BIOS functions in CPU

Basic input/output system

Every desktop and laptop computer in common use today contains a microprocessor as its central processing unit. The microprocessor is the hardware component. To get its work done, the microprocessor executes a set of instructions known as software

     The operating system - The operating system provides a set of services for the applications running on your computer, and it also provides the fundamental user interface for your computer. Windows 98, Xp , win 7  and Linux are examples of operating systems.

     The applications - Applications are pieces of software that are programmed to perform specific tasks. On your computer right now you probably have a browser application, a word processing application, an e-mail application and so on. You can also buy new applications and install them. 

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. Some of the other common tasks that the BIOS performs include:
   1. Check the CMOS Setup for custom settings
   2. Load the interrupt handlers and device drivers
   3. Initialize registers and power management
   4. Perform the power-on self-test (POST)
   5. Display system settings
   6. Determine which devices are bootable
   7. Initiate the bootstrap sequence