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Encyclopedia > IBM PC compatible

IBM PC compatible computers are those generally similar to the original IBM PC, XT, and AT. 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. Columbia Data Products built the first clone of an IBM computer through a cleanroom implementation of its BIOS. IBM PC (IBM 5150) with keyboard and green screen monochrome monitor (IBM 5151), running MS-DOS 5. ... The IBM Personal Computer XT, often shortened to the PC XT or simply XT, was IBMs successor to the original IBM PC. It was released as IBM product number 5160 on March 8, 1983, and was one of the first computers to come standard with a hard drive. ... The IBM Personal Computer/AT, more commonly known as the IBM AT and also sometimes called the PC AT or PC/AT, was IBMs second-generation PC, designed around the 6 MHz Intel 80286 microprocessor and released in 1984 as model number 5170. ... For other uses, see Bios. ... For the manufacturing process setting, used for example in integrated circuit manufacture, see Clean room. ...


"IBM compatible" is now a historical term since IBM no longer manufactures 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. The Commodore 64 was one of the most popular microcomputers of its era, and is the best selling model of home computer of all time. ...

Contents

History

Origins

The original IBM PC (Model 5150) motivated the production of clones in the early-1980s.
The original IBM PC (Model 5150) motivated the production of clones in the early-1980s.

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. On 12 August 1981, the first IBM PC went on sale. 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. In a crucial concession, IBM's agreement allowed Microsoft to sell its own version, MS-DOS, for non-IBM platforms. The only proprietary component of the PC was the BIOS (Basic Input/Output System). Download high resolution version (1024x740, 91 KB) IBM PC 5150 with keyboard and green monochrome monitor (5151), running MS-DOS 5. ... Download high resolution version (1024x740, 91 KB) IBM PC 5150 with keyboard and green monochrome monitor (5151), running MS-DOS 5. ... IBM PC (IBM 5150) with keyboard and green screen monochrome monitor (IBM 5151), running MS-DOS 5. ... In computing, a platform describes some sort of framework, either in hardware or software, which allows software to run. ... Year 1980 (MCMLXXX) was a leap year starting on Tuesday (link displays the 1980 Gregorian calendar). ... Apple Inc. ... is the 224th day of the year (225th in leap years) in the Gregorian calendar. ... Year 1981 (MCMLXXXI) was a common year starting on Thursday (link displays the 1981 Gregorian calendar). ... IBM PC (IBM 5150) with keyboard and green screen monochrome monitor (IBM 5151), running MS-DOS 5. ... An operating system (OS) is the software that manages the sharing of the resources of a computer and provides programmers with an interface used to access those resources. ... Microsoft Corporation, (NASDAQ: MSFT, HKSE: 4338) is a multinational computer technology corporation with global annual revenue of US$44. ... Microsofts disk operating system, MS-DOS, was Microsofts implementation of DOS, which was the first popular operating system for the IBM PC, and until recently, was widely used on the PC compatible platform. ... For other uses, see Bios. ...


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.e., more or less compatible to the IBM PC standard) in June 1982 closely followed by Eagle Computer. Compaq Computer Corp. announced its first IBM PC compatible a few months later in November 1982—the Compaq Portable. The Compaq was not only the first "sewing machine-sized" portable PC but, even more important, was the first essentially 100% PC-compatible computer. 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. Compaq became a very successful PC manufacturer, but was bought out by Hewlett-Packard in 2002. Year 1982 (MCMLXXXII) was a common year starting on Friday (link displays the 1982 Gregorian calendar). ... Eagle Computer was one of the first manufacturers of clones of the IBM PC. Eagle was started in 1983 by Dennis Barnhart. ... Compaq Computer Corporation is an American personal computer company founded in 1982, and now a brand name of Hewlett-Packard. ... Year 1982 (MCMLXXXII) was a common year starting on Friday (link displays the 1982 Gregorian calendar). ... The Compaq Portable was the first midget in the Compaq portable series to be brought out by Compaq Computer Corporation. ... A Portable computer is a computer that is designed to be moved from one place to another (in other words, it is a computer that is portable). ... Apple Computer, Inc. ... Reverse engineering (RE) is the process of taking something (a device, an electrical component, a software program, etc. ... For the meaning of Cleanroom engineering in software development, see Cleanroom Software Engineering. ... The Hewlett-Packard Company (NYSE: HPQ), commonly known as HP, is a very large, global company headquartered in Palo Alto, California, United States. ... Also see: 2002 (number). ...


Compatibility issues

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 hardware-compatible with the IBM PC. While such decisions seem foolish 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. Xerox Corporation (NYSE: XRX) (name pronounced ) is a global document management company, which manufactures and sells a range of color and black-and-white printers, multifunction systems, photo copiers, digital production printing presses, and related consulting services and supplies. ... The Rainbow 100 was a microcomputer introduced by Digital Equipment Corporation (DEC) in 1982 to compete in the IBM PC market. ... Sanyo Electric Co. ... Texas Instruments (NYSE: TXN), better known in the electronics industry (and popularly) as TI, is an American company based in Dallas, Texas, USA, renowned for developing and commercializing semiconductor and computer technology. ... Tulip Computers NV (Euronext: TULIP) is a Dutch computer manufacturer that manufactures PC clones. ... Wang logo circa 1976. ...


