PC Hardware in a Nutshell, 3rd Edition

PCs Defined

Who decides what is and what is not a PC? That question is not as trivial as it sounds, because there has never been (and probably will never be) an all-embracing de jure standard to define the PC. IBM created the de facto PC standard (and trademarked the name) when it shipped the first IBM Personal Computer in 1981. For more than five years, until its introduction of the ill-fated proprietary PS/2 line in 1987, IBM defined the PC standard. For a short time thereafter, some considered that Compaq defined the standard. But the days when any PC maker defined the PC standard are far in the past.

These days, Intel and Microsoft jointly define the de facto PC standard. In fact, a good working definition of a PC is a computer that uses an Intel or compatible processor and can run a Microsoft operating system. Any computer that meets both requirements—a so-called Wintel computer—is a PC. A computer that does not is not. Computers based on some Intel processors cannot run any Microsoft operating system, and thus are not PCs. Conversely, some computers with non-Intel processors can run Microsoft operating systems, but do not qualify as PCs. For example, DEC Alpha minicomputers running Windows NT 4 are not PCs.

Two formal documents, described in the following sections, define the joint Intel/Microsoft standards for systems and components you are likely to be working with. These standards are de facto in the sense that system and peripheral makers are not required to comply ...