ENIAC Accumulator #2

ENIAC was built by a team of engineers at the Moore School at the University of Pennsylvania between May 1943 and February, 1946. The team was working under contract for the Ballistics Research Laboratory of the U.S. Army Ordnance Department. The name ENIAC is an acronym of Electronic Numerical Integrator and Computer. Principal engineers on the project were J. Presper Eckert and John W. Mauchly. When complete, ENIAC filled a room measuring 30 feet by 50 feet and weighed 30 tons. It used around 18,000 vacuum tubes of 16 types, 1500 relays, 70,000 resistors, and 10,000 capacitors. It was 8 feet high, 3 feet wide, almost 100 feet long (if stretched out), and consumed 140 kilowatts of power. Construction costs were around half a million dollars.
The Army commissioned ENIAC to perform a specific function: computing ballistics tables for aiming Army artillery. Creating accurate tables was a laborious process of solving differential equations for hundreds of positions and configurations for each gun. When the ENIAC project was started, human "computers" (largely women) were performing the calculations by hand with mechanical calculators, and they were falling hopelessly behind schedule. If the operations could be done in a pre-programmed sequence by an electronic machine, not only would they be completed faster, but results should include fewer errors than hand calculation.
By the time ENIAC was finished, the war was over, and the original goal was no longer a pressing matter. All along, however, the development team realized that what they were creating in ENIAC was much more than a special purpose calculating device.
An Army press release announcing its creation in 1946 proclaimed boldly: "A new machine that is expected to revolutionize the mathematics of engineering and change many of our industrial design methods was announced today by the War Department…. This machine is the first all-electronic general purpose computer ever developed. It is capable of solving many technical and scientific problems so complex and difficult that all previous methods of solution were considered impractical…. Begun in 1943 at the request of the Ordnance Department to break a mathematical bottleneck in ballistic research, its peacetime uses extend to all branches of scientific and engineering work."
The claim, voiced here, that ENIAC was the "first all-electronic general purpose computer…" has been a source of controversy ever since. Much of the debate has centered on patent issues. To summarize a complicated story, Eckert and Mauchly belatedly filed a patent application based on ENIAC in June 1947. They finally received a patent in 1964. The claims in their patent were broad, and soon Sperry Rand, the company with which Eckert and Mauchly were working by this time, began seeking infringement fees. Sperry Rand settled privately with IBM, but another target, Honeywell, challenged the patent. After a detailed investigation and trial, Judge Earl Lawson invalidated the ENIAC patent in late 1972. In part he ruled that crucial elements of ENIAC derived from prior work by John V. Atanasoff, an inventor who had built a special-purpose electronic computer at Iowa State College in the late 1930's. Although Atanasoff machine never worked well and he ultimately dropped the project, John Mauchly had known and visited him, and arguably got some ideas from this connection.
The ruling by Judge Lawson has been taken by some to be proof that Atanasoff was the "Father of the Computer" and that Eckert and Mauchly were of subsidiary importance.
Most computer historians claim, however, as Mauchly himself did, that if he and Eckert got anything from Atanasoff's work, its significance was of limited importance to the success of the project. In large part, this is because the genius of ENIAC derived more from the brilliance of its engineering than its fundamental conceptual design.
Like most important technologies, the electronic digital computer ultimately derived from many sources and the work of many people. Besides contributions made in the United States, important developments were also made in Europe before and during World War II. Many people in addition to those involved in the patent fight made important contributions to the evolution of the digital computer. These included pioneers such as George Stibitz at Bell Laboratories, Howard Aitken at Harvard University, Konrad Zuse in Germany, and others.
ENIAC remains singularly important, however, because it marks a major transition. It stood at the beginning of the digital computer industry in the United States. No machine before ENIAC was as large or powerful. None had its technical sophistication. Before it, no companies were striving to create and sell electronic digital computers as a principal line of business. ENIAC proved that a general-purpose electronic computer was both possible and valuable. After the War, and largely because of ENIAC, the field of digital computers was open. ENIAC was a clear, public announcement that the digital electronic computer had arrived, and that the Federal Government was strongly supporting its development.
Currently not on view
Object Name
mainframe component
Date made
University of Pennsylvania
Physical Description
metal (overall material)
overall: 102 in x 24 in x 24 in; 259.08 cm x 60.96 cm x 60.96 cm
Place Made
United States: Pennsylvania, Philadelphia
ID Number
catalog number
accession number
Computers & Business Machines
See more items in
Medicine and Science: Computers
Data Source
National Museum of American History, Kenneth E. Behring Center
Related Publication
Kendrick, Kathleen M. and Peter C. Liebhold. Smithsonian Treasures of American History
Additional Media

Visitor Comments

8/19/2016 1:55:16 PM
What was the Government project name for the ENIAC? All I read was what ENIAC stood for but did not know if that was the name the government gave the project.
10/12/2016 7:28:00 AM
Peggy Kidwell, NMAH
Proposers of the what came to be called the ENIAC initially called it an "electronic difference analyzer." This name was quickly superseded by ENIAC. A code name used for the ENIAC project was Project PX. However, staff at the Moore School of Electrical Engineering regularly filed "ENIAC" progress reports with the government. Thomas Haigh, Mark Priestley, and Crispin Rope discuss these matters in their recent book, ENIAC in Action.
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