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 (or APIs) in MS-DOS, and in some cases to the firmware BIOS, and that these components would form what would now be called a hardware abstraction layer. Each computer would have its own Original Equipment Manufacturer (OEM) version of MS-DOS, customized to its hardware. Any piece of software written for MS-DOS would run on any MS-DOS computer, regardless of variations in hardware design. Year 1981 (MCMLXXXI) was a common year starting on Thursday (link displays the 1981 Gregorian calendar). ... The 1980s refers to the years from 1980 to 1989. ... API and Api redirect here. ... A hardware abstraction layer (HAL) is an abstraction layer, implemented in software, between the physical hardware of a computer and the software that runs on that computer. ... Original equipment manufacturer, or OEM, is a term that refers to containment-based re-branding, namely where one company uses a component of another company within its product, or sells the product of another company under its own brand. ...


This expectation seemed reasonable, in the light of the computer marketplace as it existed then. At that time, Microsoft was primarily focused on computer languages such as BASIC. The established model for 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. To achieve this spectrum of use, the OS had to operate across a range of machines that had widely varying hardware, although mostly based on the 8080 and Z-80 architectures. Many CP/M-based computers came with a suite of software (often including MicroPro's WordStar, CalcStar, and DataStar). 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. This article is about the programming language. ... CP/M is an operating system originally created for Intel 8080/85 based microcomputers by Gary Kildall of Digital Research, Inc. ... The Zilog Z80 is an 8-bit microprocessor designed and manufactured by Zilog from 1976 onwards. ... WordStar was a word processor application, published by MicroPro, originally written for the CP/M operating system but later ported to DOS, that enjoyed a dominant market share during the early to mid-1980s. ... In collectible card games and collectible miniature wargames, a starter pack (or starter deck) is a sealed package of cards or figurines, designed to serve as the beginning of a collection. ...


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 the manual's cover had the corporate color and logo of the PC vendor. Bugs were to be reported to the OEM, not to Microsoft. However, in the case of the clones, 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 Digital VT100 terminal. Had the bulk of commercially important software fallen within these bounds, hardware compatibility might not have mattered. However, very early in the development of the PC, its applications 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 provided. 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: The VT100 was a video terminal made by Digital Equipment Corporation (DEC) which became the de facto standard used by terminal emulators. ... Screenshot of a spreadsheet under OpenOffice A spreadsheet is a rectangular table (or grid) of information, often financial information. ... WYSIWYG (IPA Pronunciation [] or []), is an acronym for What You See Is What You Get, used in computing to describe a system in which content during editing appears very similar to the final product. ... A word processor (also more formally known as a document preparation system) is a computer application used for the production (including composition, editing, formatting, and possibly printing) of any sort of viewable or printed material. ... A presentation using PowerPoint. ... Wikipedia does not have an article with this exact name. ...

  • 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.
  • Graphics capability was not taken seriously in the original IBM design brief. It was considered to be an exotic or novelty function. MS-DOS didn't 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; this was usually done by bypassing the BIOS and accessing video memory directly.
  • 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.
  • 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.[1] The latter, now almost forgotten, preceded Lotus to market, included more functions, was written in Pascal, and was highly portable. It was also too slow to be really usable on a PC. 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, popular at the time, worked by reading nonstandard data patterns on the diskette to verify originality. 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, other than Compaq's models, few "compatibles" really lived up to their claim. "95% compatibility" was seen as excellent. Reviewers and users developed suites of programs to test compatibility, generally including Lotus 1-2-3 and Microsoft Flight Simulator, the two most popular "stress tests." Gradually vendors discovered not only how to emulate the IBM BIOS, but the places where they needed 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. A UART or universal asynchronous receiver-transmitter is a piece of computer hardware that translates between parallel bits of data and serial bits. ... A line drawing algorithm is a graphical algorithm for approximating a line segment on discrete graphical media. ... Bit blit (bitblt, blitting etc. ... Lotus 1-2-3 is a spreadsheet program from Lotus Software (now part of IBM). ... Pascal is an imperative computer programming language, developed in 1970 by Niklaus Wirth as a language particularly suitable for structured programming. ... Microsoft Flight Simulator is a flight simulator program for Microsoft Windows, marketed and often seen as a video game. ... Stress testing is a form of testing that is used to determine the stability of a given system or entity. ... Phoenix Technologies Ltd (NASDAQ: PTEC) is a creator of computer BIOS software. ...


