The Basic Input/Output System (BIOS), also known as the System BIOS, is a de facto standard defining a firmware interface.
The BIOS is boot firmware, designed to be the first code run by a PC when powered on. The initial function of the BIOS is to identify, test, and initialize system devices such as the video display card, hard disk, and floppy disk and other hardware. This is to prepare the machine into a known state, so that software stored on compatible media can be loaded, executed, and given control of the PC. This process is known as booting, or booting up, which is short for bootstrapping.
BIOS programs are stored on a chip and are built to work with various devices that make up the complementary chipset of the system. They provide a small library of basic input/output functions that can be called to operate and control the peripherals such as the keyboard, text display functions and so forth. In the IBM PC and AT, certain peripheral cards such as hard-drive controllers and video display adapters carried their own BIOS extension ROM, which provided additional functionality. Operating systems and executive software, designed to supersede this basic firmware functionality, will provide replacement software interfaces to applications.
- AMIBIOS8_Checkpoint_and_Beep_Code_List by American MegaTrends
- How BIOS Works by Sixto Ortiz, Jr.