IBM PC compatible computers are those generally similar to the original IBM PC, XT, and AT. The IBM Personal Computer XT, often shortened to the IBM XT or simply XT, was IBM's successor to the original IBM PC. The IBM Personal Computer/AT, more commonly known as the IBM AT and also sometimes called the PC AT or PC/AT, was IBM 's second-generation Such computers used to be referred to as PC clones, or IBM clones since they almost exactly duplicated all the significant features of the PC, XT, or AT internal design, facilitated by various manufacturers' ability to legally reverse engineer the BIOS through cleanroom design. In Computing, the BIOS (ˈbaɪoʊs Clean room design (also known as the Chinese wall technique is the method of copying a design by Reverse engineering and then recreating it without infringing Columbia Data Products built the first clone of an IBM computer through a cleanroom implementation of its BIOS. Columbia Data Products (CDP introduced the MPC 1600 "Multi Personal Computer" in June 1982 Early IBM PC compatibles used the same computer bus as the original PC and AT models, which was later named the ISA Bus when manufacturers developed alternatives to the original IBM standard. In Computer architecture, a bus is a subsystem that transfers data between computer components inside a Computer or between computers Industry Standard Architecture (in practice almost always shortened to ISA) was a Computer bus standard for IBM compatible computers
The term "IBM compatible" became exclusively historical once IBM stopped manufacturing personal computers.
Descendants of the IBM PC compatibles make up the majority of microcomputers on the market today, although interoperability with the bus structure and peripherals of the original PC, XT or AT may be non-existent. microcomputer is a Computer with a Microprocessor as its Central processing unit.
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History
Origins
The origins of this platform came with the decision by IBM in 1980 to market a low-cost single-user computer that they dubbed a personal computer as quickly as possible in response to Apple Computer's success in the burgeoning market. In Computing, a platform describes some sort of Hardware architecture or Software framework (including Application frameworks, that allows A personal computer ( PC) is any Computer whose original sales price size and capabilities make it useful for individuals and which is intended to be operated Apple Inc, ( formerly Apple Computer Inc, is an American Multinational corporation with a focus on designing and manufacturing Consumer electronics On 12 August 1981, the first IBM PC went on sale. Events 1099 - First Crusade: Battle of Ascalon - Crusaders under the command of Godfrey of Bouillon defeat Fatimid Year 1981 ( MCMLXXXI) was a Common year starting on Thursday (link displays the 1981 There were three operating systems (OS) available for it but the most popular and least expensive was PC DOS, a version of MS DOS licensed from Microsoft. An operating system (commonly abbreviated OS and O/S) is the software component of a Computer system that is responsible for the management and coordination Microsoft Corporation is an American multinational Computer technology Corporation, which rose to dominate the Home computer In a crucial concession, IBM's agreement allowed Microsoft to sell its own version, MS-DOS, for non-IBM platforms. MS-DOS (short for M icro' s' oft D isk O perating S ystem is an Operating system commercialized by Microsoft. The only proprietary component of the PC was the BIOS (Basic Input/Output System). In Computing, the BIOS (ˈbaɪoʊs
A number of computers based on the 8086/8088 processors, but with different architecture to the PC, and which ran under their own versions of MS-DOS and CP/M-86, were manufactured during this period. However, software which addressed the hardware directly instead of making standard calls to MS-DOS was faster, although against the idea of using a customised operating system which matched standard software with diverse hardware; this was particularly relevant to games. The IBM PC was the only machine sold in high enough volumes to justify writing software specifically for it, and this encouraged other manufacturers to produce machines which could run the same programs and use the same expansion cards and peripherals as the PC. An expansion card (also expansion board, adapter card or accessory card) in Computing is a Printed circuit board that can be inserted The 808x computer marketplace rapidly excluded all machines which were not functionally very similar to the PC. The 640kB limit on "conventional" system memory available to MS-DOS is a legacy of that period; other non-clone machines did not have this limit.
