BIOS (Basic Input/Output System):
- Most of us are not aware of what the BIOS is and what it does?
- Remember that it is just a firmare not a hardware
- It comes pre-installed when you buy a computer
- It is also called as Built-In Operating System
Where it is stored?
- It is stored in the Read-Only Memory(ROM) of the computer.
- More specifically, it is located in the Erasable Prgrammable Read-Only Memory(EPROM) chip located in the motherboard of the computer.
Why it is needed?
- When you power on your computer, microprocessor tries to execute its first instruction
- But it has to get instruction from somewhere
- It cannot get it from Operating System because OS is located in the hard disk
- Microprocess cannot able to access instructions in the hard dist until someone tell how to access it
- So who will tell those instructions???
- Correct, BIOS provide those instructions.
What it does?
- Retrieve custom settings from CMOS
- Loads Interrupt Handlers and Device drivers
- Initialize registers and Power Management
- Run Power-On Self-Test(POST)
- Display System Settings
- Determining Bootable Devices
- Initiate Bootstrap sequence
