AnIBM PC compatible is anypersonal computer that ishardware- andsoftware-compatible with theIBM Personal Computer (IBM PC) and itssubsequent models. Like the original IBM PC, an IBM PC–compatible computer uses anx86-basedcentral processing unit, sourced either fromIntel or asecond source likeAMD,Cyrix orother vendors such asTexas Instruments,Fujitsu,OKI,Mitsubishi orNEC and is capable of using interchangeable commodity hardware such asexpansion cards. Initially such computers were referred to asPC clones,IBM clones orIBM PC clones, but the term "IBM PC compatible" is now a historical description only, as the vast majority ofmicrocomputers produced since the 1990s are IBM compatible.IBM itself no longer sells personal computers,having sold its division toLenovo in 2005. "Wintel" is a similar description that is more commonly used for modern computers.
The designation "PC", as used in much ofpersonal computer history, has not meant "personal computer" generally, but rather an x86 computer capable of running the same software that a contemporary IBM or Lenovo PC could. The term was initially in contrast to the variety ofhome computer systems available in the early 1980s, such as theApple II,TRS-80, andCommodore 64. Later, the term was primarily used in contrast toCommodore'sAmiga andApple'sMacintosh computers.
These "clones" duplicated almost all the significant features of the original IBM PC architectures. This was facilitated by IBM's choice ofcommodity hardware components, which were cheap, and by various manufacturers' ability toreverse-engineer theBIOSfirmware using a "clean room design" technique.Columbia Data Products built the first clone of the IBMpersonal computer, theMPC 1600[1] by a clean-room reverse-engineered implementation of its BIOS. Other rival companies,Corona Data Systems,Eagle Computer, and the Handwell Corporation were threatened with legal action by IBM, who settled with them. Soon after in 1982,Compaq released the very successfulCompaq Portable, also with a clean-room reverse-engineered BIOS, and also not challenged legally by IBM.
Early IBM PC compatibles used the samecomputer buses as their IBM counterparts, switching from the8-bit IBM PC and XT bus to the16-bit IBM AT bus with the release of the AT. IBM's introduction of the proprietaryMicro Channel architecture (MCA) in itsPersonal System/2 (PS/2) series resulted in the establishment of theExtended Industry Standard Architecture busopen standard by a consortium of IBM PC compatible vendors, redefining the 16-bit IBM AT bus as theIndustry Standard Architecture (ISA) bus.[2] Additional bus standards were subsequently adopted to improve compatibility between IBM PC compatibles, including theVESA Local Bus (VLB),Peripheral Component Interconnect (PCI), and theAccelerated Graphics Port (AGP).
Descendants of the x86 IBM PC compatibles, namely64-bit computers based on "x86-64/AMD64" chipscomprise the majority of desktop computers on the market as of 2021, with the dominantoperating system beingMicrosoft Windows. Interoperability with the bus structure and peripherals of the original PC architecture may be limited or non-existent. Many modern computers are unable to use old software or hardware that depends on portions of the IBM PC compatible architecture which are missing or do not have equivalents in modern computers. For example, computers which boot usingUnified Extensible Firmware Interface-based firmware that lack a Compatibility Support Module, or CSM, required to emulate the old BIOS-based firmware interface, or have their CSMs disabled, cannot natively runMS-DOS since MS-DOS depends on a BIOS interface to boot.
Only theMacintosh had kept significant market share without having compatibility with the IBM PC, although that changed during the Intel Macs era runningMac OS X, oftendual-booting Windows withBoot Camp.
IBM decided in 1980 to market a low-cost single-user computer as quickly as possible. On August 12, 1981, the firstIBM PC went on sale. There were threeoperating systems (OS) available for it. The least expensive and most popular wasPC DOS made byMicrosoft. In a crucial concession, IBM's agreement allowed Microsoft to sell its own version,MS-DOS, for non-IBM computers. The only component of the original PC architecture exclusive to IBM was theBIOS (Basic Input/Output System).
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.[3] 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 (for example, thePC-98). The IBM PC was sold in high enough volumes to justify writing software specifically for it, and this encouraged other manufacturers to produce machines that could use the same programs,expansion cards, and peripherals as the PC. Thex86 computer marketplace rapidly excluded all machines which were not hardware-compatible or software-compatible with the PC. The640 KB barrier on "conventional" system memory available to MS-DOS is a legacy of that period; other non-clone machines, while subject to a limit, could exceed 640 KB.