Meanwhile, IBM damaged its own franchise by failing to appreciate the importance of "IBM compatibility", when they introduced products such as the IBM Portable (which was outperformed by the Compaq Portable launched at the same time, which went on to become the market leader), and later the PCjr, which had significant incompatibilities with the mainline PCs. By the mid-to-late 1980s, buyers began to regard PCs as commodity items, and became skeptical as to whether the security blanket of the IBM name warranted the price differential. Meanwhile, the incompatible Xeroxes and Digitals and Wangs did not succeed in the marketplace. Although they ran MS-DOS, the inability to run off-the-shelf software written for the IBM PC and true compatibles resulted in poor sales. The IBM Portable was an early portable computer developed by IBM after the success of Compaqs suitcase-size portable machine (the Compaq Portable). ... The Compaq Portable was the first midget in the Compaq portable series to be brought out by Compaq Computer Corporation. ... The IBM PCjr was a relatively inexpensive home computer of the 1980s, and it was IBMs first attempt to enter the educational and home computer markets. ... A security blanket is any familiar object whose presence provides comfort or security to its owner, such as the literal blankets often favored by small children. ...


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 PCs). However, IBM itself lost the leadership role in the market for IBM PC compatibles by 1990. Three events in retrospect are likely turning points: In economics, a business is a legally-recognized organizational entity existing within an economically free country designed to sell goods and/or services to consumers, usually in an effort to generate profit. ... The first Macintosh computer, introduced in 1984, upgraded to a 512K Fat Mac. The Macintosh or Mac, is a line of personal computers designed, developed, manufactured, and marketed by Apple Computer. ...

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 $1.75 billion. The Intel 80386 is a microprocessor which was used as the central processing unit (CPU) of many personal computers from 1986 until 1994 and later. ... Micro Channel architecture (in practice almost always shortened to MCA) was a proprietary 16 or 32-bit parallel computer bus created by IBM in the 1980s for use on their new PS/2 computers. ... In computer architecture, a bus is a subsystem that transfers data or power between computer components inside a computer or between computers and typically is controlled by device driver software. ... The Personal System/2 or PS/2 was IBMs second generation of personal computers. ... The Gang of Nine was a group of IBM competitors who came together in 1988 to build the EISA architecture, to compete with IBMs MCA. These companies were AST Research, Compaq Computer, Epson, Hewlett-Packard, NEC, Olivetti, Tandy, WYSE, and Zenith Data Systems. ... This article does not cite any references or sources. ... Lenovo Group Limited, formerly known as Legend Group Limited, is the largest personal computer manufacturer in the Peoples Republic of China, and as of 2004 is the eighth largest in the world. ...


As of October 2007, Hewlett-Packard and Dell hold the largest shares of the PC market in North America. They are also successful overseas, with Acer, Lenovo, and Toshiba also notable. Worldwide, a huge number of PCs are "white box" systems assembled by a myriad of local systems builders. 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. The Hewlett-Packard Company (NYSE: HPQ), commonly known as HP, is a very large, global company headquartered in Palo Alto, California, United States. ... Dell, Inc. ... Acer (LSE: ACID) (Traditional Chinese: ) is a Taiwanese multinational electronics manufacturer. ... Lenovo Group Limited, formerly known as Legend Group Limited, is the largest personal computer manufacturer in the Peoples Republic of China, and as of 2004 is the eighth largest in the world. ... Toshiba Corporations headquarters (Center) in Hamamatsucho, Tokyo Toshiba Corporation sales by division for year ending March 31, 2005 Toshiba Corporation ) (TYO: 6502 ) is a Japanese multinational conglomerate manufacturing company, headquartered in Tokyo, Japan. ... In computer hardware, a white box is a personal computer assembled from off-the-shelf parts. ... By the mid 20th century humans had achieved a mastery of technology sufficient to leave the surface of the Earth for the first time and explore space. ... This article or section does not cite its references or sources. ... This article or section is in need of attention from an expert on the subject. ... 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. This meant that if a component became obsolete, only an individual component had to be upgraded and not the whole computer as was the case with many of the microcomputers of the time. As long as applications used operating system calls and did not write to the hardware directly, the existing applications would work. However, MS-DOS (the dominant operating system of the time) did not have support for many calls for multimedia-hardware, and the BIOS was also inadequate. 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. The Commodore 64 was one of the most popular microcomputers of its era, and is the best selling model of home computer of all time. ...


"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. In 1993, Windows NT was released that in fact could run on processors other than x86. It did require a recompile, however, and many applications weren't recompiled. Still, its hardware independence was taken advantage of when the SGI x86 workstations were released that were not PC compatible. Thanks to NT's HAL, NT and more importantly, its applications could run on them. Windows 2000 was also released for them (support is right on the Windows 2000 CD, minus some drivers). No vendor dares to be incompatible with the latest version of Windows, and Microsoft's annual WinHEC conferences provides 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. 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 combination of "Windows" and "Intel") to refer to the combined hardware-software platform. 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. “Windows” redirects here. ... Windows NT (New Technology) is a family of operating systems produced by Microsoft, the first version of which was released in July 1993. ... Intel Pentium 4 (Northwood version), one example out of a huge number of x86 implementations from Intel, AMD, and others. ... Silicon Graphics, Inc. ... A hardware abstraction layer (HAL) is an abstraction layer, implemented in software, between the physical hardware of a computer and the software that runs on that computer. ... Windows 2000 (also referred to as Win2K) is a preemptive, interruptible, graphical and business-oriented operating system that was designed to work with either uniprocessor or symmetric multi-processor 32-bit Intel x86 computers. ... The Windows Hardware Engineering Conference (WinHEC) is the annual conference where Microsoft sets out its hardware plans for Microsoft Windows-compatible PCs. ... For other uses, see Hardware (disambiguation). ... Wintel is a term used to describe desktop computers and servers of the type commonly used in homes and businesses since the late 1980s (these are PC compatible computers running a version of Microsoft Windows). ... A portmanteau (IPA: ) is a word or morpheme that fuses two or more words or word parts to give a combined or loaded meaning. ... Advanced Micro Devices, Inc. ... The AMD64 or x86-64 is a 64-bit processor architecture invented by AMD. It is a superset of the x86 architecture, which it natively supports. ...


