Bios, which is also known as Basic Input Output System is actually the first program which the processor comes across and accesses to make sure that all the other components such as hard drives, peripherals, ports, central processing unit and other basic programs are under good condition and are working. It is accessed during the start up of the system.

Many people still are not aware that the operating system is completely different from the BIOS. Operating system is located in the hard drive and it offers the user, the interface that occurs and can be viewed by the user when he firsts starts the computer. On the other hand, the BIOS which is Basic input Output System is located in a flash memory chip or Read Only Memory which is also known as ROM inside the motherboard. BIOS happens to be the primary and basic necessity at the time of booting the personal computer. Its main function is to load the operating system though it has many other functions. Further, when the computer is activated, it offers the first instructions to the microprocessor. The usual sequence of the BIOS program during start up begins with checking the CMOS setup for any customized settings, loading the device drivers and interrupt handlers of various computer hardware.