IBM PC compatible
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IBM PC compatible computers are those similar to the original
Early IBM PC compatibles used the same
Descendants of the IBM PC compatibles comprise the majority of personal computers on the market presently with the dominant
IBM decided in 1980 to market a low-cost single-user computer as quickly as possible in response[
IBM at first asked developers to avoid writing software that addressed the computer's hardware directly, and to instead make standard calls to BIOS functions that carried out hardware-dependent operations.
 This software would run on any machine using MS-DOS or PC-DOS. Software that directly addressed the hardware instead of making standard calls was faster, however; this was particularly relevant to games. Software addressing IBM PC hardware in this way would not run on MS-DOS machines with different hardware. The IBM PC was sold in high enough volumes to justify writing software specifically for it, and this encouraged other manufacturers to produce machines which could use the same programs,
Rumors of "lookalike", compatible computers, created without IBM's approval, began almost immediately after the IBM PC's release.   InfoWorld wrote on the first anniversary of the IBM PC that 
The dark side of an open system is its imitators. If the specs are clear enough for you to design peripherals, they are clear enough for you to design imitations. Apple ... has patents on two important components of its systems ... IBM, which reportedly has no special patents on the PC, is even more vulnerable. Numerous PC-compatible machines—the grapevine says 60 or more—have begun to appear in the marketplace.
By June 1983