Types of Mainframes.

You’ve learned that John Atanasoff built the Atanasoff-Berry Computer (ABC), the first electronic, digital computer. It was a special-purpose computer designed for a single task: solving simultaneous differential equations. But the ABC was also the basis for ENIAC, the world's first electronic, digital general-purpose computer.

Most mainframe computers are general-purpose machines. One of the earliest and most effective uses of general-purpose computers in business was the insurance industry's application of ENIAC's descendant, the UNIVAC computer system. The enormous amount of accounting required, together with the need to calculate complex actuarial tables for risks and premiums, gave the UNIVAC just the test it needed to prove its usefulness. It wasn't long before other large U.S. corporations were clamoring for their own computers.

Today, general-purpose mainframe computers play a major role in virtually every aspect of business and organizational life. IBM is largely responsible for this. IBM devised many accounting, calculating, and automatic tabulating machines and the first successful electric typewriter. But it was Tom Watson, Jr., who was mostly responsible for IBM's aggressive pursuit of the computer market. "By 1958, 1959," he said, "I realized that I had water in relatively large quantities and I had a dry sponge for a market. And if I could just learn to introduce that water into the sponge in acceptable form, there was no limit to where this business could go." In 1964, after investing four years and $5 billion, IBM introduced the System/360 mainframe computer, so named because a perfect circle has 360 degrees. It became the most popular mainframe in computer history and the standard for the industry.