▷ What is bios and what is it for 【the best explanation】

BIOS is an acronym for Basic Input / Output System, it is a non-volatile firmware that is used to perform hardware initialization during the startup process, and to provide runtime services for operating systems and programs.

Everything you need to know about your PC's BIOS, its features and functions

The BIOS firmware comes pre-installed on the system board of every PC, and is the first software to run when powered on. Originally owned by the IBM PC, it has been reverse engineered by companies looking to create compatible systems. The interface of that original system serves as a de facto standard.

We recommend reading our article on How to reset the BIOS of the motherboard

The BIOS on modern PCs initializes and tests the hardware components of the system, and loads a bootloader from a mass memory device, which then initializes an operating system. In the MS-DOS era, BIOS provided a hardware abstraction layer for the keyboard, display, and other input / output (I / O) devices that standardized an interface for application programs and the operating system. Newer operating systems do not use it after charging, instead accessing hardware components directly.

Most BIOS implementations are specifically designed to work with a particular motherboard model, by interacting with various devices that make up the complementary system chipset. Originally, the BIOS firmware was stored on a ROM chip on the PC motherboard. In modern computer systems, the BIOS content is stored in flash memory so that it can be rewritten without removing the chip from the motherboard. This allows the user to easily perform BIOS firmware updates, so that new features can be added or errors can be corrected, but it also creates the possibility for the PC to become infected with BIOS rootkits. Also, a failed BIOS update can crash the motherboard permanently, unless the system includes some kind of backup in this case.

The term was created by Gary Kildall, and it first appeared in the CP / M operating system in 1975, which describes the machine as a specific part of CP / M, loaded at boot time, that connects directly to hardware. The versions of MS-DOS, PC DOS or DR-DOS contain a file named "IO.SYS", "IBMBIO.COM", "IBMBIO.SYS" or "DRBIOS.SYS "; This file is known as "DOS BIOS, " and it contains the specific part of the lower-level hardware of the operating system.

BIOS is a fundamental part of your motherboard

The BIOS ROM is customized for the particular manufacturer's hardware, allowing low-level services, such as reading a keystroke or writing a data sector to a floppy disk, to be provided in a standardized way to programs, including operating systems. For example, an IBM PC may have a monochrome or color display adapter, but a single, standard system call can be invoked to display a character at a specific position on the screen, in text or graphic mode.

BIOS provides a small library of basic input / output functions for operating peripherals such as keyboard, rudimentary text, and graphic display functions, etc. When using MS-DOS, services can be accessed by an application program, or by MS-DOS by executing an INT 13h interrupt instruction to access disk functions, or by executing one of several other documented interrupt calls to access to the screen, keyboard, cassette and other device functions.

Operating systems and executive software that are designed to replace this basic firmware functionality provide replacement software interfaces for the application software. Applications can also provide these services to themselves. This started even in the 1980s with MS-DOS, when programmers observed that the use of video services for graphics display was very slow. To increase the screen output speed, many programs bypassed it and programmed the video display hardware directly. Other graphic programmers noted that there were technical capabilities of PC display adapters that were not supported, and could not be exploited without circumventing them. Since the AT-compliant BIOS ran in Intel real mode, operating systems operating in protected mode on 286 and later processors required hardware device drivers, compatible with protected-mode operation to replace BIOS services.

On PCs running modern operating systems, the BIOS is used only during startup and initial loading of the system software. Before the first graphical display of the operating system is displayed, input and output are normally handled through the BIOS. A start menu, such as the Windows text menu, which allows users to choose an operating system to start, boot in safe mode, or use the last known valid configuration, is displayed through the BIOS and receives keyboard input.

Most modern PCs can still start and run legacy operating systems like MS-DOS or DR-DOS, which rely heavily on the BIOS for their console and disk I / O, provided the system has a BIOS or a compatible firmware, which is not necessarily the case for UEFI-based PCs.

This ends our special article on what the BIOS is and what it is for, remember that you can share it on social networks so that it can help more users who need it.

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