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.From Altair to iPad 35 years of personal computer market share Ars Technica, October 2012 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. The editors asked 17 personal computer executives "Is 8-bit dead?" The response was mixed. Gary Kildall, author of the CP/M operating system, said "We're not too concerned that 8-bit stuff is going to die." Bill Gates said "We need the power of the 16-bit computers for good software design."
Some of the main manufacturers selling 8-bit business systems during this period were:
Acorn Computers Apple Computer Atari Inc. Commodore International Cromemco Digital Equipment Corporation Durango Systems Inc. Hewlett-Packard InterSystems Morrow Designs North Star Computers Ohio Scientific Olivetti Processor Technology Sharp South West Technical Products Corporation Tandy Corporation Zenith Data Systems/Heathkit
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.THE 8088, FIRST INTEL'S REALLY SUCCESSFUL CPU (JUNE 1979) – an article about the influence of the i8088 on old-computers.com. 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
Within a year of the IBM PC's introduction, Microsoft—the developer of its primary operating system, IBM PC DOS—licensed the operating system generically as MS-DOS to over 70 other companies. The first computer to achieve 100% PC compatibility was the Compaq Portable, released in November 1982, and it included a clean-room engineered BIOS; it remained the most compatible clone into 1984. Before the PC dominated the market, however, most systems were not clones of the IBM PC design, but had different internal designs, and ran Digital Research's CP/M. Also, Compaq did not offer its clean-room engineered BIOS to other computer manufacturers.
By early 1983 the PC's MS-DOS and Intel 8088 had become a standard to emulate; an example is the TI Professional, which does not use the company's own 16-bit CPU. TI, Wang Laboratories, Zenith Data Systems, and others with existing proprietary systems offered MS-DOS systems with some amount of IBM compatibility. The IBM PC was difficult to obtain for several years after its introduction, but many vendors intentionally avoided full IBM compatibility because they expected that the market for what InfoWorld described as "ordinary PC clones" would decline. They feared the fate of companies that sold computers plug-compatible with IBM mainframes in the 1960s and 1970s—many of which went bankrupt after IBM changed specifications—and believed that a market existed for personal computers with a similar selection of software to the IBM PC, but with different, superior hardware. Benjamin Rosen was an investor in Compaq, but his Rosen Electronics Letter predicted in February 1983 that the Professional "should be one of the year's bigger successes" despite not 100% compatible. Many vendors used such an approach into 1984.
While Microsoft used a sophisticated installer with its DOS programs like Multiplan that provided device drivers for many non IBM PC-compatible computers, most other software vendors did not. Columbia University discussed the difficulty of having Kermit support many different clones and MS-DOS computers. Peter Norton, who earlier had encouraged vendors to write software that ran on many different computers, by early 1985 admitted—after experiencing the difficulty of doing so while rewriting Norton Utilities—that "there's no practical way for most software creators to write generic software". Although TI launched the Professional with more than 100 software packages available immediately, dealers found carrying multiple versions of software for clones of varying levels of compatibility to be difficult.
To get the best results out of the 8088's modest performance, many popular software applications were written specifically for the IBM PC. The developers of these programs opted to write directly to the computer's (video) memory and peripheral chips, bypassing MS-DOS and the BIOS. For example, a program might directly update the video refresh memory, instead of using MS-DOS calls and device drivers to alter the appearance of the screen. Many notable software packages, such as the spreadsheet program Lotus 1-2-3, and Microsoft's Microsoft Flight Simulator 1.0, directly accessed the IBM PC's hardware, bypassing the BIOS, and therefore did not work on computers that were even trivially different from the IBM PC. This was especially common among PC games. As a result, the systems that were not fully IBM PC-compatible could not run this software, and quickly became obsolete. Rendered obsolete with them was the CP/M-inherited concept of OEM versions of MS-DOS meant to run (through BIOS calls) on non IBM-PC hardware.
Cloning the PC BIOS In 1984, Phoenix Technologies began licensing its clone of the IBM PC BIOS. The Phoenix BIOS and competitors such as AMI BIOS made it possible for anyone to market a PC compatible computer, without having to develop a compatible BIOS like Compaq.
Decline of the Intel 80186 Although based on the i8086 and enabling the creation of relatively low-cost x86-based systems, the Intel 80186 quickly lost appeal for x86-based PC builders because the supporting circuitry inside the Intel 80186 chip was incompatible with those used in the standard PC chipset as implemented by IBM. It was very rarely used in personal computers after 1982.
Domination of the clones
"Is it PC compatible?"
While predicting success for the TI Professional in 1983, Rosen Electronics Letter added "we'd rather it had been completely compatible with the PC", stating that "we kow of one case (and there will be many)" where a customer chose the PC because of "the name, the trustworthiness and most important of all the identity of IBM". One year after the Rosen prediction, BYTE described how "the personal computer market seems to be shadowed under a cloud of compatibility: the drive to be compatible with the IBM Personal Computer family has assumed near-fetish proportions", which it stated was "inevitable in the light of the phenomenal market acceptance of the IBM PC". The magazine cited the announcement by North Star in fall 1983 of its first PC-compatible microcomputer. Founded in 1976, North Star had long been successful with 8-bit S-100 bus products, and had introduced proprietary 16-bit products, but now the company acknowledged that the IBM PC had become a "standard", one which North Star needed to follow. BYTE described the announcement as representative of the great impact IBM had made on the industry:
The magazine worried in 1984 that "IBM's burgeoning influence in the PC community is stifling innovation because so many other companies are mimicking Big Blue". Those that had "tried to improve on the PC standard", InfoWorld wrote, "unanimously got burned [and] stifled innovation". The TI and Wang computers were among the failures, as were the DEC and Data General products, despite TI's good reviews and others' success in competing against IBM minicomputers. Even IBM's mainframe rivals, the BUNCH, introduced their own compatibles despite earlier viewing such a small computer as a "toy"; they and other vendors of large computers had lost sales to existing customers that would have preferred to buy from them if possible. Sperry stated that its clone was "late to the dance" so as to be more compatible. When Hewlett-Packard (HP) introduced the Vectra in 1985, InfoWorld stated that the company was "responding to demands from its customers for full IBM PC compatibility". By contrast, as late as 1991, Computerworld wrote of DEC's inability to sell PCs to its customers, which bought them from HP, Compaq, and others.
Some of the largest vendors, like Honeywell Information Systems and Tandem Computers, explicitly admitted that their products were not innovative, but were what customers wanted. John V. Lombardi wrote in InfoWorld that the Epson Equity "is the least innovative [of Epson computers] and, ironically, is probably the most likely to succeed. It is in every way a plain vanilla IBM PC clone". Stating that compatibles were a commodity like televisions with falling prices, Zenith Data Systems's CEO said "Basically, we move boxes".