Complementary Metal Oxide Semiconductor
Complementary Metal Oxide Semiconductor(CMOS) is a small portion of battery powered memory on the motherboard that contains system settings like types of drives, device types in the system, which drive to start up from etc. The battery used is a 3volt battery. CMOS and BIOS are often interchanged although they are different things. Think of the BIOS as the skeleton frame upon which the CMOS settings hang. All computer memory forgets everything it holds when power to it is shut off. If the power was totally shut off to your CMOS, your computer would forget its start up settings, and you’d have to re-enter these settings every time you started your computer! Fortunately this is not the case as your CMOS always receives enough power to remember its settings, even when your computer is off. How? It is powered by a small lithium battery on your motherboard. Lithium batteries are designed to last years, and often outlive the usefulness of the computer they reside in. If you keep a computer l...