The original "clones" of the IBM Personal Computer were created without IBM's participation or approval. Columbia closely modeled the IBM PC and produced the first "compatible" PC (i. Columbia Data Products (CDP introduced the MPC 1600 "Multi Personal Computer" in June 1982 e. , more or less compatible to the IBM PC standard) in June 1982 closely followed by Eagle Computer. Eagle Computer of Los Gatos California was an early microcomputer manufacturing company Compaq Computer Corp. announced its first IBM PC compatible a few months later in November 1982—the Compaq Portable. Compaq Computer Corporation was an American Personal computer company founded in 1982 and is now a brand name of Hewlett-Packard. The Compaq Portable was the first product in the Compaq portable series to be commercially available under the Compaq Computer Corporation brand. The Compaq was not only the first "sewing machine-sized" portable PC but, even more important, was the first essentially 100% PC-compatible computer. A portable computer is a Computer that is designed to be moved from one place to another The company could not directly copy the BIOS as a result of the court decision in Apple v. Franklin, but it could reverse-engineer the IBM BIOS and then write its own BIOS using clean room design. Apple Computer Inc v Franklin Computer Corp, 714 F2d 1240 ( 3d Cir Reverse engineering (RE is the process of discovering the technological principles of a device object or system through analysis of its structure function and operation Clean room design (also known as the Chinese wall technique is the method of copying a design by Reverse engineering and then recreating it without infringing Compaq became a very successful PC manufacturer, but was bought out by Hewlett-Packard in 2002.
Compatibility issues
- See also: Influence of the IBM-PC on the PC market
Simultaneously, many manufacturers such as Xerox, HP, Digital, Sanyo, Texas Instruments, Tulip and Wang introduced personal computers that were—although x86- and MS-DOS-based—not completely software- or hardware-compatible with the IBM PC. Xerox Corporation ( (name ˈziːrɒks is a global document management company which manufactures and sells a range of color and black-and-white printers, multifunction Digital Equipment Corporation was a pioneering American company in the Computer industry () is a major Japanese electronics company and member of the Fortune 500 whose headquarters is located in Moriguchi, Osaka prefecture, Japan Texas Instruments ( better known in the electronics industry (and popularly as TI, is an American company based in Dallas, Texas, USA Wang Laboratories was a computer company founded in 1951 by Dr While not providing total compatibility seems short-sighted in retrospect, it is not always appreciated just how fast the rise of the IBM clone market was, and the degree to which it took the industry by surprise.
Microsoft's intention, and the mindset of the industry from 1981 to as late as the mid-1980s, was that application writers would write to the application programming interfaces (APIs) in MS-DOS, and in some cases to the firmware BIOS, and that this level of interface would form what would now be called a hardware abstraction layer. A hardware abstraction layer ( HAL) is an Abstraction layer, implemented in software between the physical hardware of a Computer and Each computer would have its own Original Equipment Manufacturer (OEM) version of MS-DOS, customized to its hardware. An original equipment manufacturer, or OEM is typically a company that uses a component made by a second company in its own product or sells the product of the second company Any piece of software written for MS-DOS would run on any MS-DOS computer, regardless of variations in hardware design.
This expectation seemed reasonable in the context of the computer marketplace as it existed then. Until then Microsoft was primarily focused on computer languages such as BASIC. In Computer programming, BASIC (an Acronym for Beginner's All-purpose Symbolic Instruction Code) is a family of High-level programming languages The established small system operating software was CP/M from Digital Research, which was in use both at the hobbyist level and at the more professional end of the microcomputer spectrum. CP/M (Control Program for Microcomputers is an Operating system originally created for Intel 8080 / 85 based Microcomputers by Gary Kildall To achieve such widespread use, the OS had to operate across a range of machines from different vendors that had widely varying hardware, although most were based on the 8080 and Z-80 architectures, and 64k RAM quickly became standard. The Zilog Z80 is an 8-bit Microprocessor designed and sold by Zilog from July 1976 onwards Many CP/M-based computers came with a suite of software (often including MicroPro's WordStar, the CalcStar spreadsheet, simple DataStar database manager, and a version of the BASIC programming language interpreter). WordStar was a Word processor application published by MicroPro, originally written for the CP/M operating system but later ported to DOS, that Those customers who needed additional applications beyond the starter pack could expect publishers to offer their products in several media formats for a variety of computers. A starter pack (or starter deck) is a sealed package of cards or figurines designed to serve as the beginning of a collection in collectible card games and
