ENIAC, the University of Pennsylvania’s Electronic Numerical Integrator and Computer, was the world’s first wholly electronic digital computer.
Introduced to an eager public on February 15, 1946, the machine revolutionized computational science and
Radically advanced the speed by which mathematical equations could be solved. Problems that once would have taken months of simple hand calculations or days with the assistance of a differential analyzer now took only minutes. In the words of the New York Times’ first report on the machine, ENIAC promised “a new epoch of human thought.”
Computing machines were nothing new by the early 1940s. Humans have used one type, the abacus, for nearly
5.000 years, and many still use this elegant tool even today. In the 1930s, engineers at the Massachusetts Institute of Technology developed a “product integraph,” which solved simple equations through analog functioning. Later that decade, the International Business Machines corporation (IBM), with the aid of Harvard mathematicians, produced a sequence-controlled calculator capable of computing tables of mathematical functions such as sines and cosines. Unlike these early calculators, however, ENIAC was wholly electronic, functioning by turning vacuum tubes on and off. This was its great advance. It used no moving parts to perform its calculations, and it could thus function at astonishing speeds unhindered by the physical limitations of its predecessors. Its design proved capable of performing over
5.000 additions or subtractions or 360 multiplications of two 10-digit decimal numbers in a single second. No other machine on the planet could even approach these figures.
Such speed made complex problems appear simple, and the machine was designed with one specific problem in mind. In the early 1940s, America was at war against the Axis Powers, engaged in a conflict in which science and technology played a far greater role than ever before. In particular, America’s army required hundreds of complex ballistic tables for powerful artillery pieces, tables that listed the expected trajectory of shells through hundreds of trajectories. Each of these tables required thousands of computations and could take a trained mathematician using the most advanced tools of the time nearly a month to complete. Dozens of “human computers,” mainly young women with advanced mathematics degrees, were engaged in producing such tables at the University of Pennsylvania’s Moore School of Electrical Engineering, home to the world’s largest differential analyzer, but a faster method was needed. John W. Mauchly, a young professor, and John P. Eckert, Jr., a graduate student, proposed a machine that would use more than 18,000 vacuum tubes operating at a rate of 100,000 pulses per second to calculate the timeconsuming tables. Immersed in a desperate war, the army agreed to fund the project.
The top-secret machine took nearly two years to build. Completed in the war’s final year, Mauchly and Eckert’s 30-ton creation, housed in a good-sized room, appeared too late to be used for its original purpose of calculating ballistic tables. Instead, ENIAC’s first task dealt with calculations required for the construction of the atomic BOMB. Data was fed to ENIAC on punched cards, and the final results were themselves punched onto cards. Electronic circuits involving miles of wire performed the arithmetic computations, with such success that its operators eventually formed a waiting list of more than two years for eager users. Though a technological watershed, the machine was by no means perfect. Each new computation or program used a different wiring pattern, and thus shifting from one type of calculation to another required a manual rewiring of the machine that often took days—time that was in high demand for the world’s only functioning computer. This difficulty was overcome in 1948 by hard-wiring more than 80 operations into the machine, albeit at a loss of some operating speed. Hard-wired operations were controlled by ENIAC’s operator at a main console, and could be shifted—the machine in essence reprogrammed—at the flick of a switch, a technique that foreshadowed future computer designs.
As originally designed, ENIAC was also unable to store its data or results, even in the midst of its own computations. The machines’ creators had recognized the significance of this deficiency while in the midst of its construction, and began designing its successors, the EDVAC and the EDSAC, in 1944 even before ENIAC ran its first program. Data storage and stored programming would be the hallmarks of these new machines. Though a marvel of its day, ENIAC’s monopoly on electronic computing was, by necessity, short-lived. Its architecture and design were themselves never copied, and though the computer worked for many years at the university and at the U. S. Army’s Aberdeen Proving Ground in Maryland, its greatest contribution to the nascent field of computer science lay in its very existence. It proved rapid electronic machines both viable and useful, and it provided a testing ground for a whole generation of computer pioneers.
Further reading: Barkley W. Fritz, “ENIAC—A Problem Solver,” IEEE Annals of the History of Computing 16, no. 1 (1994): 25-40; Scott McCartney, ENIAC, the Triumphs and Tragedies of the World's First Computer (New York: Walker Press, 1999).
—Jeffrey A. Engel
World History
