Chapter 4: System Bios; What Is The Bios; The Power-On Sequence - Viglen Vig535b Manual

Chapter 4: System BIOS

What is the BIOS?

The BIOS (Basic Input Output System) is an important piece of software which is
stored in a ROM (Read Only Memory) chip inside the computer. It consists of the
basic instructions for controlling the disk drives, hard disk, keyboard and
serial/parallel ports. The BIOS also keeps a list of the specifications of the computer
in battery-backed RAM (also known as the CMOS RAM) and provides a special
Setup program to change this information.
The BIOS in your Viglen computer is guaranteed to be fully compatible with the IBM
BIOS. It has been written by American MegaTrends Inc. (AMI), an industrial leader in
the field of BIOS software.

The Power-On sequence

When the computer is first switched on, certain instructions in the BIOS are executed
to test various parts of the machine. This is known as the POST (Power-On Self
Test) routine. When you switch the computer on (or when you press the Reset
button or press <Ctrl> + <Alt>+ <Delete> keys, which has the same effect), you can
see on the monitor that it counts through the memory, testing it. The floppy disk
drives are then accessed and tested, and the various interfaces are checked. If there
are any errors, a message is displayed on the screen.
Having passed all the tests, and if you have activated the password facility, the BIOS
then asks you to enter the boot password to continue. The following section
describes how to do this. The BIOS then loads the operating system, either - MS
DOS, Windows 98SE, OS/2 or NetWare, etc. - from the hard disk (or floppy disk if
one is inserted in Drive A:). The computer is then ready for use.
39
Vig535b Motherboard Manual