Microsoft's competing OS was initially targeted to run on a similar varied spectrum of hardware, although all based on the 8086 architecture. Thus, MS-DOS was for many 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 the trade dress of the given PC vendor; the different versions were in general incompatible with different hardware. Trade dress refers to characteristics of the visual appearance of a product or its packaging (or even the facade of a building such as a restaurant that may be registered and protected Bugs were to be reported to the OEM, not to Microsoft. However, as clones 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 support for character-oriented applications such as those that could have been implemented on a minicomputer and a text-only terminal. A computer terminal is an electronic or electromechanical hardware device that is used for entering data into and displaying data from a Computer or a Computing Had the bulk of commercially important software fallen within these bounds, 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 very quickly evolved beyond the simple terminal applications that MS-DOS supported directly. Spreadsheets, WYSIWYG word processors, presentation software and remote communication software established new markets that exploited the PC's strengths, but required capabilities beyond what MS-DOS interfaces provided. A spreadsheet is a Computer application that simulates a paper worksheet WYSIWYG (ˈwɪziwɪg or /ˈwɪzɪwɪg/ is an Acronym for W hat Y ou S ee I s W hat Y ou G A presentation program is a Computer software package used to display information normally in the form of a Slide show. Communication software is used to provide remote access to systems and exchange files and real-time messages in text audio and/or video formats between different computers or user IDs Thus, from very early in the development of the MS-DOS software environment, many significant pieces of popular commercial software wrote directly to the hardware, for a variety of reasons:
- MS-DOS itself did not provide any way to position the text cursor (except to advance it after printing each letter). While the BIOS video interface routines were adequate for rudimentary output, they were inefficient due to not having "string" output (only output by individual character) and the insertion of delay periods to compensate for CGA hardware "snow" (a display artifact of CGA cards produced when writing directly to screen memory). A program that wrote directly to video memory could achieve output rates 5 to 20 times faster than making standard calls to the BIOS and MS-DOS.
- Graphics capability was not taken seriously in the original IBM design brief; it was considered to be an exotic or novelty function. Computer graphics are Graphics created by Computers and more generally the Representation and Manipulation of Pictorial Data MS-DOS did not have an API for graphics, and the BIOS only included the most rudimentary of graphics functions (such as changing screen modes and plotting single points); having to make a BIOS call for every point drawn or modified also increased overhead considerably, making the BIOS interface notoriously slow. Because of this, line-drawing, arc-drawing, and blitting had to be performed by the application to achieve acceptable speed, which was usually done by bypassing the BIOS and accessing video memory directly. A line drawing algorithm is a graphical Algorithm for approximating a line segment on discrete graphical media Bit blit ( bitblt, blitting etc is a Computer graphics operation in which several Bitmap patterns are combined into one using a "raster
- Games, even early ones, mostly required a true graphics mode. They also performed any machine-dependent trick the programmers could think of in order to gain speed. Though initially the major market for the PC was for business applications, games capability became an important factor in driving PC purchases as PC prices fell.
- Communications software directly accessed the UART chip, because the MS-DOS API and the BIOS did not provide full support for the chip's capabilities and was far too slow to keep up with hardware which could transfer data at 19200 baud. A universal asynchronous receiver/transmitter (usually abbreviated UART and ˈjuːɑrt is a type of "asynchronous receiver/transmitter" a piece of Computer
- Even for standard business applications, speed of execution was a significant competitive advantage. This was shown dramatically by Lotus 1-2-3's competitive knockout of rival Context MBA in the then-popular genre of integrated software. Lotus 1-2-3 is a Spreadsheet program from Lotus Software (now part of IBM) Context MBA was the first Integrated software application for personal computers providing five functions in one program Spreadsheet, Database, Charting Integrated software is software for Personal computers that combines the most commonly used functions of many productivity software programs into one application Context MBA, now almost forgotten, preceded Lotus to market and included more functions; it was written in standard Pascal, making it highly portable but, given the compilers of the day, too slow to be truly usable on a PC. Pascal is an influential imperative and procedural Programming language, designed in 1968/9 and published in 1970 by Niklaus Wirth as a small Lotus was written in pure assembly language and performed some machine-dependent tricks. It was so much faster that Context MBA was dead as soon as Lotus arrived.
