BIOS
This page describes the BIOS, one of two methods for finding and loading a boot loader. The
other, method is the UEFI which is the newer method of
accomplishing the same thing.
BIOS stands for Basic Input Output System. It is the only piece of
software that is stored in non-volitile memory. That means that the
contents of memory are not lost even when the power has been turned off and then on. Thus it is available for execution as soon as the CPU has finished its power-on reset.
The BIOS is divided into four components:
- Drivers: These are special-purpose pieces of software, each
designed to control a specific I/O device. There is a
keyboard driver, display driver, disk driver, etc.
- Power On Self Test (POST) This is the component
that initially gains control during a boot sequence. Its purpose
is to test and initialize various hardware components.
- Setup: System setup is designed to allow the user to configure
very low-level hardware information. This is the only part of the
BIOS that interacts with the user. To enter Setup, the user
presses some specified key during the POST. Which key depends on
who wrote the BIOS; common keys are DEL or F2.
- Boot. If the user didn't press the
special key to invoke Setup, then when the POST is finished it will
transfer control the the Boot routine.
Next: Power On Self Test (POST)
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