Rumors of "lookalike," compatible computers, created without IBM's approval, began almost immediately after the IBM PC's release.[4][5]InfoWorld wrote on the first anniversary of the IBM PC that[6]
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 says60 or more—have begun to appear in the marketplace.
By June 1983PC Magazine defined "PC 'clone'" as "a computer [that can] accommodate the user who takes a disk home from an IBM PC, walks across the room, and plugs it into the 'foreign' machine".[7] Demand for the PC by then was so strong that dealers received 60% or less of the inventory they wanted,[8] and many customers purchased clones instead.[9][10][11]Columbia Data Products produced the first computer more or less compatible with the IBM PC standard during June 1982, soon followed byEagle Computer.Compaq announced its first product, an IBM PC compatible in November 1982, theCompaq Portable. The Compaq was the first sewing machine-sizedportable computer that was essentially 100% PC-compatible. The court decision inApple v. Franklin, was that BIOS code was protected by copyright law, but it couldreverse-engineer the IBM BIOS and then write its own BIOS usingclean room design. Note this was over a year after Compaq released the Portable. The money and research put into reverse-engineering the BIOS was a calculated risk.
At the same time, many manufacturers such asTandy/RadioShack,Xerox,Hewlett-Packard,Digital Equipment Corporation,Sanyo,Texas Instruments,Tulip,Wang andOlivetti introduced personal computers that supported MS-DOS, but were not completely software- or hardware-compatible with the IBM PC.
Tandy described theTandy 2000, for example, as having a "'next generation' true 16-bit CPU", and with "More speed. More disk storage. More expansion" than the IBM PC or "other MS-DOS computers".[12] While admitting in 1984 that many PC DOS programs did not work on the computer, the company stated that "the most popular, sophisticated software on the market" was available, either immediately or "over the next six months".[13]
Like IBM, Microsoft's apparent intention was that application writers would write to theapplication programming interfaces in MS-DOS or the firmware BIOS, and that this would form what would now be termed ahardware abstraction layer. Each computer would have its ownOriginal Equipment Manufacturer (OEM) version of MS-DOS, customized to its hardware. Any software written for MS-DOS would operate on any MS-DOS computer, despite variations in hardware design.
This expectation seemed reasonable in the computer marketplace of the time. Until then Microsoft's business was based primarily on computer languages such asBASIC. The established small system operating software wasCP/M fromDigital Research which was in use both at the hobbyist level and by the more professional of those using microcomputers. To achieve such widespread use, and thus make the product viable economically, the OS had to operate across a range of machines from different vendors that had widely varying hardware. Those customers who needed other applications than the starter programs could reasonably expect publishers to offer their products for a variety of computers, on suitable media for each.
Microsoft's competing OS was intended initially to operate on a similar varied spectrum of hardware, although all based on the 8086 processor. Thus, MS-DOS was for several years sold only as an OEM product. There was no Microsoft-branded MS-DOS: MS-DOS could not be purchased directly from Microsoft, and each OEM release was packaged with thetrade dress of the given PC vendor. Malfunctions were to be reported to the OEM, not to Microsoft. However, as machines that were compatible with IBM hardware—thus supporting direct calls to the hardware—became widespread, it soon became clear that the OEM versions of MS-DOS were virtually identical, except perhaps for the provision of a few utility programs.