Entertainment software

The original IBM PC was not designed with games as its primary focus. Although color graphics adapters and joystick adapters were available from the beginning, the more widely-adapted monochrome adapter and simple sound capabilities made it unsuitable for multimedia applications such as entertainment. It was also priced as a business computer (its primary design focus), well outside of the entertainment market, and thus home users purchased multimedia-oriented computers produced by Atari, Commodore, or Amiga that offered dozens of colors and near-CD-quality sound capabilities. This article is about a corporate game company. ... Commodore, the commonly used name for Commodore International, was an American electronics company based in West Chester, Pennsylvania which was a vital player in the home/personal computer field in the 1980s. ... This article is about the family of home computers. ...


The games that were available for the dawn of the PC used the real strength of the machine, 16-bit processing at a higher clock speed (4.77 megahertz), to overcome the lack of multimedia capabilities. One of the most impressive titles for the machine, available less than a year after launch, was Microsoft Flight Simulator. Although Flight Simulator was available for other platforms, it ran at a faster framerate and with more detail on the PC, albeit without the colors or music capabilities available on Commodore or Amiga machines. Microsoft Flight Simulator is a flight simulator program for Microsoft Windows, marketed and often seen as a video game. ...


As the technology of the PC advanced, more advanced games were developed. As early as 1988, VGA cards were available for PC clones. These offered 256-colour graphics out of a palette of 262,144. Also in 1988, sound cards such as the Adlib and Creative Music System (precursor to the Sound Blaster) were available. These developments brought the PC up to a sufficient level such that it could support arcade games ported to the platform equal to the quality of other home computers of the time. Another advantage was that many consumers opted to equip their PCs with a hard drive, while relatively few home computer platforms were so equipped. This allowed PC games to be more ambitious in their use of resources, and made playing games faster and more convenient. Video Graphics Array (VGA) is a computer display standard first marketed in 1987 by IBM. VGA belongs to a family of earlier IBM video standards and largely remains backward compatible with them. ... A palette, in computer graphics, is a designated subset of the total range of colors supported by a computer graphics system. ... AdLib, Inc. ... The Sound Blaster family of sound cards was for many years the de facto standard for audio on the IBM PC compatible system platform, before PC audio became commoditized, and backward-compatibility became less of a feature. ... The Sound Blaster logo The Sound Blaster family of sound cards was for many years the de facto standard for audio on the IBM PC compatible system platform, before PC audio became commoditized, and backward-compatibility became less of a feature. ...


By 1990, the PC had comparable hardware to competing entertainment platforms of the time, such as the Commodore Amiga, but was still was not taken "seriously" as a games machine. This could have been caused by the higher price, or that the hardware was very awkward to program for, and required the development of different drivers for all the multimedia hardware options available to the consumer. As before, the PC's main strength -- raw processing power -- was used as leverage, and this led to impressive 3D or pseudo-3D titles such as Wing Commander, Ultima Underworld, Stunts, Wolfenstein 3D and the subsequent Doom. Doom in particular had the most wide-spread success, with awareness crossing over into mainstream media. Amiga is the name of a range of home/personal computers using the Motorola 68000 processor family, whose development started in 1982. ... 3D computer graphics (in contrast to 2D computer graphics) are graphics that utilize a three-dimensional representation of geometric data that is stored in the computer for the purposes of performing calculations and rendering 2D images. ... Pseudo-3D is a term that means that something uses 2-d graphics to simulate three dimentional graphics. ... It has been suggested that this article or section be merged with Wing Commander (computer game). ... Ultima Underworld is a series of two computer role playing games published by Origin Systems in the early 1990s. ... This article is about the video game. ... Wolfenstein 3D (commonly abbreviated to Wolf 3D) is the computer game that started the first person shooter genre on the PC. It was created by id Software and published by Apogee Software on May 5, 1992. ... Doom (or DOOM)[1] is a 1993 computer game by id Software that is a landmark title in the first-person shooter genre. ...


