What is Computer BIOS? Use of BIOS in Computer

If you have a personal computer where you spend most of the time in running personal and business tasks then you must have a little understanding of BIOS. This article also helps you if you are preparing for computer-related jobs like Computer Operator or Computer Officer.

BIOS is a huge topic, covering each and every piece of information about BIOS in a single article is not possible. Don’t worry I have covered the core information of BIOS so that you can know the meaning of BIOS, what is its role in booting and how the BIOS helps in starting a computer.

Basic Input Output System or simply a BIOS in computers is a built-in component which acts as an interface between Operating System and other hardware devices including Motherboard. BIOS is a firmware consisting of instructions that are programmed during manufacturing and can’t be rewritten. BIOS is stored in ROM (Read-Only-Memory).

In computer terminology, BIOS is mainly used in the booting process when the computer is turned on or restarted. Booting is the process of loading system and program files or data from secondary storage devices to main memory. There are two kinds of booting methods: warm booting and cold booting. The booting method that is used when a computer is turned on from the OFF position is known as cold booting. Warm booting occurs only when a computer is restarted. 

Booting process involves the various instructions that are needed while loading files into main memory (or starting a computer). All those instructions are programmed into BIOS permanently.

BIOS performs actions based on the POST method. In computing, POST refers to Power On Self Test. BIOS uses POST to check whether the hardware is functioning properly and also checks if all the necessary hardware devices are present.

While starting a personal computer, the major responsibility of BIOS is to check whether the Operating System is present on the hard drive. If BIOS finds the Operating System files on the hard drive, it starts loading all the necessary files associated with the Operating System from the hard drive into RAM (Random Access Memory).

Access BIOS in your PC:

As you know BIOS can’t be rewritten but you can configure the BIOS to perform several tasks. You can configure the BIOS using the BIOS setup dialog box. If you want to access the BIOS setup dialog box, first restart your computer and press F2, F1, F10 or F3 key before the computer starts booting.

Remember the keystroke used to access the BIOS configuration can be different in different models of computers.


Similar to the BIOS, CMOS is another major component that is responsible for holding some built-in instructions. Complementary Metal Oxide Semiconductor or simply a CMOS is a non-volatile memory of BIOS. 

The CMOS chip works continuously even if your computer is in powered off state, this means CMOS works without electric power.

In computers, the main function of a CMOS chip is to make your computer’s date and time upto date. I am sure you have noticed that if you turned on your computer after one or several months, your computer displays the current date and time. 

If your BIOS version is not up to date, your PC may run into problems while booting or the Input/Output devices connected to your PC might not perform properly. 

That’s why you should frequently check the BIOS version and install the new BIOS if the version is running out.