MS-DOS provided adequate functionality for character-oriented applications such as those that could have been implemented on a text-onlyterminal. Had the bulk of commercially important software been of this nature, low-level hardware compatibility might not have mattered. However, in order to provide maximum performance and leverage hardware features (or work around hardware bugs), PC applications quickly developed beyond the simple terminal applications that MS-DOS supported directly.Spreadsheets,WYSIWYGword processors,presentation software and remotecommunication software established new markets that exploited the PC's strengths, but required capabilities beyond what MS-DOS provided. Thus, from very early in the development of the MS-DOS software environment, many significant commercial software products were written directly to the hardware, for a variety of reasons:
| Computer name | Manufacturer | Date introduced | CPU | clock rate | Max RAM | Floppy disk capacity | Notable features |
|---|---|---|---|---|---|---|---|
| Hyperion | Dynalogic | Jan 1983 | 8088 | 4.77 MHz | 640 KB | 320 KB | Canadian, licensed[15][16] but never sold[citation needed] byCommodore[17] |
| Olivetti M24/AT&T 6300 / Logabax Persona 1600 | Olivetti, marketed byAT&T | 1983 (AT&T 6300 June 1984) | 8086 | 8 MHz (later 10 MHz) | 640 KB | 360 KB (later 720 KB) | true IBM compatible;[18][19] optional 640x400 color graphics |
| Zenith Z-100 | Zenith Data Systems | June 1982 | 8088 | 4.77 MHz | 768 KB | 360 KB | optional 8 color 640x255 graphics, external 8" floppy drives[20] |
| HP-150 | Hewlett-Packard | Nov 1983 | 8088 | 8 MHz | 640 KB | 270 KB (later 710 KB) | primitive touchscreen[21] |
| Compaq Portable | Compaq | Jan 1983 | 8088 | 4.77 MHz | 640 KB | 360 KB | sold as a true IBM compatible[10][11][22][23] |
| Compaq Deskpro | Compaq | 1984 | 8086 | 8 MHz | 640 KB | 360 KB | sold as true IBM XT compatible[24] |
| MPC 1600 | Columbia Data Products | June 1982 | 8088 | 4.77 MHz | 640 KB | 360 KB | true IBM compatible, credited as first PC clone[7][25][26][27] |
| Eagle PC / 1600 series | Eagle Computer | 1982 | 8086 | 4.77 MHz | 640 KB | 360 KB | 750×352 mono graphics, first 8086 CPU[28] |
| TI Professional Computer | Texas Instruments | Jan 1983 | 8088 | 5 MHz | 256 KB | 320 KB | 720x300 color graphics[29][30][31] |
| DEC Rainbow | Digital Equipment Corporation | 1982 | 8088 | 4.81 MHz | 768 KB | 400 KB | 132x24 text mode, 8088 andZ80 CPUs[32][33] |
| Wang PC | Wang Laboratories | Aug 1985 | 8086 | 8 MHz | 512 KB | 360 KB | 800x300 mono graphics[34] |
| MBC-550 | Sanyo | 1982 | 8088 | 3.6 MHz | 256 KB | 360 KB (later 720 KB) | 640x200 8 color graphics (R, G, B bitplanes)[35] |
| Apricot PC | Apricot Computers | 1983 | 8086 | 4.77 MHz | 768 KB | 720 KB | 800x400 mono graphics, 132x50 text mode[36] |
| TS-1603 | TeleVideo | Apr 1983 | 8088 | 4.77 MHz | 256 KB | 737 KB | keyboard had palm rests, 16 function keys;[37] built-in modem |
| Tava PC | Tava Corporation | Oct 1983 | 8088 | 4.77 MHz | 640 KB | 360 KB | true IBM compatible, credited as first private-label clone sold by manufacturer's stores[38][39][40][41] |
| Tandy 2000 | Tandy Corporation | Sep 1983 | 80186 | 8 MHz | 768 KB | 720 KB | redefinable character set,[citation needed] optional 640x400 8-color[42] or mono graphics |
The first thing to think about when considering an IBM-compatible computer is, "How compatible is it?"
