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Generally known simply as PCs, IBM PC compatible computers are similar to the original IBM PC, XT, and AT. Able to use the same software and expansion cards, they were referred to as PC clones or IBM clones when they first came out.

IBM PC compatible a historical description only today, since IBM no longer manufactures personal computers and the PCs of today would not be compatible with the original IBM PC. In computer-speak, PC doesn't necessarily mean personal computer because the term is used to refer to computers running Microsoft Windows, as opposed to the Apple computers. While Apple's computers are indeed personal computers, the term PC is used to refer to personal computers other than the Apple Macintosh.

Since personal computers running versions of DOS or Linux are also referred to as PCs, the term mostly refers to personal computers other than those made by Apple.

When they were introduced in the early 1980s, the IBM PC compatibles took IBM out of the personal computer market, however.

IBM decided to get into the single-user computer market around 1980. releasing its IBM Model 5150 in August of 1981. This wasn't actually IBM's first home computer, but it was the first that had any success in the marketplace. Its first single-user computer was the IBM Model 5100, which was released in 1975. However, its $20,000 price tag didn't find a lot of buyers.

By 1980, although IBM had a stranglehold on the high-end computer market, the company saw the successes of Apple, Atari, Commodore, and Tandy in the home computer market, and made a decision to enter that market as well. It did so hurriedly, and its Model 5150 was not as powerful as some of the clones that it would soon be competing against.

The IBM Model 5150 was available with a choice of three operating systems: PC-DOS, CPM-86, or UCSD D-PASCAL System. Created for IBM by Microsoft, PC-DOS was originally the same as MS-DOS, although the two later forked into separate products.

Although the Model 5150 was more reasonably priced than its earlier home computer, at just over $1,200, some of the clones were cheaper and more powerful. Not only were new companies opening up to compete for the IBM PC compatible market, but Digital Equipment Corporation, Hewlett-Packard, Olivetti, Sanyo, Tandy/RadioShack, Texas Instruments, Wang, and Xerox introduced personal computers that supported MS-DOS, but were not completely compatible with the IBM PC.

Microsoft's competing OS was intended to operate on various types of hardware, all based on the 8086 processor. MS-DOS was available only as original equipment manufactured (OEM) product, as MS-DOS could not be purchased directly from Microsoft, and each version of DOS was packaged to match the characteristics of the given PC vendor, so there were several versions of DOS.

In 1983, four levels of compatibility were identified: operationally compatible, functionally compatible, data compatible, and incompatible. Incompatible machines were those that were unable to read PC disks.

As might be expected, there were several lawsuits involving patent infringements and so on but, in the end, the biggest loser was IBM, as end-users became less concerned with IBM compatibility, and more concerned with whether a particular machine was compatible with the software they liked. IBM became a minor player in its own market. By the end of the 1980s, IBM PC compatibles dominated the home and business markets, while IBM remained strong in the high-end corporate and institutional markets.

IBM fought back with its introduction of the OS/2 operating system in 1985, after which sales of IBM PCs rose. While the operating system was popular with users, IBM left the PC market in 2005 and discontinued its support for OS/2 in 2006.

The term IBM PC compatible is not commonly used today because most mainstream desktop and laptop computers are based on the PC architecture, IBM no longer produces PCs, and most of the competing hardware architectures have been either discontinued or relegated to niche markets. Rather, the common understanding is that there are two mainstream types of personal computers: the PC and the Mac.

Accepting this definition, this category is focused on personal computers that are not Macs. PC manufacturers, such as Acer, Asus, Compaq, Dell, Hewlett-Packard, and Toshiba, are appropriate topics for this category, along with any others, past or present. Informational sites focused on IBM PC compatibles may also be listed here. However, retail sales sites should be listed in the Shopping & eCommerce section of the directory.



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