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. One example was the DOS 640 KB barrier (memory below 640 KB is known as conventional memory). This was due to the 20-bit memory addressing space of the 8088. In order to expand PCs beyond one mebibyte, Lotus, Intel, and Microsoft jointly created expanded memory (EMS), a scheme to allow access to additional memory provided by add-in hardware, available via a 64 KB "window" inside the 20-bit addressing. 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. Expanded and extended memory have incompatible interfaces, so anyone writing software that used more than one mebibyte 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. The Intel 8088 is an Intel microprocessor based on the 8086, with 16-bit registers and an 8-bit external data bus. ... Conventional memory is the first 640 kibibytes of an IBM PCs memory. ... The abbreviation KB or kb can refer to: kilobyte (kB or KB), equal to 1,000 bytes or 1024 bytes depending on context, or kibibyte (KiB), equal to 1,024 bytes. ... Conventional memory is the first 640 kibibytes of an IBM PCs memory. ... 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, peripheral device, disk sector or other logical or physical entity. ... Expanded Memory was a trick invented around 1984 that provided more memory to byte-hungry, business-oriented MS-DOS programs. ... MB, Mb, mB or mb may mean: Mb (digraph) Megabit (1,000,000 bits) or mebibit (220 = 1,048,576 bits); the preferred symbols are Mb and Mibit, respectively¹ Megabyte (1,000,000 bytes) or mebibyte (220 = 1,048,576 bytes); the preferred symbols are MB and MiB, respectively¹ MB... Extended memory refers to memory above the first megabyte of address space in an IBM PC with an 80286 or later processor. ... Protected mode is an operational mode of x86-compatible CPUs of the 80286 series or later. ... The Intel 80286 is an x86-family 16-bit microprocessor that was introduced by Intel on February 1, 1982. ...


Graphics cards suffered from their own incompatibilities. Once graphics cards advanced to SVGA level, the standard for accessing them was no longer clear. At the time, PC programming involved using a memory model that had 64 KB memory segments. The most common VGA graphics mode's screen memory fit into a single memory segment. 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 to not number the modes consistently. An attempt at creating a standard called VBE was made, but not all manufacturers adhered to it. A GeForce 4 4200-based graphics card A graphics card or video card is a component of a computer which is designed to convert a logical representation of an image stored in memory to a signal that can be used as input for a display medium, most often a monitor... Super Video Graphics Array, almost always abbreviated to Super VGA or just SVGA is a broad term that covers a wide range of computer display standards. ... This article needs cleanup. ... On the Intel x86 architecture, a memory segment is the portion of memory which may be addressed by a single index register without changing a 16-bit segment selector. ... Video Graphics Array (VGA) is a computer display standard first marketed in 1987 by IBM. VGA belongs to a family of earlier IBM video standards and largely remains backward compatible with them. ... 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 at high resolutions and bit depths. ...


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. This time, DOS compatibility was much easier because of virtual 8086 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. Protected mode is an operational mode of x86-compatible CPUs of the 80286 series or later. ... In the 80386 and later, Virtual 8086 mode, also called virtual real mode (or VM86), allows the execution of real mode applications that violate the rules under the control of a protected mode operating system. ... DPMI is the method which Microsoft prescribes for a DOS program to run in protected mode and to access extended memory under a multitasking operating system like Microsoft Windows. ... DPMI is the method which Microsoft prescribes for a DOS program to run in protected mode and to access extended memory under a multitasking operating system like Microsoft Windows. ...


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. 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 set. The Multimedia PC, or MPC, was a recommended configuration for a PC with a CD-ROM drive. ... Year 1990 (MCMXC) was a common year starting on Monday (link displays the 1990 Gregorian calendar). ... Year 1996 (MCMXCVI) was a leap year starting on Monday (link will display full 1996 Gregorian calendar). ...


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. 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. By the mid to late 1990s, introducing a rival operating system had become too risky a commercial venture. Experience had shown that even if an operating system was superior to Windows, it would be a failure. An operating system (OS) is the software that manages the sharing of the resources of a computer and provides programmers with an interface used to access those resources. ... In computing, a platform describes some sort of framework, either in hardware or software, which allows software to run. ... Wintel is a term used to describe desktop computers and servers of the type commonly used in homes and businesses since the late 1980s (these are PC compatible computers running a version of Microsoft Windows). ... For the band, see 1990s (band). ...


However, free operating systems were being developed by enthusiasts in their spare time — for example Linux. Despite the fact that Microsoft programmers were programming for a living and the programmers working on Linux were programming as recreation, Linux became used by a great number of people in a vast number of settings. The sheer number of contributors to the Linux project allowed development effort comparable to that of the Microsoft programmers. After a couple of years, Linux had become a very powerful operating system and, because it was free, it spread widely. This article is about operating systems that use the Linux kernel. ...


Linux had become a serious alternative operating system of technically adept users by the late 1990s. It was seen as an example of what could be achieved by the open source movement. While initially lacking in software and being incompatible with Windows, Linux (like Windows NT) was shown to be more stable than Windows 9x-based operating systems in many instances. Linux has so far failed to gain marketshare outside of technically adept users, mainly due to its lack of software and hardware compatibility, and (contested) reputation of being complex and not user-friendly. Open source refers to projects that are open to the public and which draw on other projects that are freely available to the general public. ...


On the hardware front, Intel initially licensed their technology so that other manufacturers could make x86 CPUs. 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. 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 represent an evolution of the earlier Pentium III. Intel Pentium 4 (Northwood version), one example out of a huge number of x86 implementations from Intel, AMD, and others. ... “CPU” redirects here. ... Advanced Micro Devices, Inc. ... Cyrix was a CPU manufacturer that began in 1988 in Richardson, TX as a specialist supplier of high-performance math co-processors for 286 and 386 systems. ...


