Award BIOS setup utility on a standard PC

In IBM PC compatible computers, the Basic Input / Output System ( BIOS ), also known as the system BIOS or ROM BIOS (), is a de facto standard defining a firmware interface.

The BIOS software is built into the PC, and is the first code run by a PC when powered on (' boot firmware ').

When the PC starts up, the first job for the BIOS is the power-on self-test, which initializes and identifies system devices such as the CPU, RAM, video display card, keyboard and mouse, hard disk drive, optical disc drive and other hardware.

The BIOS then locates boot loader software held on a peripheral device ( designated as a ' boot device '), such as a hard disk or a CD / DVD, and loads and executes that software, giving it control of the PC.

A BIOS has a user interface ( UI ), typically a menu system accessed by pressing a certain key on the keyboard when the PC starts.

In the IBM PC and AT, certain peripheral cards, such as hard-drive controllers and video display adapters, carried their own BIOS extension Option ROM, which provided additional functionality.

For example, an IBM PC might have either a monochrome or a color display adapter ( using different display memory addresses and hardware ), but a single, standard, BIOS system call may be invoked to display a character at a specified position on the screen in text mode.

In the PC / AT introduced in 1984, IBM added external circuitry as well as specialized code in the ROM BIOS to enable special series of program instructions to cause the reset, allowing real-mode reentry ( while retaining active memory and control ).

Unlike the IBM PC, which used 8 kB of system ROM for power-on self-test ( POST ) and basic input / output system ( BIOS ), the Mac ROM was significantly larger ( 64 kB ) and held key OS code.

Wake-on-LAN usually needs to be enabled in the Power Management section of a PC motherboard's BIOS setup utility, although on some systems, such as Apple computers, it is enabled by default.

In many desktop computers, for example, the bootstrapping process begins with the CPU executing software contained in ROM ( for example, the BIOS of an IBM PC ) at a predefined address ( some CPUs, including the Intel x86 series are designed to execute this software after reset without outside help ).

) Windowed CERDIP-packaged PROMs were used for the BIOS ROM of many early IBM PC clones ( which were manufactured in limited enough quantities to make PROM an economical choice ) often with a foil-backed ( or regular paper ) adhesive label covering the window to prevent inadvertent erasure through exposure to ambient light.

They duplicated almost exactly all the significant features of the PC architecture, facilitated by various manufacturers ' ability to reverse engineer the BIOS using a " clean room design " technique.

The only proprietary component of the original PC architecture was the BIOS ( Basic Input / Output System ).

Although Compaq kept its BIOS proprietary, 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.

The most notable exceptions are probably the Dreamcast game console which includes a minimal BIOS, like the PlayStation, but can load the Windows CE operating system from the game disk allowing easily porting of games from the PC world, and the Xbox game console, which is little more than a disguised Intel-based PC running a secret, modified version of Microsoft Windows in the background.

Old PC BIOS chips were often EPROMs, and the erasing window was often covered with an adhesive label containing the BIOS publisher's name, the BIOS revision, and a copyright notice.

Due to cartridge storage limitations, the Nintendo 64 version is based on the original PC floppy version and lacks the FMV scenes and Redbook audio music introduced in the CD-ROM version, although it has new narrative introductions to the levels.

To make things worse, IBM's choice of the Intel 8088 for the CPU introduced several limitations for developing software for the PC compatible platform.

The PC CPUs of the time had limitations in memory capacity and memory access protection, making them unsuitable to run OSes of this sophistication, but this, too, began to change in the late 1980s as PCs with the 32-bit 80386 with integrated paged MMUs became widely affordable.

In spite of these limitations, in less than a year, the Sound Blaster became the top-selling expansion card for the PC.

Most PC serial ports, the traditional interface for external hardware modems, are limited to 115, 200 bits per second by UART limitations, though some ports are capable of 230, 400 bit / s.

A number of patches from various vendors were included on a single " combo-cartridge ", licensed and sold by PC Enterprises, to support add-on hardware, bypass certain limitations of design, and keep up with changing OS requirements.

In contrast to earlier, largely failed attempts to establish mini computers as a new class of mainstream personal computing devices built around comparatively expensive platforms requiring proprietary software applications or imposing severe usability limitations, the recent success of netbooks can also be attributed to the fact that PC technology has now matured enough to allow truly cost optimized implementations with enough performance to suit the needs of a majority of PC users.

Computer Gaming World similarly felt that the limitations of the PlayStation carried over in the PC port, rendering the latter's visuals " mind-numbingly boring ".

