BIOS (Hardware & Software)

• Basic Input Output System. 
• Disimpan di dalam flash memory (ROM chip). 
• Memastikan seluruh komponen Komputer bekerja dengan baik. 
• Special software that interfaces hardware with the OS.

Apa yang dikerjakan oleh BIOS:

• The BIOS software has a number of different roles, but its most important role is to load the operating system. 
• When you turn on your computer and the microprocessor tries to execute its first instruction, it has to get that instruction from somewhere.
• It cannot get it from the operating system because the operating system is located on a hard disk, and the microprocessor cannot get to it without some instructions that tell it how.
• The BIOS provides those instructions.
• A power-on self-test (POST) for all of the different hardware components in the system to make sure everything is working properly
• Activating other BIOS chips on different cards installed in the computer - For example, SCSI and graphics cards often have their own BIOS chips.
• Providing a set of low-level routines that the OS uses to interface to different hardware devices - It is these routines that give the BIOS its name. They manage things like the keyboard, the screen, and the serial and parallel ports.
• Managing a collection of settings for the hard disks, clock, etc.

Sequence

• Check the CMOS Setup for custom settings
• Load the interrupt handlers and device drivers
• Initialize registers and power management
• Perform the power-on self-test (POST)
• Display system settings
• Determine which devices are bootable
• Initiate the bootstrap sequence