- Disk copy-protection schemes, in common use at the time, worked by reading nonstandard data patterns on the diskette to verify originality. Copy protection, also known as content protection, copy prevention, or copy restriction, is a technology for preventing the unauthorised reproduction These patterns were difficult or impossible to detect using standard DOS or BIOS calls, so direct access to the disk controller hardware was necessary for the protection to work.
At first, few "compatibles" other than Compaq's models offered compatibility beyond the DOS/BIOS level. The Amiga is a family of Personal computers originally developed by Amiga Corporation. Reviewers and users developed suites of programs to test compatibility; the ability to run Lotus 1-2-3 or Microsoft Flight Simulator became one of the most significant "stress tests". Microsoft Flight Simulator (sometimes abbreviated to MSFS or FS) is a Flight simulator program for Microsoft Vendors gradually learned not only how to emulate the IBM BIOS but also where to use identical hardware chips to perform key functions within the system. Eventually, the Phoenix BIOS and similar commercially-available products permitted computer makers to build essentially 100%-compatible clones without having to reverse-engineer the IBM PC BIOS themselves. Phoenix Technologies Ltd ( is a creator of computer BIOS software
Over time, IBM damaged its own market by itself failing to appreciate the importance of "IBM compatibility", introducing products such as the IBM Portable (which was outperformed and outsold by the Compaq Portable launched at the same time) and the PCjr, which had significant incompatibilities with the original PC. The IBM Portable Personal Computer 5155 model 68 was an early Portable computer developed by IBM after the success The Compaq Portable was the first product in the Compaq portable series to be commercially available under the Compaq Computer Corporation brand. The IBM PCjr (read "PC junior" was IBM 's first attempt to enter the market for relatively inexpensive Educational and home-use personal By the mid to late 1980s buyers began to regard PCs as commodity items, and doubted that the security blanket of the IBM name warranted the price difference. A security blanket is any familiar object whose presence provides comfort or security to its owner such as the literal Blankets often favoured by small children Meanwhile, MS-DOS-compatible (but not hardware-compatible) systems did not succeed in the marketplace. The inability to run the off-the-shelf high-performance software packages that the IBM PC and true compatibles did resulted in poor sales and the eventual extinction of that category of systems.
The declining influence of IBM
Since 1981, IBM PC compatibles have grown to dominate both the home and business markets of commodity computers, with the only notable alternative architecture being the Apple Macintosh computers (which comprise around 4% of shipping computers). A business (also called firm or an enterprise) is a legally recognized organizational entity designed to provide goods and/or services to Macintosh, commonly nicknamed Mac is a Brand name which covers several lines of Personal computers designed developed and marketed by Apple Inc However, IBM itself lost the leadership role in the market for IBM PC compatibles by 1990. Three events in retrospect are likely turning points:
- Compaq beating IBM to the market in 1986 with the first 80386-based PC.
- IBM's 1987 introduction of incompatible technologies, such as its proprietary MicroChannel Architecture (MCA) computer bus, in its PS/2 line. Micro Channel Architecture (in practice almost always shortened to MCA) was a proprietary 16- or 32-bit parallel Computer bus In Computer architecture, a bus is a subsystem that transfers data between computer components inside a Computer or between computers The Personal System/2 or PS/2 was IBM 's third generation of Personal computers The PS/2 line released to the public in 1987 was created by IBM in an
- The 1988 introduction by the "Gang of Nine" companies of a rival Extended Industry Standard Architecture (EISA) bus aimed at toppling, rather than copying, MCA. The Gang of Nine was a group of IBM competitors who came together in 1988 to create the Extended Industry Standard Architecture (EISA bus to compete with IBM's The Extended Industry Standard Architecture (in practice almost always shortened to EISA and frequently pronounced "eee-suh" is a bus standard for IBM compatible
- The duelling Expanded memory and Extended memory standards of the late 1980s, both developed with no input from IBM. In computing expanded memory (commonly known as EMS memory) is a system of Bank switching introduced around 1984 that provided additional memory to MS-DOS In computing Extended memory refers to memory above the first Megabyte of Address space in an IBM PC with an 80286 or later
However, as the market evolved, IBM derived a considerable income stream from license fees from companies who paid for licenses to use IBM patents that were in the PC design, to the extent that IBM's focus changed from discouraging PC clones to maximizing its revenue from license sales. IBM finally relinquished its role as a PC manufacturer in April 2005, when it sold its PC Division to Lenovo for $1. Lenovo Group Limited (,) is China's largest and the world's fourth largest Personal computer manufacturer after Hewlett-Packard and Dell of the U 75 billion.
