The role of the BIOS has changed over time.

The term BIOS ( Basic Input / Output System ) was invented by Gary Kildall and first appeared in the CP / M operating system in 1975, describing the machine-specific part of CP / M loaded during boot time that interfaces directly with the hardware ( a CP / M machine usually has only a simple boot loader in its ROM ).

On recent motherboards, the BIOS may also patch the central processor microcode if the BIOS detects that the installed CPU is one in for which errata has been published.

The BIOS on the IBM-PC class machines was an extension of this idea and has accreted more features and functions in the 20 years since the first IBM-PC was introduced in 1981.

This is because the operating system ( through the BIOS ) has a certain set of protocols or rules for communication with the drive that cannot be violated ( such as when the hard drive detects a bad sector ).

It is sometimes possible to change the BIOS ( e. g. to enable factory-locked settings for higher performance ), although this is typically only done by video card overclockers and has the potential to irreversibly damage the card.

AMD Athlon XP overclocking BIOS setup on ABIT NF7-S. Front side bus frequency ( external clock ) has increased from 133 Hertz | MHz to 148 MHz, and the clock multiplier factor has changed from 13. 5 to 16. 5

Much emphasis has been put on machines with motherboards based on the Intel 430TX chipset, but by far the most important variable in CIH's success in writing to a machine's BIOS is the type of Flash ROM chip in the machine.

* The Xbox does not have an operating system per se, instead it only has a basic BIOS.

Mike Riley has written an editor, assembler, BASIC and FORTH interpreters, a BIOS, and the Elf / OS disk operating system that will run on expanded ELF systems, including the COSMAC Elf 2000.

In comparison to conventional methods of remote administration ( for example in-band Virtual Network Computing or Terminal Services ), a KVM switch has the advantage that it doesn't depend on a software component running on the remote computer, thus allowing remote interaction with base level BIOS settings and monitoring of the entire booting process before, during, and after the operating system loads.

Dr. Wong has released a book based on this popular online guide called Breaking Through The BIOS Barrier: The Definitive BIOS Optimization Guide for PCs which was published by Prentice Hall in late 2004.

The WD740ADFD has also caused problems in some motherboards and their manufacturers had to release BIOS updates.

Another porting aid is the commercial " RD1 BIOS Savior " product from IOSS, which is a combination of two boot memory devices that plugs into the boot memory socket and has a manual switch to select between the two devices.

Once it has done this, any subsequent calls to INT 13H will be " caught " by the SCSI option ROM ( or " SCSI BIOS "), allowing it to insert details about any disks that may exist on the SCSI bus.

In this particular case, the BIOS itself may call INT 13 to provide a list of possible boot devices to the user, and because the SCSI BIOS has hooked the interrupt the user will be able to choose not only which standard system devices to boot from, but also which SCSI disks as well.

IPMI is a message-based, hardware-level interface specification: an IPMI sub-system operates independently of the operating system ( OS ) to allow administrators to manage a system remotely in the absence of an operating system or of the system management software, and thus can be used before an OS has booted ( allowing e. g. BIOS settings to be remotely monitored or changed ), when the system is powered down, or after OS or system failure, which is the key characteristic of IPMI compared with in-band system management by e. g. remote login such as SSH.

Instead of adding code to the kernel, as in the old scheme, or using kernel facilities as in the kernel-based scheme, it traps all calls to a file and identifies if it should be redirected to the kernel's equivalent function or if it has to be handled by the specific filesystem driver, and the filesystem driver " directly " access the disk contents using low-level BIOS functions.

The term remains in wide use but it has grown into a misnomer: nonvolatile storage in contemporary computers is often in EEPROM or flash memory ( like the BIOS code itself ); the remaining usage for the battery is then to keep the real-time clock going.

If the x86 processor supports this feature in hardware, and if the system's BIOS provides support for this feature and it has been enabled, either by the manufacturer or the user, then the NX features are turned on in Windows, on a limited " OptIn " basis.

In the BIOS UI, a user can:

* set various password prompts, such as a password for securing access to the BIOS user interface functions itself and preventing malicious users from booting the system from unauthorized peripheral devices.

However, the distinction between BIOS and EFI is rarely made in terminology by the average computer user, making BIOS a catch-all term for both systems.

This usually required a user to download and install a modified Doctor V64 BIOS.

The BIOS may be " manually " updated by a user, using a small utility program.

As an example, in the area of personal computers, some BIOS writers include the ability to disable spread-spectrum clock generation as a user setting, thereby defeating the object of the EMI regulations.

