The BIOS software is built into the PC, and is the first code run by a PC when powered on ('boot firmware'). The primary function of the BIOS is to load and start an operating system.
The Basic Input/Output System (BIOS), also known as the system BIOS or ROM BIOS ( /ˈbaɪ.oʊs/), 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.[2] This process is known as booting, or booting up, which is short for bootstrapping. BIOS software is stored on a non-volatile ROM chip on the motherboard. It is specifically designed to work with each particular model of computer, interfacing with various devices that make up the complementary chipset of the system. In modern computer systems, the BIOS chip's contents can be rewritten without removing it from the motherboard, allowing BIOS software to be upgraded in place.
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 BIOS UI, a user can:
- configure hardware
- set the system clock
- enable or disable system components
- select which devices are eligible to be a potential boot device
- 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.