— BYTE, September 1983[43]
In May 1983, Future Computing defined four levels of compatibility:[44]
During development, Compaq engineers found thatMicrosoft Flight Simulator would not run because of whatsubLOGIC'sBruce Artwick described as "a bug in one of Intel's chips", forcing them to make their new computerbug compatible with the IBM PC.[45] At first, few clones other than Compaq's offered truly full compatibility.[46]Jerry Pournelle purchased an IBM PC in mid-1983, "rotten keyboard and all", because he had "four cubic feet of unevaluated software, much of which won't run on anything but an IBM PC. Although a lot of machines claim to be 100 percent IBM PC compatible, I've yet to have one arrive ... Alas, a lot of stuff doesn't run with Eagle, Z-100,Compupro, or anything else we have around here".[47] Columbia Data Products's November 1983 sales brochure stated that during tests with retail-purchased computers in October 1983, its own and Compaq's products were compatible with all tested PC software, while Corona and Eagle's were less compatible.[48]Columbia University reported in January 1984 thatKermit ran without modification on Compaq and Columbia Data Products clones, but not on those from Eagle or Seequa. Other MS-DOS computers also required custom code.[49]
By December 1983 Future Computing stated that companies like Compaq, Columbia Data Products, and Corona that emphasized IBM PC compatibility had been successful, while non-compatible computers had hurt the reputations of others like TI and DEC despite superior technology. At a San Francisco meeting it warned 200 attendees, from many American and foreign computer companies as well as IBM itself, to "Jump on the IBM PC-compatible bandwagon—quickly, and as compatibly as possible".[50] Future Computing said in February 1984 that some computers were "press-release compatible", exaggerating their actual compatibility with the IBM PC.[51] Many companies were reluctant to have their products' PC compatibility tested. WhenPC Magazine requested samples from computer manufacturers that claimed to produce compatibles for an April 1984 review, 14 of 31 declined.[52][53] Corona specified that "Our systems run all software that conforms to IBM PC programming standards. And the most popular software does."[54] When aBYTE journalist asked to testPeachtext at the Spring 1983COMDEX, Corona representatives "hemmed and hawed a bit, but they finally led me ... off in the corner where no one would see it should it fail". The magazine reported that "Their hesitancy was unnecessary. The disk booted up without a problem".[43]Zenith Data Systems was bolder, bragging that its Z-150 ran all applications people brought to test with at the 1984West Coast Computer Faire.[55]
Creative Computing in 1985 stated, "we reiterate our standard line regarding the IBM PC compatibles: try the package you want to use before you buy the computer."[56] Companies modified their computers' BIOS to work with newly discovered incompatible applications,[14] and reviewers and users developedstress tests to measure compatibility; by 1984 the ability to operate Lotus 1-2-3 andFlight Simulator became the standard,[10][57][14][58][56][59] with compatibles specifically designed to run them[55][45] and prominently advertising their compatibility.[60]
IBM believed that some companies such as Eagle, Corona, and Handwell infringed on its copyright, and afterApple Computer, Inc. v. Franklin Computer Corp. successfully forced the clone makers to stop using the BIOS. ThePhoenix BIOS in 1984, however, and similar products such asAMI BIOS, permitted computer makers to legally build essentially 100%-compatible clones without having to reverse-engineer the PC BIOS themselves.[61][62][63] A September 1985InfoWorld chart listed seven compatibles with256 KB RAM, two disk drives, and monochrome monitors for$1,495 to$2,320, while the equivalent IBM PC cost$2,820.[64] The Zenith Z-150[57] and inexpensiveLeading Edge Model D are even compatible with IBM proprietary diagnostic software, unlike the Compaq Portable.[65] By 1986Compute! stated that "clones are generally reliable and about 99 percent compatible",[66] and a 1987 survey in the magazine of the clone industry did not mention software compatibility, stating that "PC by now has come to stand for a computer capable of running programs that are managed by MS-DOS".[67]
The main reason why an IBM standard is not worrying is that it can help competition to flourish. IBM will soon be as much a prisoner of its standards as its competitors are. Once enough IBM machines have been bought, IBM cannot make sudden changes in their basic design; what might be useful for shedding competitors would shake off even more customers.
— The Economist, November 1983[68]
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In February 1984Byte wrote that "IBM's burgeoning influence in the PC community is stifling innovation because so many other companies are mimicking Big Blue",[69] butThe Economist stated in November 1983, "The main reason why an IBM standard is not worrying is that it can help competition to flourish".[68]
By 1983, IBM had about 25% of sales of personal computers between$1,000 and$10,000, and computers with some PC compatibility were another 25%.[51] As the market and competition grew IBM's influence diminished. Writing that even "IBM has to continue to be IBM compatible", in November 1985PC Magazine stated "Now that it has created the [PC] market, the market doesn't necessarily need IBM for the machines. It may depend on IBM to set standards and to develop higher-performance machines, but IBM had better conform to existing standards so as to not hurt users".[70] Observers noted IBM's silence when the industry that year quickly adopted theexpanded memory standard, created by Lotus and Intel without IBM's participation.[71] In January 1987,Bruce Webster wrote inByte of rumors that IBM would introduce proprietary personal computers witha proprietary operating system: "Who cares? If IBM does it, they will most likely just isolate themselves from the largest marketplace, in which they really can't compete anymore anyway". He predicted that in 1987 the market "will complete its transition from an IBM standard to an Intel/MS-DOS/expansion bus standard ... Folks aren't so much concerned about IBM compatibility as they are about Lotus 1-2-3 compatibility".[72] By 1992,Macworld stated that because of clones, "IBM lost control of its own market and became a minor player with its own technology".[73]
