Following the introduction of the IBM Personal Computer (IBM PC) in 1981, many other personal computer architectures became extinct within just a few years. It led to a wave of IBM PC compatible systems being released.
Before the IBM PC's introduction Before the IBM PC was introduced, the personal computer market was dominated by systems using the 6502 and Z80 8-bit microprocessors, such as the TRS 80, PET, and Apple II, which used proprietary operating systems, and by computers running CP/M. After IBM introduced the IBM PC, it was not until 1984 that IBM PC and clones became the dominant computers. In 1983, Byte forecast that by 1990, IBM would command only 11% of business computer sales. Commodore was predicted to hold a slim lead in a highly competitive market, at 11.9%. Around 1978, several 16-bit CPUs became available. Examples included the Data General mN601, the Fairchild 9440, the Ferranti F100-L, the General Instrument CP1600 and CP1610, the National Semiconductor INS8900, Panafacom's MN1610, Texas Instruments' TMS9900, and, most notably, the Intel 8086. These new processors were expensive to incorporate in personal computers, as they used a 16-bit data bus and needed rare (and thus expensive) 16-bit peripheral and support chips. More than 50 new business-oriented personal computer systems came on the market in the year before IBM released the IBM PC. Very few of them used a 16- or 32-bit microprocessor, as 8-bit systems were generally believed by the vendors to be perfectly adequate, and the Intel 8086 was too expensive to use. Some of the main manufacturers selling 8-bit business systems during this period were:
The IBM PC On August 12, 1981, IBM released the IBM Personal Computer. One of the most far-reaching decisions made for IBM PC was to use an open architecture, leading to a large market for third party add-in boards and applications; but finally also to many competitors all creating "IBM-compatible" machines. The IBM PC used the then-new Intel 8088 processor. Like other 16-bit CPUs, it could access up to 1 megabyte of RAM, but it used an 8-bit-wide data bus to memory and peripherals. This design allowed use of the large, readily available, and relatively inexpensive family of 8-bit-compatible support chips. IBM decided to use the Intel 8088 after first considering the Motorola 68000 and the Intel 8086, because the other two were considered to be too powerful for their needs. Although already established rivals like Apple and Radio Shack had many advantages over the company new to microcomputers, IBM's reputation in business computing allowed the IBM PC architecture to take a substantial market share of business applications, and many small companies that sold IBM-compatible software or hardware rapidly grew in size and importance, including Tecmar, Quadram, AST Research, and Microsoft. As of mid-1982, three other mainframe and minicomputer companies sold microcomputers, but unlike IBM, Hewlett-Packard, Xerox, and Control Data Corporation chose the CP/M operating system. Many other companies made "business personal computers" using their own proprietary designs, some still using 8-bit microprocessors. The ones that used Intel x86 processors often used the generic, non-IBM-compatible specific version of MS-DOS or CP/M-86, just as 8-bit systems with an Intel 8080 compatible CPU normally used CP/M.
The use of MS-DOS on non-IBM PC compatible systems
[Bill] Gates predicts that in the next six to nine months, several 8086 machines will be introduced. Just because a machine is based on the same processor, he explains, does not mean that all PC software will run on it. In some cases, software bypasses the operating system and uses specific hardware characteristics of the PC.
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