DirectX, while solving many of the problems in programming the PCs, was only compatible with Windows. OpenGL, which was available for several platforms, was ported to Windows, and offered a means of rapidly developing cross-platform 3D applications. Microsoft DirectX is a collection of application programming interfaces for handling tasks related to multimedia, especially game programming and video, on Microsoft platforms. ... OpenGL (Open Graphics Library) is a standard specification defining a cross-language cross-platform API for writing applications that produce 2D and 3D computer graphics. ...


The PC today

Main article: Personal computer
A modern PCs case. This is more fancy than the traditional beige box cases used throughout the 90s and late 80s.
A modern PCs case. This is more fancy than the traditional beige box cases used throughout the 90s and late 80s.

The term 'IBM PC compatible' is not commonly used for current computers. The processor speed and memory are many orders of magnitude greater than they were on the original IBM PC, yet any well-behaved program for the original IBM PC that does not call the hardware directly can still run on a modern PC. Some say that the desire for backward compatibility might have hindered the development of the PC, but many believe the ability to run legacy software is what helped keep the PC alive. Download high resolution version (750x1315, 61 KB)The tower of an Evesham (UK) 3 GHz computer. ... Download high resolution version (750x1315, 61 KB)The tower of an Evesham (UK) 3 GHz computer. ... A tower case featuring a modern design. ... This article refers to beige boxes in personal computing. ... 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. ... IBM PC (IBM 5150) with keyboard and green screen monochrome monitor (IBM 5151), running MS-DOS 5. ... This article or section does not cite its references or sources. ... It has been suggested that Legacy code be merged into this article or section. ...


The modular design makes it possible to choose every component of a PC from a variety of different manufacturers and to buy only what is needed for the tasks the computer is intended to carry out. Upgrades are easy. It is also possible to choose the operating system to run on the PC, and what software to run.


Software and compatibility amongst different PCs and hardware compatibility is no longer a major issue. There are other platforms in existence today (mostly the Apple Macintosh, which is now known as Mac), but they are a minority.


Thanks to intuitive user interfaces and the information-gathering and communications capabilities of the Internet, the computer has finally escaped from the domain of computer professionals and computer hobbyists, and has become mainstream.


The design of computer cases has become more elaborate and users can modify the cases themselves (this is known as case modding), but even so, the plain beige box case design that has been around since the '80s is still common. A tower case featuring a modern design. ... Modded PC case with light & switch, perspex window and fan hole Case modification (commonly referred to as Case modding) is the modification of a computer chassis (often just referred to as the case), or a video game console chassis. ... This article refers to beige boxes in personal computing. ...


There is a thriving demo scene, and a huge community of people willing to write free software. The demoscene is a computer sub-culture that came to prominence during the rise of the 16 bit micros (the Atari ST and the Amiga), but demos first appeared during the 8-bit era on computers such as C64 and ZX Spectrum. ... Clockwise from top: The logo of the GNU Project, the Linux kernel mascot Tux, and the BSD Daemon Free software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions only...


Hardware configurations

The Compaq Portable was one of the first portable PC compatibles that was released.
The Compaq Portable was one of the first portable PC compatibles that was released.

A PC can come in one of the following configurations: Image File history File links Size of this preview: 678 × 599 pixelsFull resolution (1086 × 960 pixel, file size: 204 KB, MIME type: image/jpeg) Compaq Portable el primer Compatible PC portable. ... Image File history File links Size of this preview: 678 × 599 pixelsFull resolution (1086 × 960 pixel, file size: 204 KB, MIME type: image/jpeg) Compaq Portable el primer Compatible PC portable. ... The Compaq Portable was the first midget in the Compaq portable series to be brought out by Compaq Computer Corporation. ... Portable communications devices refer to hand-held or wearable devices. ...


Desktop computer

A computer that sits on the top of a desk (or often under the desk, with its peripherals on top of the desk). Portability is not part of the design, so the desktop computers tend to be too heavy and too large to carry. This has the advantage that the components do not need to be miniaturised, and are therefore cheaper. It has been suggested that this article or section be merged into Computer hardware. ... Portable communications devices refer to hand-held or wearable devices. ...


Portable computer

Not long after the first IBM-PC came out, Compaq produced the Compaq Portable — one of the first portable PC compatible computers. Weighing 28 pounds, it was more of a "luggable" than a "portable". The Compaq Portable was the first midget in the Compaq portable series to be brought out by Compaq Computer Corporation. ... Portable communications devices refer to hand-held or wearable devices. ...


The portable computer evolved into the laptop. Unlike laptops, portable computers usually do not run on batteries. A Portable computer is a computer that is designed to be moved from one place to another (in other words, it is a computer that is portable). ... For the band, see Laptop (band). ... Symbols representing a single Cell (top) and Battery (bottom), used in circuit diagrams. ...


Laptop

A PC compatible laptop.

