Short for
complementary metal oxide semiconductor. Pronounced
see-moss, CMOS is a widely used type of
semiconductor. CMOS semiconductors use both NMOS (negative polarity) and PMOS (positive polarity) circuits. Since only one of the circuit types is on at any given time, CMOS chips require less power than chips using just one type of
transistor. This makes them particularly attractive for use in battery-powered
devices, such as
portable computers.
Personal computers also contain a small amount of battery-powered CMOS
memory to hold the date, time, and
system setup parameters.