Many peoples think that the BIOS and CMOS are the same thing, but actually they are different things. Both are two different components of computer, but they work together to make the computer function properly. Some difference between CMOS and BIOS are described below.

Basic Input Output System (BIOS) :-

The BIOS is a special type of firmware which is stored in a chip inside your computer. It is the first program which runs every time when you turn on your computer.

The BIOS performs the Power On Self Test (POST) which initializes and tests the computer hardware. Then it runs Boot loader of system or loads the OS directly.

When you start a computer you may see a message like “Press F2 for setup” this setup is BIOS configuration interface.

Complementary Metal Oxide Semiconductor (CMOS) :-

Every time when you make change in your BIOS configuration the settings are not stored on BIOS chip. They are stored on a special type of chip which in known as CMOS chip. CMOS is also called as Real Time Clock (RTC) and non-volatile RAM.

CMOS is also a computer chip on mother board which needs constantly power to work this power is provided by CMOS Battery. When the computer first boots up, BIOS pulls information from the CMOS chip to understand the hardware settings, time and date, and anything else that stored in it.

Comparison Between BIOS and CMOS