IBM PC Model 5150 with printer, 1981.

UNITED KINGDOM - APRIL 04: The IBM Personal Computer System was introduced to the market in early 1981, at a time when IBM was the world's largest mainframe computer manufacturer. Such was IBM's reputation that 200,000 of the PCs were sold in the first year. As a result it set a standard by which every other computer company was to be measured. The microcomputer market had grown from its beginnings in the kit building hobby market to a potential billion-dollar industry. The IBM PC used the Intel 8088 microprocessor, a factor which was also pivotal to Intel's growing success. The machine used magnetic tape to load data, and featured an optional floppy disk drive. The hard drive did not make an appearance until the release of IBM's XT machine in 1983. (Photo by SSPL/Getty Images)