CMOS is an abbreviation for Complementary Metal Oxide Semiconductor. CMOS technology is used in microprocessors, microcontrollers, static RAM, and other digital logic circuits. CMOS technology is also used for several analog circuits such as image sensors (CMOS sensor), data converters, and highly integrated transceivers for many types of communication.
CMOS uses a complimentary arrangement of NMOS and PMOS, Negative And Positive Metal Oxide Transmitter Circuits. CMOS memory draws very little current (Nano-amps). Values stored in it can be maintained for very a long period of time while the computer is off with a rechargeable lithium battery. The CMOS memory is used to store system configuration information, such as disk drive parameters, memory configuration and setup program.
CMOS memory is used by the basic input output system (BIOS), a program permanently stored in the flash memory as disk drive parameters, memory configuration, and the date-time, some of which we enter in the CMOs setup program. CMOS setup is part of the BIOS program.
The CMOS memory is usually located with the real-time clock in the motherhood chipset or in a separate real-time clock chip. It is located in the chipset on most recent motherboards.