As of October 2007, Hewlett-Packard and Dell hold the largest shares of the PC market in North America. The multinational technology company Dell Inc develops manufactures sells and supports Personal computers and other computer-related products They are also successful overseas, with Acer, Lenovo, and Toshiba also notable. Acer Incorporated ( ( is a Taiwanese multinational electronics manufacturer Lenovo Group Limited (,) is China's largest and the world's fourth largest Personal computer manufacturer after Hewlett-Packard and Dell of the U ( is a multinational conglomerate manufacturing company headquartered in Tokyo, Japan. Worldwide, a huge number of PCs are "white box" systems assembled by a myriad of local systems builders. In Computer hardware, a white box is a Personal computer or server assembled from off-the-shelf parts Despite advances in computer technology, all current IBM PC compatibles remain very much compatible with the original IBM PC computers, although most of the components implement the compatibility in special backward compatibility modes used only during a system boot. Technology is a broad concept that deals with a Species ' usage and knowledge of Tools and Crafts and how it affects a species' ability to control and adapt In Technology, especially Computing (irrespective of platform a product is said to be backward compatible when it is able to take the place of an older product A computer is a Machine that manipulates data according to a list of instructions. In Computing, booting ( booting up) is a bootstrapping process that starts Operating systems when the user turns on a Computer system
Expandability
One of the strengths of the PC compatible platform is its modular hardware design. End-users could readily upgrade peripherals and to some degree, processor and memory without modifying the computer's motherboard or replacing the whole computer, as was the case with many of the microcomputers of the time. A motherboard is the central or primary Printed circuit board (PCB making up a complex electronic system such as a modern Computer or Laptop microcomputer is a Computer with a Microprocessor as its Central processing unit. 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 the IBM 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 licence payments to IBM both for the PS/2 bus and any prior AT-bus designs produced by the company seeking a license. The Personal System/2 or PS/2 was IBM 's third generation of Personal computers The PS/2 line released to the public in 1987 was created by IBM in an 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 the PC compatible platform advanced much faster than other competing platforms of the time, even if only because of its market dominance.
"IBM PC Compatible" becomes "Wintel"
In the 1990s, IBM's influence on PC architecture became increasingly irrelevant. Instead of focusing on staying compatible with the IBM PC, vendors began to focus on compatibility with the evolution of Microsoft Windows. Microsoft Windows is a series of Software Operating systems and Graphical user interfaces produced by Microsoft. In 1993, a version of Windows NT was released that could run on processors other than x86. Windows NT is a family of Operating systems produced by Microsoft, the first version of which was released in July 1993 See also X86 assembly language The generic term x86 refers to the most commercially successful Instruction set architecture in the history of Personal (It did require a recompile, however, and many applications weren't recompiled. ) Still, its hardware independence was taken advantage of by SGI x86 workstations - thanks to NT's HAL, NT (and more importantly, its applications) could run on them. Silicon Graphics Inc (commonly initialised to SGI, historically sometimes referred to as Silicon Graphics Computer Systems or SGCS) is a company A hardware abstraction layer ( HAL) is an Abstraction layer, implemented in software between the physical hardware of a Computer and No mass-market personal computer hardware vendor dares to be incompatible with the latest version of Windows, and Microsoft's annual WinHEC conferences provide a setting in which Microsoft can lobby for and --- in some cases --- dictate the pace and direction of the hardware side of the PC industry. The Windows Hardware Engineering Conference (WinHEC is the annual Software and hardware developer -oriented Trade show and Business conference where Hardware is a general term that refers to the physical artifacts of a Technology. Microsoft and Windows have become so important to the ongoing development of the PC hardware that industry writers have taken to using the term "Wintel architecture" ("Wintel" being a portmanteau of "Windows" and "Intel") to refer to the combined hardware-software platform. Wintel (Now often referred to as "PC" is a term used to describe desktop Computers and servers of the type commonly used in homes and businesses since This terminology itself is becoming a misnomer though as Intel has lost absolute control of the direction of the development of this hardware platform as AMD has become a major player and in some aspects a leader, with Intel starting to copy AMD technologies such as x86-64. x86-64 is a Superset of the x86 instruction set architecture.
