IBM PC compatible
IBM PC compatible refers to a class of computers which make up the vast majority of smaller computers (microcomputers) on the market today. They are based on the original IBM PC, use the Intel x86 architecture and are capabable of using interchangable commodity hardware.
The origins of this platform came with the decision by IBM in 1981 to market a personal computer as quickly as possible. In licensing an operating system from Microsoft, IBM's agreements allowed Microsoft to sell DOS for non-IBM platforms. Also, in creating the platform, IBM used only one proprietary component: the BIOS.
Compaq Computer Corporation manufactured the first non-IBM IBM PC compatible in 1984. Compaq could not directly copy the BIOS as a result of the court decision in Apple v. Franklin, but it could reverse-engineer the IBM BIOS and then write its own BIOS using clean room design.
Since 1984, IBM PC compatibles have conquered both the home and business markets of commodity computers so that the only notable remaining competition comes from Apple Macintosh computers with a market share of only a few per cent. Meanwhile, IBM has lost ground in the market for IBM PC compatibles; currently (as of 2003) major market players include Dell, HP, and IBM.
Despite advances in computer technology, all current IBM PC compatibles remain very much compatible with the original IBM PC computers, although most of the components implement the compatibility in special backward compatibility modes used only during a system boot.