to store programs. Those are the reasons that I think EDVAC was the real McCoy when it comes to answering the question of when was the computer invented.


@miriam98 - I’ve heard that, too. Anywhere you get into a discussion about the history of computers you will get some people who will want to set the record straight about ENIAC facts vs myths.

However, in the final analysis, I don’t think it matters because ENIAC was the largest of its kind and it worked better than other models. In my opinion inventions are always like this, even in the modern era.

You ask, for example, who invented Windows? Was it Bill Gates or was it Apple or Xerox, from which Gates allegedly stole his idea? I think marketing has a big role in defining the real facts of our history for consumer products.


In college I was taught that there was some debate about whether the ENIAC computer was in fact the first computer. There were other computers during that wartime period that performed similar functions but they never caught the spotlight. I think they were meant to be kept secret because of the nature of their work.

Some were being built in other universities like Harvard, and even in the late 1930s there was another computer that was built to solve linear algebraic equations. I don’t think it was anywhere near as big as ENIAC and was never completed.

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