The Economist predicted in 1983 that "IBM will soon be as much a prisoner of its standards as its competitors are", because "Once enough IBM machines have been bought, IBM cannot make sudden changes in their basic design; what might be useful for shedding competitors would shake off even more customers".[68] After theCompaq Deskpro 386 became the first 80386-based PC,PC wrote that owners of the new computer did not need to fear that future IBM products would be incompatible with the Compaq, because such changes would also affect millions of real IBM PCs: "In sticking it to the competition, IBM would be doing the same to its own people".[74] After IBM announced theOS/2-oriented PS/2 line in early 1987, sales of existing DOS-compatible PC compatibles rose, in part because the proprietary operating system was not available.[75] In 1988,Gartner Group estimated that the public purchased 1.5 clones for every IBM PC.[76] By 1989 Compaq was so influential that industry executives spoke of "Compaq compatible", with observers stating that customers saw the company as IBM's equal[77] or superior.[78] A 1990American Institute of Certified Public Accountants member survey found that 23% of respondents used IBM computer hardware, and 16% used Compaq.[79]
After 1987, IBM PC compatibles dominated both the home and business markets of commodity computers,[80] with other notable alternative architectures being used in niche markets, like theMacintosh computers offered byApple Inc. and used mainly fordesktop publishing at the time, the aging 8-bitCommodore 64 which was selling for $150 by this time and became the world's bestselling computer, the 32-bitCommodore Amiga line used fortelevision andvideo production and the 32-bitAtari ST used by the music industry. However, IBM itself lost the main role in the market for IBM PC compatibles by 1990. A few events in retrospect are important:
Despite popularity of itsThinkPad set of laptop PC's, IBM finally relinquished its role as a consumer PC manufacturer during April 2005, when itsold its laptop and desktop PC divisions (ThinkPad/ThinkCentre) toLenovo forUS$1.75 billion.
As of October 2007,Hewlett-Packard andDell had the largest shares of the PC market in North America. They were also successful overseas, withAcer,Lenovo, andToshiba also notable. Worldwide, a huge number of PCs are "white box" systems assembled by myriad local systems builders. Despite advances of computer technology, the IBM PC compatibles remained very much compatible with the original IBM PC computers, although most of the components implement the compatibility in specialbackward compatibility modes used only during asystemboot. It was often more practical to run old software on a modern system using anemulator rather than relying on these features.
In 2014 Lenovo acquired IBM's x86-based server (System x) business forUS$2.1 billion.
One of the strengths of the PC-compatible design is its modular hardware design. End-users could readily upgrade peripherals and, to some degree, processor and memory without modifying the computer'smotherboard or replacing the whole computer, as was the case with many of themicrocomputers of the time. However, as processor speed and memory width increased, the limits of the original XT/AT bus design were soon reached, particularly when driving graphics video cards. IBM did introduce an upgraded bus in theIBM PS/2 computer that overcame many of the technical limits of the XT/AT bus, but this was rarely used as the basis for IBM-compatible computers since it required license payments to IBM both for the PS/2 bus and any prior AT-bus designs produced by the company seeking a license. This was unpopular with hardware manufacturers and several competing bus standards were developed by consortiums, with more agreeable license terms. Various attempts to standardize the interfaces were made, but in practice, many of these attempts were either flawed or ignored. Even so, there were many expansion options, and despite the confusion of its users, the PC compatible design advanced much faster than other competing designs of the time, even if only because of its market dominance.
During the 1990s, IBM's influence on PC architecture started to decline. "IBM PC compatible" becomes "Standard PC" in 1990s, and later "ACPI PC" in 2000s. An IBM-brand PC became the exception rather than the rule. Instead of placing importance on compatibility with the IBM PC, vendors began to emphasize compatibility withWindows. In 1993, a version ofWindows NT was released that could operate on processors other than thex86 set. While it required that applications be recompiled, which most developers did not do, its hardware independence was used forSilicon Graphics (SGI) x86 workstations–thanks to NT'sHardware abstraction layer (HAL), they could operate NT (and its vast application library)[clarification needed].
No mass-market personal computer hardware vendor dared to be incompatible with the latest version of Windows, and Microsoft's annualWinHEC conferences provided a setting in which Microsoft could lobby for—and in some cases dictate—the pace and direction of the hardware of the PC industry. Microsoft and Intel had become so important to the ongoing development of PC hardware that industry writers began using the wordWintel to refer to the combined hardware-software system.
