IBM PC compatible

As an IBM PC compatible computer or IBM -compatible PC you designated historically personal computer or microcomputer, which were modeled on the technical design of the IBM PC in 1981 and its successor models such as the IBM PC / AT. Less often the replicas are also known as IBM clones ( or clones ), as they were technically almost identical copies actually, especially in the early years. Later the term was IBM - compatible uses rare and much more generally for systems that simulate a microprocessor type x86 and start an appropriate BIOS. The latter is replaced by the more modern EFI.

IBM PC compatible computers are also referred to as PC as a platform in distinction from Apple Macintosh models, the Atari ST series and others. Since the term personal computer was used but early for other than x86 -based platforms, this designation was not always clear. Due to the massive spread of compatible x86 personal computers that the importance of IBM back in the 1980s, fell sharply as the initial leader. In 1987, the newly developed IBM PS/2-Reihe on the market that completely broke and proprietary technologies such as the Micro Channel bus system introduced with the previous PC concept, which were no longer freely available consciously for other manufacturers.

Thus, the IBM PC was even more paradoxically, not IBM PC compatible, making IBM underwent the self-imposed industry standard. This, however, was a commercial failure, as large PC makers such as Compaq did not with these swivel. They sat instead successfully own technical standards such as the EISA bus as a rival to the Micro Channel concept. Through the sale of its PC business to Lenovo in 2005, IBM has finally retired completely from the PC area.

For these reasons, the term IBM - PC compatible outdated and technically since the PS/2-Linie no longer correct, which is why it is now being used any more. Current terms for x86-based computers are mainly the terms PC, Windows PC or Windows computer, according to the dominant operating system, or more rarely Wintel computer as portmanteau of Windows and Intel, the leading x86 processor manufacturer.

History

Since the IBM PC - in contrast to his former competing products - was built exclusively with commercially available standard components (Commercial off-the -shelf ), this led to numerous imitations. The IBM PC became an unofficial industry standard because it could be rebuilt without license from IBM. At IBM, even those imitations were somewhat looking down called IBM PC convertible.

With the introduction of new processors from I286 and all subsequent models with 32- bit word width of the chip maker Intel integrated one (virtual) 8086 on the chip, so continue x86 -compatible computers could be built. To keep the power consumption of today's chips as low as possible, the 8086 functionality is now integrated in the processor emulated by firmware. Depending on the manufacturer and carry the CPU used for emulation microcode names such as ROP, micro-op or μOp.

Future

If the EFI does not provide BIOS compatibility is a computer without the IBM -compatible BIOS no more than IBM - compatible in to understand " strict sense ". Only an IBM - compatible BIOS allows booting an IBM - PC compatible DOS operating system, and thus the possibility in principle of the respective computer to use just like an IBM PC of 1981. The DOS operating systems require the main board specific BIOS as a hardware abstraction layer for accessing the BIOS known resources of the motherboard and standardized expansion cards. Thus DOS operating systems can not boot and programs for the IBM PC will not run natively on the respective system without an IBM - compatible BIOS. A computer without IBM - compatible BIOS is thus basically not IBM compatible.

In modern operating systems with multitasking capability hardware access must be coordinated. These are made here, bypassing the BIOS directly from the device driver; the BIOS is only needed at boot to start the operating system.

For this reason, the BIOS has been freed from perceived as superfluous ballast over the years. It has already been a number of PC manufacturers on the original IBM PC existing ROM Basic waived in the 1980s that the IBM PC was launched, when he found no disk with the operating system. An implementation would have required extra effort and may require permission of IBM. The hardware abstraction interface for the datasettes port disappeared relatively quickly due to lack of use of the BIOS code of the PC clone manufacturers. In today's PC motherboards with BIOS the floppy interface is also saved to the BIOS page or severely limited, often only one drive configured. Also supporting older floppy drive types is questionable by current BIOS versions.

Strictly speaking, these systems are therefore to be regarded as only partially IBM - PC compatible, since the original IBM PC providing for example the connection of Datasette and several 5.25 "floppy drives, both on the hardware and on the software side, what is no longer just offer modern computer because hardware and operating systems have evolved. on these developments, the PC architecture was continuously adjusted by adding and omitting elements over the years. Thus it can be stated that the degree of compatibility with the IBM - PC has dropped already to some extent in the 1980s, but even after detachment from DOS through Windows 95 with the consequent dwindling importance of the BIOS and on.

The core elements of an IBM PC -compatible computers remained over the years a x86-compatible central processing unit, which starts a BIOS, which it essentially remains the functionality of the BIOS of the original IBM PC, adapted to the requirements of modern hardware and software, maps. This also makes it on modern systems generally still possible to use DOS operating systems and hence numerous programs for the original IBM PC, so the compatibility of modern systems still added to their " ancestor " and is to be regarded as high.

In the medium term is a further drop this compatibility level to be expected since many classic BIOS functions are less and less in demand. With the BIOS successor EFI a final end to the era is in some way " IBM PC - compatible computer " in sight, even if for a start may still be realized with BIOS-compatible functions for older operating systems EFI. However, it is anticipated that these residual functions are then less and less in demand by software, and thus gradually disappear from the firmware. By EFI and the announcement of Microsoft's Windows 8 also be able to use EFI instead of a BIOS for booting the operating system is finally ushered in the slow end of the BIOS and thus the IBM - PC compatible computer.

As modern operating systems to abstract more and more hardware internals in different ' layers ' and patch runtime environments, the importance of these changes, which take place at the lower levels, nowadays hardly relevant. Today, the operating systems with different firmwares or loaders, often also deal with very different hardware architectures such as ARM SoCs. The term " IBM PC compatible computer " is on a plane that is only for a few users of interest now, and thus rarely used. Today is the question of compatibility with certain operating systems, which still of interest to users - including, for example, in the case of Windows mostly compatibility with the IBM PC.

Interfaces

Thus, the available for IBM - PC compatible computer operating systems work with various hardware extensions, except the x86-compatible processor also requires uniform interfaces. The Ur PC decreed internal 8 -bit ISA slots as well as a connection for up to two floppy disk drives. Externally there were serial and parallel ports and a keyboard port, such as a digital MDA monitor port for monochrome text displays. These interfaces, however, were expanded and modernized in the course of development.

Operating Systems

For IBM PC -compatible computers almost all operating systems are available. Commonly used are:

DOS
Microsoft Windows
OS / 2
Linux and various Unix derivatives

IBM Personal Computer Clone (computing) Unified Extensible Firmware Interface Luigi Colani Commercial off-the-shelf IBM Monochrome Display Adapter IEEE 1394 BeOS IA-32 X86-64 AT (form factor) ATX BTX (form factor)

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