When in the context of computing, CMOS refers to a chip which stores information about your PC. Including the time, the date and various configuration data relating to your PC's configuration.

The CMOS device is backed up by a battery so the information can be retained when the system is switched off.

CMOS technology has a very low power consumption, which makes it ideal for this type of application where minimal power consumption is critical for sustaining a longer battery life.

The information (typically 64 Bytes) in the CMOS device is accessed by the BIOS when the machine is booted up (turned on). The CMOS settings (information) can be changed by the user by way of a setup program, usually accessed with a key sequence when the machine is first booted up.

Different systems use different keys or key sequences to access the CMOS settings (BIOS settings). You can find out the key sequence for your particular system from either the manual that came with your machine, or your motherboard manual. It may also be noted on the startup screen as the machine is first turned on, look for something along the lines of "press F2 to enter setup". Some typical keystrokes to get into the BIOS settings include pressing the DEL key, or the F2 key.

Back to Computer Dictionary