This terminology itself is becoming a misnomer, as Intel has lost absolute control over the direction of x86 hardware development withAMD'sAMD64. Additionally, non-Windows operating systems likemacOS andLinux have established a presence on the x86 architecture.
Although the IBM PC was designed for expandability, the designers could not anticipate the hardware developments of the 1980s, nor the size of the industry they would engender. To make things worse, IBM's choice of theIntel 8088 for the CPU introduced several limitations for developing software for the PC compatible platform. For example, the 8088 processor only had a 20-bit memoryaddressing space. To expandPCs beyond one megabyte, Lotus, Intel, and Microsoft jointly createdexpanded memory (EMS), a bank-switching scheme to allow more memory provided by add-in hardware, and accessed by a set of four 16-kilobyte "windows" inside the 20-bit addressing. Later, Intel CPUs had larger address spaces and could directly address 16 MB (80286) or more, causing Microsoft to developextended memory (XMS) which did not require additional hardware.
"Expanded" and "extended" memory have incompatible interfaces, so anyone writing software that used more than one megabyte had to provide for both systems for the greatest compatibility until MS-DOS began including EMM386, which simulated EMS memory using XMS memory. Aprotected mode OS can also be written for the 80286, but DOS application compatibility was more difficult than expected, not only because most DOS applications accessed the hardware directly, bypassing BIOS routines intended to ensure compatibility, but also that most BIOS requests were made by the first 32 interrupt vectors, which were marked as "reserved" for protected mode processor exceptions by Intel.
Video cards suffered from their own incompatibilities. There was no standard interface for using higher-resolutionSVGA graphics modes supported by later video cards. Each manufacturer developed their own methods of accessing the screen memory, including different mode numberings and differentbank switching arrangements. The latter were used to address large images within a single 64 KB segment of memory. Previously, the VGA standard had usedplanar video memory arrangements to the same effect, but this did not easily extend to the greater color depths and higher resolutions offered by SVGA adapters. An attempt at creating a standard namedVESA BIOS Extensions (VBE) was made, but not all manufacturers used it.
When the 386 was introduced, again aprotected mode OS could be written for it. This time, DOS compatibility was much easier because ofvirtual 8086 mode. Unfortunately programs could not switch directly between them, so eventually, some new memory-model APIs were developed,VCPI andDPMI, the latter becoming the most popular.
Because of the great number of third-party adapters and no standard for them, programming the PC could be difficult. Professional developers would operate a large test-suite of various known-to-be-popular hardware combinations.
To give consumers some idea of what sort of PC they would need to operate their software, theMultimedia PC (MPC) standard was set during 1990. A PC that met the minimum MPC standard could be marketed with the MPC logo, giving consumers an easy-to-understand specification to look for. Software that could operate on the most minimally MPC-compliant PC would be guaranteed[who?] to operate on any MPC. The MPC level 2 and MPC level 3 standards were set later, but the term "MPC compliant" never became popular. After MPC level 3 during 1996, no further MPC standards were established.
| Operating system (vendor) | 1990 | 1992 |
|---|---|---|
| MS-DOS (Microsoft) | 11,648 (of which 490 with Windows) | 18,525 (of which 11,056 with Windows) |
| PC DOS (IBM) | 3,031 | 2,315 |
| DR DOS (Digital Research/Novell) | 1,737 | 1,617 |
| Macintosh System (Apple) | 1,411 | 2,570 |
| Unix (various) | 357 | 797 |
| OS/2 (IBM/Microsoft) | 0 | 409 |
| Others (NEC,Commodore etc.) | 5,079 | 4,458 |
By the late 1990s, the success ofMicrosoft Windows had driven rival commercialoperating systems into near-extinction, and had ensured that the "IBM PC compatible" computer was the dominantcomputing platform. This meant that if a developer made their software only for theWintel platform, they would still be able to reach the vast majority of computer users. The only major competitor to Windows with more than a few percentage points ofmarket share wasApple Inc.'sMacintosh. The Mac started out billed as "the computer for the rest of us", but high prices and closed architecture drove the Macintosh into an education anddesktop publishing niche, from which it only emerged in the mid-2000s. By the mid-1990s the Mac's market share had dwindled to around 5% and introducing a new rival operating system had become too risky a commercial venture. Experience had shown that even if an operating system was technically superior to Windows, it would be a failure in the market (BeOS andOS/2 for example). In 1989,Steve Jobs said of his newNeXT system, "It will either be the last new hardware platform to succeed, or the first to fail."[citation needed] Four years later in 1993, NeXT announced it was ending production of theNeXTcube and portingNeXTSTEP to Intel processors.
