CMOS

Also known as a Real Time Clock (RTC), Non-Volatile RAM (NVRAM) or CMOS RAM, CMOS is short for Complementary Metal-Oxide Semiconductor. CMOS is an on-board semiconductor chip powered by a CMOS battery inside computers that stores information such as the system time and system settings for your computer. A CMOS is similar to the Apple Macintosh computer's PRAM. To the right is an image of a CMOS battery on a computers motherboard.

• Information about entering CMOS setup can be found on document CH000192.
• See our CMOS help page for additional help and information about CMOS.

Also see: MOS, Motherboard definitions, PRAM, Quartz crystal, RTC