1. Initialization (ignition) as well as testing of the hardware (in a process called the Power On Self Test, POST)
2. Load and run the operating system
3. Set some basic configuration of the computer (date, time, storage configuration, the configuration of the boot process, performance, and stability of your computer)
4. Helping operating systems and applications in the process of hardware setup using the BIOS Runtime Services.
BIOS provides low level communication interface, and can control many types of hardware (like keyboards). Because of its proximity to the hardware, the BIOS is generally made by using assembly language (assembly) that is used by the machine in question.
The term first appeared in the BIOS operating system CP / M, which is part of CP / M loaded during the booting process started dealing directly with hardware (multiple machines running CP / M has a simple boot loader in ROM). Most versions of DOS have a file called "IBMBIO.COM" (IBM PC-DOS) or "IO.SYS" (MS-DOS), which functions just as well as CP / M disk BIOS.
BIOS word can also mean "life" in Greek writings (Βίος).