A laptop (also known as a notebook) is a PC that has been miniaturized so that it is easy to carry and can fit into a small space. It uses a flat-screen LCD which is folded onto the keyboard to create a slab-shaped object. Carrying a laptop around is easy, but this increased portability comes at a cost. To reduce size and mass, a special design is used with smaller components. These components are more expensive than regular components. The design is more integrated, meaning that it is less expandable, although the RAM and the hard drive can be upgraded (though to a lesser degree than they can be on most desktops). Laptops are also battery-powered, so as well as being smaller, the components need to have a low power usage. Image File history File linksMetadata Laptop_by_Brainiac. ... Image File history File linksMetadata Laptop_by_Brainiac. ... For the band, see Laptop (band). ... For the band, see Laptop (band). ... LCD redirects here. ... A 104-key PC US English QWERTY keyboard layout The Dvorak Simplified Keyboard layout A standard Hebrew keyboard showing both Hebrew and QWERTY. A computer keyboard is a peripheral partially modelled after the typewriter keyboard. ... For the band, see Laptop (band). ... Look up RAM, Ram, ram in Wiktionary, the free dictionary. ... Typical hard drives of the mid-1990s. ...


Palmtops and Sub-notebooks

In 1996, Toshiba produced the Libretto range of sub-notebooks (mini-notebooks). The first model (the Libretto 20) had a volume of 821.1 cm³ and weighed just 840 grams. They were fully PC compatible (unlike PDAs). There were several models produced in the Libretto range. In 2005, Toshiba announced a new model, the Libretto U100. Toshiba Corporations headquarters (Center) in Hamamatsucho, Tokyo Toshiba Corporation sales by division for year ending March 31, 2005 Toshiba Corporation ) (TYO: 6502 ) is a Japanese multinational conglomerate manufacturing company, headquartered in Tokyo, Japan. ... The Libretto 70ct with a Japanese keyboard The Libretto is a line of subnotebook computers designed and produced by Toshiba. ... To help compare different orders of magnitude, this page lists volumes between at 10-4 m3 and 10-3 m3 (100 cubic centimetres (sometimes called 100 millilitres) and 1 litre). ... Look up Personal digital assistant in Wiktionary, the free dictionary. ... The Libretto 70ct with a Japanese keyboard The Libretto is a line of subnotebook computers designed and produced by Toshiba. ...


Pocket computers

The OQO model 2 was released in 2007, and is the first PC compatible computer to fit in your pocket, this may end up supplanting traditional non-x86 PDAs such as Palm-brand ones and may eliminate the need for slow emulators for PDAs such as the Palm OS port of DOSBox and other slow virtualization suites. Previously, the common dependence on bulky connection ports and mechanical drives has limited the smallest possible size for PC-compatible computers prior to the introduction of USB. OQO is the manufacturer of a subnotebook computer named the ultra Personal Computer (UPC). ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... Palm, Inc. ... Palm OS is an embedded operating system initially developed by U.S. Robotics owned Palm Computing, Inc. ... DOS Version of Z running in DOSBox in Debian. ... Note: USB may also mean upper sideband in radio. ...


Operating systems

Over the years, there have been many operating systems for the PC: An operating system (OS) is the software that manages the sharing of the resources of a computer and provides programmers with an interface used to access those resources. ...