Many motherboards allow the user to manually set the clock multiplier and FSB settings by changing jumpers or BIOS settings.

Motherboards purchased separately to build a custom machine are more likely to allow the user to edit the multiplier and FSB settings in the PC's BIOS.

The beep is also sometimes used to notify the user when the BIOS is not working or there is some other error during the start up process, often during the power-on self-test ( POST ).

In this case a multi-booting boot loader is not strictly necessary because the user can choose to enter BIOS configuration immediately after power-up and make the desired drive first in the boot-order list.

However, it is more convenient to have a multi-booting boot loader on one of the drives, set BIOS once to always start booting from ( i. e., load the boot loader from ) that drive, and then allow the user to choose an operating system from that boot loader's menu.

EvoX, not to be confused with the EvolutionX dashboard, is a replacement Xbox BIOS, that allows a user with a modchip or a TSOP flash, to boot unsigned code, and game backups.

When this battery failed the computer would not boot until the user edited the configurable BIOS parameters.

For this reason, ePSXe does not come bundled with any of the PlayStation BIOS images, requiring the user to provide one for the emulator.

The F-series infra-red keyboards contained a real-time clock ; during the machine's boot sequence, the BIOS would graphically prompt the user to press the ' DATE / TIME ' key.

In computing, the System Management BIOS ( SMBIOS ) specification defines data structures ( and access methods ) in a BIOS which allows a user or application to store and retrieve information specifically about the computer in question.

This provided a more standardized approach where an option ROM could be initialized at the start of the boot process, it could inform the BIOS about its functionality, and then it could be called later on in the boot process depending on the order the user had selected.

However, newer BIOS setups do not include an RTC alarm option, although it can still be set from within user applications.

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.

** using some higher-level interface ( e. g. Video BIOS )

Wake-on-LAN support is implemented on the motherboard ( BIOS ) of a computer and the network interface ( firmware ), and is consequently not dependent on the operating system ( and NIC drivers ) running on the hardware.

While the BIOS video interface routines were adequate for rudimentary output, they were inefficient ; they did not have " string " output ( only output by individual character ) and they inserted delay periods to compensate for CGA hardware " snow " ( a display artifact of CGA cards produced when writing directly to screen memory )-- an especially bad artifact since they were called by IRQs, thus making multitasking very difficult.

To make a BIOS call for every point drawn or modified also increased overhead considerably, making the BIOS interface notoriously slow.

VESA BIOS Extensions ( VBE ) is 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.

Floppy disk drives were available for MSX however, in the form of a cartridge containing the disk interface electronics and a BIOS extension ROM ( the floppy disk drive interface ), connected to an external case with the drive.

* System Management BIOS ( SMBIOS ) – defines how the BIOS interface of x86 architecture systems is represented in CIM ( and DMI ).

Originally requiring the use of a boot floppy disk to establish the initial network connection, manufacturers of network cards later embedded the protocol in the BIOS of the interface cards as well as system boards with on-board network adapters, thus allowing direct network booting.

The PCjr, IBM model number 4860, retained the IBM PC's 8088 CPU and BIOS interface for compatibility, but various design and implementation decisions led the PCjr to be a commercial failure.

Function Keys are also heavily used in the BIOS interface.

Even further, " AT-class " became a term describing any machine which supported the BIOS functions, 16-bit expansion slots, keyboard interface, and other defining technical features of the IBM PC AT ; in the case of the expansion slots, the term is largely synonymous with " ISA " ( when the latter is not applied as a retronym to XT-class machines, as in the phrase " 8-bit ISA slot ".

To further overcome this limit, INT 13H Extensions were introduced with BIOS Enhanced Disk Drive Services specification, which removed practical limits on disk size for operating systems which are aware of this new interface, such as DOS 7. 0 component in Windows 95.

* Protected Area Run Time Interface Extension Services ( PARTIES ), a BIOS interface to access reserved areas on harddisks

If at least the CPU, BIOS, and the I / O interface the POST card relies on are working, the system sends two-hexadecimal-digit codes to a specified I / O port ( usually 80 hex ) during startup, some indicating a stage in the startup procedure, others identifying errors.

UEFI is meant as a replacement for the BIOS firmware interface, present in all IBM PC-compatible personal computers.

The Smart Battery System define the SMBus connection, the data that can be sent over the connection ( Smart Battery Data or SBD ), the Smart Battery Charger, and a computer BIOS interface for control.

At approximately the same time Microsoft started to require that OEMs and BIOS vendors support the interface / data-set in order to have Microsoft certification.