Basic Input
Output System
The BIOS has a
number of different roles, but its most important role is to
load the operating system. When you turn on your computer
and the microprocessor tries to execute its first
instruction, it has to get that instruction from somewhere.
It cannot get it from the operating system because the
operating system is located on a hard disk, and the
microprocessor cannot get to it without some instructions
that tell it how. The BIOS provides those instructions. Some
of the other common tasks that the BIOS performs include:
A power-on
self-test (POST) for all of the different hardware
components in the system to make sure everything is working
properly.
Activating other
BIOS chips on different cards installed in the computer -
For example, SCSI and graphics cards often have their own
BIOS chips.
Providing a set of
low-level routines that the operating system uses to
interface to different hardware devices - It is these
routines that give the BIOS its name. They manage things
like the keyboard, the screen, and the serial and parallel
ports, especially when the computer is booting.
The BIOS is special
software that interfaces the major hardware components of
your computer with the operating system. It is usually
stored on a Flash memory chip on the motherboard, but
sometimes the chip is another type of ROM.