There were also many other OSes that however weren't well known. CP/M-86 was a version of the CP/M operating system that Digital Research made for the Intel 8086 and Intel 8088. ... Digital Research, Inc. ... This article is about the family of closely related operating systems for the IBM PC compatible platform. ... IBM PC-DOS was one of the three major operating systems that dominated the personal computer market from about 1985 to 1995. ... For other uses, see IBM (disambiguation) and Big Blue. ... Microsofts disk operating system, MS-DOS, was Microsofts implementation of DOS, which was the first popular operating system for the IBM PC, and until recently, was widely used on the PC compatible platform. ... Microsoft Corporation, (NASDAQ: MSFT, HKSE: 4338) is a multinational computer technology corporation with global annual revenue of US$44. ... This article is about the operating system. ... Device Logics DeviceLogics is a startup firm in Lindon, Utah, in 2002. ... OpenDOS is a freeware DOS-like and MS-DOS-compatible operating system. ... Enhanced Dr-DOS is a patch kit to update release 7. ... FreeDOS (formerly Free-DOS and PD-DOS) is an operating system for IBM PC compatible computers. ... A rewrite in computer programming is the act or result of re-implementing a large portion of existing functionality without re-use of its source code. ... FreeDOS 32 (or FD32 for short) is a 32-bit operating system under development for the IA-32 (also known as i386) platform, distributed under the terms of the GNU General Public License. ... “Windows” redirects here. ... This article does not cite any references or sources. ... Windows 95 is a consumer-oriented graphical user interface-based operating system. ... Windows NT (New Technology) is a family of operating systems produced by Microsoft, the first version of which was released in July 1993. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... For other uses, see IBM (disambiguation) and Big Blue. ... BeOS is an operating system for personal computers which began development by Be Inc. ... ReactOS is a project to develop an operating system that is binary-compatible with application software and device drivers for Microsoft Windows NT version 5. ... Filiation of Unix and Unix-like systems Unix (officially trademarked as UNIX®, sometimes also written as or ® with small caps) is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs including Ken Thompson, Dennis Ritchie and Douglas McIlroy. ... The Coherent operating system was introduced in 1983 by the now-defunct Mark Williams Company as one of the first Unix-like systems for IBM PC-compatible computers. ... Xenix was a version of the Unix operating system, licensed by Microsoft from AT&T in the late 1970s. ... Tarantella, Inc. ... This article is about operating systems that use the Linux kernel. ... Debian is a free operating system. ... Fedora (previously called Fedora Core) is a yum and RPM-based GNU/Linux distribution, developed by the community-supported Fedora Project and sponsored by Red Hat. ... Red Hat Enterprise Linux (often abbreviated to RHEL) is a Linux distribution produced by Red Hat and targeted toward the commercial market, including mainframes. ... Red Hat, Inc. ... Ubuntu (official IPA pronunciation (oo-BOON-too[5])) is a predominantly desktop-oriented Linux distribution, based on Debian GNU/Linux but with a stronger focus on usability, regular releases, and ease of installation. ... The Gentoo Linux operating system (pronounced ) is a Linux distribution named after the Gentoo penguin. ... Mandriva (merger of Mandrakesoft, Lycoris, and Conectiva) is a French software company, and creator of Mandriva Linux. ... Slackware was one of the earliest Linux distributions, and is the oldest, and most UNIX-like, distribution still being maintained[1]. It was created by Patrick Volkerding of Slackware Linux, Inc. ... SUSE (properly pronounced , but often pronounced /suzi/) is a major retail Linux distribution, produced in Germany. ... This page provides general information about notable Linux distributions in the form of a categorized list. ... BSD redirects here; for other uses see BSD (disambiguation). ... OpenBSD is a Unix-like computer operating system descended from Berkeley Software Distribution (BSD), a Unix derivative developed at the University of California, Berkeley. ... NetBSD is a freely redistributable, open source version of the Unix-like BSD computer operating system. ... FreeBSD is a Unix-like free operating system descended from AT&T UNIX via the Berkeley Software Distribution (BSD) branch through the 386BSD and 4. ... The DragonFly BSD Logo In computing, the DragonFly BSD operating system is a fork of FreeBSD. Matt Dillon, a long-time FreeBSD and Amiga developer, started work on DragonFly BSD in June 2003 and announced it on the FreeBSD mailing lists on 16 July 2003. ... Solaris is a computer operating system developed by Sun Microsystems. ...


See also

Computer hardware is the physical part of a computer, including the digital circuitry, as distinguished from the computer software that executes within the hardware. ... Software redirects here. ... IBM PC (IBM 5150) with keyboard and green screen monochrome monitor (IBM 5151), running MS-DOS 5. ... A Homebuilt Computer system is one assembled from available components, rather than purchased as a complete system from a computer system supplier. ... The history of computing hardware starting in the 1960s begins with the development of the integrated circuit (IC), which formed the basis of the first computer kits and home computers in the 1970s, notable examples being the MITS Altair, Apple II and Commodore PET; and which eventually powered personal and... The PC speaker is the most primitive sound system used in IBM compatible PCs, and in fact used to be the only one in use in PC games before more technologically advanced sound cards such as AdLib or the Sound Blaster were introduced as ISA plug-in cards in the... Baby AT motherboard. ... Intel Pentium 4 (Northwood version), one example out of a huge number of x86 implementations from Intel, AMD, and others. ...

Notes

  1. ^ Lotus 1-2-3 and Context MBA belonged to a now-mostly-forgotten genre known as "integrated software", today exemplified by Microsoft Works and AppleWorks. Before GUIs, user interfaces were mediated mostly by command keys, and every program had a unique user interface, making it difficult for a user to master more than one or two programs. And the lack of hard disk drives made programs slow to launch, making it inconvenient to use more than one program to accomplish a task. In response to this, monolithic multifunction "integrated" packages arose. Lotus 1-2-3 was built as a three-function "integrated" program: spreadsheet, database, and chart-making. Context MBA included these functions plus a word processor and terminal emulator, the same five functions to be included years later in Lotus Symphony

  Results from FactBites:
 
IBM PC compatible - Wikipedia, the free encyclopedia (4588 words)
The term "IBM PC Compatible" is on the wane.
Although the IBM PC was designed for expandability, the designers could not anticipate the hardware developments of the '80s.
The original IBM PC is long forgotten and the term PC compatible is not used.
IBM PC - Wikipedia, the free encyclopedia (2050 words)
The original 1981 IBM PC's keyboard was severely criticised by typists for its non-standard placement of the return and left shift keys.
If a hard disk was added that was not compatible with the existing disk controller, a new controller board had to be plugged in; some disks were integrated with their controller in a single expansion board.
In 1988 IBM introduced a drive for 2.88 megabyte "DSED" diskettes in its top-of-the-line models; it was an instant failure and is all but forgotten today (but survives as a possible "size" choice in disk-formatting utilities).
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