Computer History: All About the ENIAC

What Was the ENIAC?

The ENIAC, or Electronic Numerical Integrator and Computer, was the result of a U.S. government-funded project during World War II to build an electronic computer that could be programmed. The project was based out of the University of Pennsylvania's Moore School of Engineering. The design team included engineer J. Presper Eckert Jr. and physicist John Mauchly under the leadership of Herman Goldstine. The team began work on the project in 1943. John von Neumann, a noted mathematician of the day, began consulting on the project in 1944.

How Did the ENIAC Work?

Unlike the computers of the present day, the ENIAC was designed with one specific goal. It was programmed to compute the values of artillery range tables. Plugboards were used to relay instructions to the machine, which could then do the computations at high speed. This was a major time-saver compared to other computers of the era, which used punchcard readers or other mechanical devices that slowed the machines down. Unfortunately, the drawback to the plugboards was that each time the programmers wanted the computer to work on a new problem, it had to be shut down for days so that the wires plugged into the plugboard could be reconfigured.

Even with that drawback, the ENIAC was still the most powerful computer of its time. It is considered the first general electronic digital computer that was programmable. It was designed to use conditional branching; this means that like the Analytical Engine designed by Charles Babbage or the British computer Colossus (also built during World War II), it could be given instructions to take different actions depending on the value of one data point. This made ENIAC a flexible machine. Even though it was designed to calculate artillery range tables, it was possible to reprogram the machine for many other uses.

Facts and Figures About the ENIAC

The ENIAC was a huge machine, taking up a 1,500-square-foot room at the Moore School. The machine was made up of 40 panels arranged in a U-shape along three of the room's walls. Along with the panels, which were each 8 feet high, 2 feet wide, and 2 feet deep, the machine included 70,000 resistors, 17,000 vacuum tubes, 10,000 capacitors, 1,500 relays, and 6,000 switches. ENIAC ran constantly to extend the life of its vacuum tubes, and it generated large amounts of heat. The room had to have its own air conditioning system to keep the computer from overheating.

The machine was completed in February 1946 at a total cost of about $400,000. Its purpose was to help the United States win World War II, but the war ended before the machine was finished. Instead, its first job was doing calculations to help with building hydrogen bombs.

Additional Information

• Programming the ENIAC: The women involved in programming the ENIAC, the computer's place in history, and original photographs from the design process are included in this article produced by Columbia University.
• Celebrating Penn Engineering History: ENIAC: The University of Pennsylvania discusses its own place in the history of the ENIAC and the machine's contributions to the history of computers.
• ENIAC Programmers Project: Six women programmed the ENIAC, but their contributions to the field of computer science were largely ignored for many years. This project explores their lives and scientific contributions.
• Untold History of AI: Invisible Women Programmed America's First Electronic Computer: Women often worked doing computations at the dawn of the computer age, although their contributions were often not considered as important as those of the men they worked alongside.
• ENIAC Accumulator #2: Part of the machine now resides at the Smithsonian in Washington, D.C.
• The Brief History of the ENIAC Computer: Smithsonian Magazine reflects on the computer that took up an entire room and sparked a digital revolution.
• The Scientific and Technological Advances of World War II: War often brings about advances in technology as governments fund projects that they think will increase their chances of winning. These advances often trickle down to impact civilian life.
• Colossus: Birth of the Digital Computer: While the Americans worked on the ENIAC, the British funded and built the Colossus to aid them in the war effort.
• John Presper Eckert: Read a biography of the lead engineer in charge of designing the ENIAC, including details about his lifelong ties to Pennsylvania.
• John Mauchly: The American Institute of Physics transcribed an oral interview given by Mauchly that includes details on his work on the ENIAC project.
• Herman Heine Goldstine: Goldstine was educated at the University of Chicago and was part of the Army when he was assigned to oversee the building of the ENIAC.
• John von Neumann: Von Neumann became a United States citizen in the late 1930s. During World War II, he consulted on the ENIAC, but he was also a vital part of the Manhattan Project.
• Definition of a Plugboard: PC Magazine describes exactly what a plugboard is and how it functioned.
• John Ambrose Fleming Invents the Vacuum Tube, Beginning Electronics: The development of digital computers, including the ENIAC, was enabled by the invention of the vacuum tube.
• Charles Babbage: The BBC wrote this biography of the famous mathematician and pioneering figure in the field of computer science.
• The Engines: The machines that Charles Babbage invented, including his Analytical Engine, are described and pictured in this article by the Computer History Museum.