Very early on in PC history, some companies introduced their own XT-compatiblechipsets. For example,Chips and Technologies introduced their82C100 XT Controller which integrated and replaced six of the original XT circuits: one8237 DMA controller, one8253 interrupt timer, one8255 parallel interface controller, one8259 interrupt controller, one8284 clock generator, and one8288 bus controller. Similar non-Intel chipsets appeared for the AT-compatibles, for example OPTi's 82C206 or 82C495XLC which were found in many 486 and early Pentium systems.[88] The x86 chipset market was very volatile though. In 1993,VLSI Technology had become the dominant market player only to be virtually wiped out by Intel a year later. Intel has been the uncontested leader ever since.[89] As the "Wintel" platform gained dominance Intel gradually abandoned the practice of licensing its technologies to other chipset makers; in 2010 Intel was involved in litigation related to their refusal to license their processor bus and related technologies to other companies likeNvidia.[90]
Companies such asAMD andCyrix developed alternative x86 CPUs that were functionally compatible with Intel's. Towards the end of the 1990s, AMD was taking an increasing share of the CPU market for PCs. AMD even ended up playing a significant role in directing the development of the x86 platform when its Athlon line of processors continued to develop the classic x86 architecture as Intel deviated with itsNetBurst architecture for the Pentium 4 CPUs and theIA-64 architecture for theItanium set of server CPUs. AMD developed AMD64, the first major extension not created by Intel, which Intel later adopted asx86-64. During 2006 Intel began abandoning NetBurst with the release of their set of "Core" processors that represented a development of the earlier Pentium III.
A major alternative to Wintel domination is the rise of alternative operating systems since the early 2000s, which marked as the start of thepost-PC era.[citation needed] This would include both the rapid growth of the smartphones (using Android or iOS) as an alternative to the personal computer; and the increasing prevalence of Linux and Unix-like operating systems in the server farms of large corporations such as Google or Amazon.
The term "IBM PC compatible" is not commonly used presently because[citation needed] many current mainstream desktop and laptop computers are based on the PC architecture,[91][92][93][94]: 39–40 and IBM no longer makes PCs. The competing hardware architectures have either been discontinued or, like theAmiga, have been relegated to niche, enthusiast markets. In the past, the most successful exception wasApple'sMacintosh platform, which used non-Intel processors from its inception. Although Macintosh was initially based on theMotorola 68000 series, then transitioned to thePowerPC architecture, Macintosh computerstransitioned to Intel processors beginning in 2006. Until 2020 Macintosh computers shared the same system architecture as their Wintel counterparts and couldboot Microsoft Windows without aDOS Compatibility Card. However, with thetransition to the internally developedARM-basedApple silicon, they are again the exception to IBM compatibility.
The processor speed and memory capacity of modern PCs are manyorders of magnitude greater than they were for the originalIBM PC and yet backwards compatibility has been largely maintained – a 32-bit operating system released during the 2000s[update] can still operate many of the simpler programs written for the OS of the early 1980s without needing anemulator, though an emulator likeDOSBox now has near-native functionality at full speed (and is necessary for certain games which may run too fast on modern processors). Additionally, many modern PCs can still run DOS directly, although special options such as USB legacy mode and SATA-to-PATA emulation may need to be set in the BIOS setup utility. Computers using theUEFI might need to be set at legacy BIOS mode to be able to boot DOS. However, the BIOS/UEFI options in most mass-produced consumer-grade computers are very limited and cannot be configured to truly handle OSes such as the original variants of DOS.
The spread of thex86-64 architecture has further distanced current computers' and operating systems' internal similarity with the original IBM PC by introducing yet another processor mode with an instruction set modified for 64-bit addressing, but x86-64 capable processors also retain standard x86 compatibility.
Columbia Data Products (301-992- 3400) turns out another split-personality computer, appropriately named the Multi-Personal Computer. Using only the Intel 8088 microprocessor, it manifests its duality in an ability to run both I.B.M.-oriented software and software requiring an operating system called MP/M-86.