What is the difference between BIOS and CMOS?

BIOS and CMOS often times thought to be the same, but they are not. They are two different components of the computer, but they work together to make your computer function properly.

BIOS is a computer chip on the motherboard, which resembles the picture to the right. This chip

contains a special program that helps to interact with the computer's processor and control other components in the computer. These other components include disk drives, video cards, sound cards, network cards, disk drives, ports, USB, hard drives and more. Without the BIOS, the processor will not know how to interact or interface with computer components, and computer will not function.

The CMOS is also a computer chip on the motherboard, but more specifically, it is a RAM chip. This is a type of memory chip which stores information about the computer components, as well as settings for those components. However, normal RAM chips lose the information stored in them when power is no longer supplied to them. In order to retain the information in the CMOS chip, a CMOS battery on the motherboard supplies constant power to that CMOS chip. If the battery is removed from the motherboard or runs out of juice (eg a dead CMOS battery), the CMOS would lose the information stored in it. Any settings you made in the CMOS setup would be lost, and you would need to make those settings changes again after a new CMOS battery was put on the motherboard. For example, with a dead CMOS battery the time and date will reset back to the manufactured date if it has been off for a long period of time....

The BIOS chip, the BIOS reads the information from the chip CMOS, when the computer is started during the boot process before. You may notice on the first launch of the screen, the screen is called the POST, the option is available to enter the BIOS setup or CMOS. When you enter this settings area, you enter settings CMOS, instead of setting BIOS. BIOS chip and the software can not be updated directly by the user. The only way to update the BIOS use the BIOS flash update program called BIOS, which updates the BIOS to a different version. These updates are usually provided either by the motherboard manufacturer or computer manufacturer.

CMOS setup allows you to change the time and date and the settings for the devices are loaded at startup, as hard drives, floppy drives and disk drives. CMOS setup allows you to enable and disable various hardware devices, including USB ports, on-board video and sound card (if any), parallel and serial ports, and other devices.

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