Meanwhile, Eckert and Mauchly had left the Moore School and established a company to push computing into the realm of commerce. The product they envisioned, a 5,000-tube machine called UNIVAC, had a breakthrough feature—storing data on magnetic tape rather than by such unwieldy methods as punched cards. Although a few corporate customers were lined up in advance, development costs ran so high that the two men had to sell their company to the big office equipment maker Remington Rand. Their design proved a marketplace winner, however. Completed in 1951, UNIVAC was rugged, reliable, and able to perform almost 2,000 calculations per second. Its powers were put to a highly public test during the 1952 presidential election, when CBS gave UNIVAC the job of forecasting the outcome from partial voting returns. Early in the evening the computer (represented by a fake bank of blinking lights in the CBS studio) projected a landslide victory by Dwight Eisenhower over Adlai Stevenson. The prediction was made in such unequivocal terms that UNIVAC's operators grew nervous and altered the program to produce a closer result. They later confessed that the initial projection of electoral votes had been right on the mark.

By then several dozen other companies had jumped into the field. The most formidable was International Business Machines (IBM), a leading supplier of office equipment since early in the century. With its deep knowledge of corporate needs and its peerless sales force, IBM soon eclipsed all rivals. Other computer makers often expected customers to write their own applications programs, but IBM was happy to supply software for invoicing, payroll, production forecasts, and other standard corporate tasks. In time the company created extensive suites of software for such business sectors as banking, retailing, and insurance. Most competitors lacked the resources and revenue to keep pace.

Some of the computer projects taken on by IBM were gargantuan in scope. During the 1950s the company had as many as 8,000 employees laboring to computerize the U.S. air defense system. The project, known as SAGE and based on developmental work done at MIT's Lincoln Laboratory, called for a network of 23 powerful computers to process radar information from ships, planes, and ground stations while also analyzing weather, tracking weapons availability, and monitoring a variety of other matters. Each computer had 49,000 tubes and weighed 240 tons—the biggest ever built.