Design limitations and more compatibility issues
Although the IBM PC was designed for expandability, the designers could not anticipate the hardware developments of the '80s. To make things worse, IBM's choice of the Intel 8088 for the CPU introduced several limitations which were hurdles for developing software for the PC compatible platform. The Intel 8088 is an Intel X86 Microprocessor based on the 8086, with 16- Bit registers and an 8-bit external Data bus For example, the 8088 processor only had a 20-bit memory addressing space. In Computing, an address space defines a range of discrete addresses each of which may correspond to a physical or virtual Memory register, a network host In order to expand PCs beyond one megabyte, Lotus, Intel, and Microsoft jointly created expanded memory (EMS), a bank-switching scheme to allow access to additional memory provided by add-in hardware, available via a 64 KB "window" inside the 20-bit addressing. In computing expanded memory (commonly known as EMS memory) is a system of Bank switching introduced around 1984 that provided additional memory to MS-DOS Later, Intel CPUs had larger address spaces and could directly address 16 MB (80286) or more, leading Microsoft to additionally develop extended memory (XMS) which did not require additional hardware. In computing Extended memory refers to memory above the first Megabyte of Address space in an IBM PC with an 80286 or later Expanded and extended memory have incompatible interfaces, so anyone writing software that used more than one megabyte had to support both systems for the most compatibility. A protected mode OS can also be written for the 80286, but DOS application compatibility was harder than expected, owing not only to the fact that most DOS application directly access the hardware, but also that most BIOS interrupts were in reserved interrupt vectors. In computing protected mode, also called protected virtual address mode, is an operational mode of X86 -compatible Central processing units (CPU The Intel 286, introduced on February 1, 1982, (originally named 80286, and also called iAPX 286 in the programmer's manual
Graphics cards suffered from their own incompatibilities. A video card, also known as a graphics accelerator card, display adapter, or graphics card, is a hardware component whose function is to Once graphics cards advanced to SVGA level, the standard for accessing them was no longer clear. Super Video Graphics Array or Ultra Video Graphics Array, almost always abbreviated to Super VGA, Ultra VGA or just SVGA or UVGA is At the time, PC programming involved using a memory model that had 64 KB memory segments. x86 memory segmentation refers to the implementation of Memory segmentation on the X86 architecture. The most common VGA graphics mode's screen memory fitted into a single memory segment. The term Video Graphics Array ( VGA) refers specifically to the display hardware first introduced with the IBM PS/2 line of computers in 1987, but through its widespread SVGA modes required more memory, so accessing the full screen memory was tricky. Each manufacturer developed their own ways of accessing the screen memory, even going so far as not to number the modes consistently. An attempt at creating a standard called VBE was made, but not all manufacturers adhered to it. VESA BIOS Extensions ( VBE) comprise a VESA standard currently at version 3 that defines the interface that can be used by software to access compliant video boards
Due to the wide number of third-party adapters for the PC and no standard for interfacing with them, programming the PC could be difficult. When developing for the PC, a large test-suite of various hardware combinations was needed to make sure the software was compatible with as many PC configurations as possible. Even the PC itself had no clear application interface to the flat memory model the 386 and higher could provide in protected mode. Again a protected mode OS could be written for the 80386. In computing protected mode, also called protected virtual address mode, is an operational mode of X86 -compatible Central processing units (CPU This time, DOS compatibility was much easier because of virtual 8086 mode. In the 80386 Microprocessor and later Virtual 8086 mode, also called virtual real mode or VM86, allows the execution of Real mode Unfortunately programs cannot switch directly to protected mode from that mode, so eventually, some new memory-model APIs were developed, VCPI and DPMI, the latter becoming the most popular. In computing the DOS Protected Mode Interface (DPMI is a specification introduced in 1989 which allows a DOS program to run in Protected mode, granting access to In computing the DOS Protected Mode Interface (DPMI is a specification introduced in 1989 which allows a DOS program to run in Protected mode, granting access to
Meanwhile, consumers were overwhelmed by the many different combinations of hardware on offer. To give the consumer some idea of what sort of PC would be needed to run a given piece of software, the Multimedia PC (MPC) standard was set in 1990. The Multimedia PC, or MPC, was a recommended configuration for a PC with a CD-ROM drive It meant that a PC that met the minimum MPC standard could be considered an MPC. Software that could run on a minimalistic MPC-compliant PC would be guaranteed to run on any MPC. The MPC level 2 and MPC level 3 standards were later set, but the term "MPC compliant" never caught on. After MPC level 3 in 1996, no further MPC standards were established.
