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Power to the Computer


The first thing that happens when you turn an Intel  PC on is that the  BIOS executes. BIOS  stands for Basic Input/Output System. It's a program permenantly stored in the computer on read-only chips, normally. For our purposes, the BIOS can never be changed. It performs some minimal tests, and then looks for a floppy disk in the first disk drive. If it finds one, it looks for a ``boot sector'' on that disk, and starts executing code from it, if any. If there is a disk, but no boot sector, the BIOS will print a message like:


Removing the disk and pressing a key will cause the boot process to continue.

If there isn't a floppy disk in the drive, the BIOS  looks for a master boot recordmaster boot record   (MBR) on the hard disk. It will start executing the code found there, which loads the operating system. On systems, LILO , the LInux LOader, can occupy the MBR position, and will load . For now, we'll assume that happens and that starts to load. (Your particular distribution may handle booting from the hard disk differently. Check with the documentation included in that distribution. Another good reference is the LILO  documentation, [1].)

Converted on:
Mon Apr 1 08:59:56 EST 1996