its what tell the computer what to boot first, it can be anything choosen by the bios, if you go into the bios you can change the boot order.
The BIOS stores instructions for how the computer is supposed to boot up.
bios
A CD-ROM drive is not needed to boot the computer. Just put the hard drive first in the boot order in the BIOS.
BIOS setup
Set the BIOS boot order to include the CD. You can change the BiOS when you start the computer, usually something like the key will go to BIOS instead of the boot partition.Don't fool around with things you don't understand, but you should be able to find the settings that deal with boot order. Put the CD BEFORE the C drive, then if there is a bootable CD in the drive the computer will try to boot from there.I can't give more detailed instructions than that because so many of the BIOS screens are unique. But you should be able to read about the BIOS in the documentation that came with your motherboard.
Once your computer boots into BIOS, you need to search around and turn off the option that is telling it to boot to BIOS automatically. Frances
BIOS provides the boot-up process for a computer. It is part of ROM.
it uses bios first to boot when you start up you see dependind on the computer a bios screen witch is on the mother board you can update you bios, but make sure because its a risky move if its not nessesary dont update bios unless its needed back up your computer before you do this
If the BIOS supports it, you can. You'll either have to go into BIOS and change the boot order or some computers will let you press F10 or F12 during boot up to display a boot menu that will let you choose from which disk you'd like to boot.
BIOS is looking for a boot sector. If the disk does not have a valid boot sector at the address which is also known by the BIOS, it won't boot from disk.
If you have an install CD, you can start the computer with this. Set your BIOS up to boot from CD, restart the computer with the disk in the drive and follow the onscreen instructions to install Windows XP. Please ask a separate question if you wish to know how to change the Boot order for your BIOS.
BIOS