Learning Objectives

Initialize registers and power management

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• Once finished, it begins searching for a drive to boot an operating system → the boot order or sequence
• Depending on the BIOS setting, the procedure may try to access (in a predefined, customizable order) the first sector (boot sector) of any floppy disk, any hard disk, and any CD-ROM in the system.
• BIOS will try to initiate the boot sequence from the first device.
• If it does not find the proper files in the device, the startup process will halt and an error message is displayed.

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• Most are set to first look for a bootable floppy disk, and if one is not found then proceed to a hard disk, which is usually the C: drive.
• Once the drive is identified, it looks for boot information to start the operating system boot process.
• If it is searching a hard disk, it looks for a master boot record (MBR) at cylinder 0, head 0, ‘sector zero’, the first sector on the disk.
• If a Master Boot Record is found, it is read into memory at location 0000:7c00 and INT 19 jumps to memory location 0000:7c00.
• At this point, the BIOS attempts to move control of the computer from the BIOS to the actual operating system.

Configuring BIOS - CMOS Setup

• During the initial start up or the boot sequence, you will notice a sentence

Press ____ to Enter Setup. Most system use Esc, Del, F1, F2 or combination of keys to enter Setup menu.

• This will cause the boot process to be diverted into the CMOS configuration. CMOS contains stored configuration regarding how the system is to be booted.

• It is configuration program that allows you to configure hardware settings including system settings such as boot sequence, computer passwords, time and date.

AN EXAMPLE OF A CMOS SETUP