ENIAC Unveiled

ENIACThe Electronic Numerical Integrator and Computer (ENIAC) was designed during World War II by J. Presper Eckert and John Mauchly at the University of Pennsylvania for the United States Army. It was the forerunner of Eckert and Mauchly’s UNIVAC, which was the first widely-available commercial computer. Because of the war, the University of Pennsylvania’s Moore School of Engineering had a contract with the United States Army to design an advanced machine that could perform military-related calculations, such as cannon trajectories. The machine, which came to be called ENIAC, was needed quickly, and the design team decided to use available materials and technology, such as vacuum tube processors and punched cards to store the program and data.

In 1941 when the project began, John Mauchly was a physicist who had recently joined the faculty and Presper Eckert was an engineering student. Also on the team was Arthur Burks, a mathematician and logic expert who was responsible for ENIAC’s circuitry. ENIAC contained 18,000 vacuum tubes and required 160,000 watts of power. It weighed thirty tons, and took up over 1,500 square feet. Using ten-digit decimal numbers, it could perform 5,000 additions or subtractions per second. It also multiplied, divided, and calculated square roots. Programming was originally provided by interconnected wiring, like a telephone switchboard. Later, it was refitted to use punched card programs.

The computer was dedicated in February 1946, and was used to compute the trajectories of artillery shells for the Army, Navy, and Air Force. It also performed calculations related to meteorology and to nuclear weapons research, including various radiation studies. ENIAC continued to operate until 1955. During its lifetime it demonstrated that electronic systems could be reliable as well as accurate, paving the way for future computers. But its design became the center of a legal controversy. In 1937, John Atanasoff, a physicist at Iowa State College  designed a computer with vacuum tube processors, binary numbers, serial calculation, punched cards for input and output, and memory consisting of condensers placing charges on rotating drums of Bakelite — a type of early plastic. Under Atanasoff’s faculty contract, the patent on anything that he invented would be held by the school — a common practice. However, when he asked Iowa State to patent his computer, the school refused.

By 1942, Atanasoff and Clifford Berry, a graduate student, built enough of the A-B-C computer — named for their initials — to calculate differential equations. Atanasoff then took up other World War II-related research and did not go back to the computer project. However, in December 1940, Atanasoff had met John Mauchly at a scientific meeting and invited him to Iowa to see the computer. The visit took place in June, 1941. Atanasoff demonstrated the A-B-C. Mauchly (who already had computer design experience) and Eckert went on to design and build ENIAC and to take out a patent on it. The ENIAC patent served as the basis for their later computers, EDVAC, BINAC, and UNIVAC, built by their own firm.

In 1950, Remington Rand bought their company, including all UNIVAC-related patents. By the 1960s, Remington Rand had become Sperry Rand. During that time a competitor, Honeywell, contacted Atanasoff and they decided to challenge the Sperry Rand patent. In court, Atanasoff’s case was based on his original design and on Mauchly’s visit to Iowa. Atanasoff’s machine was strictly a differential analyzer, and Mauchly countered that he had not stolen Atanasoff’s design. He contended that he had the main elements of his computer design before meeting with Atanasoff and seeing the A-B-C. Mauchly believed the design was flawed, though he was impressed with the performance, and he intended to build a general-purpose machine. Several scientists who had worked on ENIAC supported Atanasoff, while others supported Eckert and Mauchly. In 1973, the judge ruled in Atanasoff’s favor, declaring the ENIAC-UNIVAC patent invalid.

“ENIAC.” World of Invention. Gale, 2006. Science in Context. Web.


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