What is CMOS?

CMOS, short for Complementary Metal Oxide Semiconductor, is a low-power, low-heat semiconductor technology used in contemporary microchips, especially useful for battery-powered devices. The specific technology is explained in detail on this CMOS definition page.

Most commonly, though, the term CMOS is used to refer to small battery-powered configuration chips on system boards of personal computers, where the BIOS stores the date, the time, and system configuration details.

Also see:

• On a PC, how do I reset or remove the CMOS password?
• What is BIOS?
• What's the difference between BIOS and CMOS?