Challenges to Wintel domination
The success of Microsoft Windows had driven nearly all other rival commercial operating systems into near-extinction, and had ensured that the “IBM-compatible” PC was the dominant computing platform. An operating system (commonly abbreviated OS and O/S) is the software component of a Computer system that is responsible for the management and coordination In Computing, a platform describes some sort of Hardware architecture or Software framework (including Application frameworks, that allows This meant that if a manufacturer only made their software for the Wintel platform, they would be able to reach out to the vast majority of computer users. Wintel (Now often referred to as "PC" is a term used to describe desktop Computers and servers of the type commonly used in homes and businesses since By the late 1980s, the only major competitor to Windows with more than a few percentage points of market share was the Apple Macintosh platform. Market share, in Strategic management and Marketing, is the percentage or proportion of the total available Market or Market segment that is Macintosh, commonly nicknamed Mac is a Brand name which covers several lines of Personal computers designed developed and marketed by Apple Inc The Mac started out billed as "the computer for the rest of us" but the DOS/Windows/Intel onslaught quickly drove the Macintosh into an education and desktop publishing niche, from which it has only recently begun to emerge. Desktop publishing (also known as DTP) combines a Personal computer and WYSIWYG page layout Software to create Publication Documents By the mid to late 1990s Mac marketshare 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 marketplace (BeOS and OS/2 for example). BeOS is an Operating system for Personal computers which began development by Be Inc OS/2 is a computer Operating system, initially created by Microsoft and IBM, then later developed by IBM exclusively
On the hardware front, Intel initially licensed their technology so that other manufacturers could make x86 CPUs. See also X86 assembly language The generic term x86 refers to the most commercially successful Instruction set architecture in the history of Personal As the "Wintel" platform gained dominance Intel abandoned this practice. Companies such as AMD and Cyrix developed alternative CPUs that were functionally compatible with Intel's. Cyrix was a CPU manufacturer that began in 1978 in Richardson Texas as a specialist supplier of high-performance math co-processors for 286 and 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 evolution of the 'x86 platform when its Athlon line of processors continued to develop the classic x86 architecture as Intel deviated with its "Netburst" architecture for the Pentium 4 CPUs and the IA-64 architecture for the Itanium line of server CPUs. AMD developed the first 64 bit extension of the x86 architecture that forced intel to make a clean-room version of it, in all its latest CPUs. In 2006 Intel began abandoning Netburst with the release of their line of "Core" processors that represented an evolution of the earlier Pentium III.
The PC today
The term 'IBM PC compatible' is not commonly used for current computers. The competing, non-compatible platforms have either died off, been relegated to niche, enthusiast markets like the Amiga or, like Mac OS and Linux, have evolved compatibility features easing interoperability and data exchange. The Amiga is a family of Personal computers originally developed by Amiga Corporation. Mac OS is the trademarked name for a series of Graphical user interface -based Operating systems developed by Apple Inc Linux (commonly pronounced ˈlɪnəks The processor speed and memory capacity of modern PCs are many orders of magnitude greater than they were on the original IBM PC and yet backwards compatibility has been maintained. An order of magnitude is the class of scale or magnitude of any amount where each class contains values of a fixed ratio to the class preceding it A modern PC can still run many of the simpler programs written for the PCs of the early 1980s without needing an emulator. An emulator duplicates (provides an emulation of the functions of one System using a different system so that the second system behaves like (and appears to
See also
- Computer hardware
- Computer software
- Computer platform
- IBM PC
- Personal computer
- Homebuilt computer
- History of computing hardware (1960s-present)
- List of early non-IBM-PC-compatible PCs
- PC speaker
- AT form factor
- x86 architecture