Empix is quite small ( about 10, 000 lines of code ) and supports PC XT and AT architectures, floppy disks and hard drives ( with the FAT16 limitations ), as well as EGA graphics ( 80x25 color terminal ) and the serial ports.

The flip-screen technique was particularly common in PC games originally made for the ZX Spectrum, such as Atic Atac, Jet Set Willy, and Starquake, due in part to the Spectrum's display limitations which meant that full colour scrolling was difficult to implement convincingly-Light Force being a notable exception.

These limitations were not exclusive to the Spectrum ; many early MSX, NEC PC-8801 and PC VGA games also used the flip-screen technique.

Although it forms a part of the Extensible Firmware Interface ( EFI ) standard ( Intel's proposed replacement for the PC BIOS ), it is also used on some BIOS systems because of the limitations of MBR partition tables, which uses 32 bits for storing logical block addresses and size information.

The PC / AT, introduced in 1984, had three 8-bit slots and five 16-bit slots, all running at the system clock speed of 6 MHz in the earlier models and 8 MHz in the last version of the computer.

IBM designed the 8-bit version as a buffered interface to the external bus of the Intel 8088 ( 16 / 8 bit ) CPU used in the original IBM PC and PC / XT, and the 16-bit version as an upgrade for the external bus of the Intel 80286 CPU used in the IBM AT.

The 8-bit bus ran at 4. 77 MHz ( the clock speed of the IBM PC and IBM PC / XT's 8088 CPU ), while the 16-bit bus operated at 6 or 8 MHz ( because the 80286 CPUs in IBM PC / AT computers ran at 6 MHz in early models and 8 MHz in later models.

) IBM RT / PC also used the 16-bit bus.

** Relative 16-bit signed offset, e. g. 16 ( PC ).

* 1987 – In Japan, NEC releases the first 16-bit ( fourth generation ) video game console, the PC Engine, which was later sold in other markets under the name TurboGrafx-16.

This was several years prior to successful GUIs on the 16-bit IBM PC class machines, and many years prior to properly working multi-tasking, multi-user, access-controlled operating systems on IBM PC type machines or on any of Apple's machines.

These are often physically small compared to a standard PC, although still quite large compared to most simple ( 8 / 16-bit ) embedded systems.

The Atari demo scene started to peter out around 1993 as the popularity of the 16-bit micros was overtaken by the relentless advance of the x86 based PC.

After 1987, IBM PC compatibles dominated both the home and business markets of commodity computers, with other notable alternative architectures being used in niche markets, like the Macintosh computers offered by Apple Inc. and used mainly for desktop publishing at the time, the aging 8-bit Commodore 64 which was selling for $ 150 by this time and became the world's best-selling computer, the 16-bit Commodore Amiga line used for television and video production and the 16-bit Atari ST used by the music industry.

Type-III PC Card devices are 16-bit or 32-bit.

Most new slots accept both CardBus and the original 16-bit PC Card devices.

* Understanding PC Card, PCMCIA, Cardbus, 16-bit, 32-bit.

This connector allows use of a number of compatible peripherals available for the laptop market, though only 16-bit ( Type II ) PCMCIA cards are hardware compatible, newer 32-bit CardBus or PC Card peripherals are incompatible.

VGA was the last graphical standard introduced by IBM that the majority of PC clone manufacturers conformed to, making it today () the lowest common denominator that almost all post-1990 PC graphics hardware can be expected to implement down to the lowest level of hardware registers, obviating the need for any device-specific firmware or driver software ( while all VGA compatible hardware has on-board firmware as well, the only standardized API of that firmware was created for 16-bit real mode and can't easily be used by newer 32-or 64-bit operating systems ).

It converts any audio signals on a PC or game console into a 5. 1-channel 16-bit / 48 kHz Dolby Digital format at 640 kbit / s and transports it via a single S / PDIF cable.

The PC clone market did not want to pay royalties to IBM in order to use this new technology, and for desktop machines vendors of PC-compatibles stayed largely with the 16-bit AT bus, ( embraced and renamed as ISA to avoid IBM's " AT " trademark ) and manual configuration, although the VESA Local Bus was briefly popular for Intel ' 486 machines.

The popularity of IBM's first personal computers made the ISA bus, first used on the IBM PC in 1981 and later extended to 16-bit in 1984 with the IBM PC / AT, the undisputed standard expansion bus for personal computers shortly after.