CMOS

Because of the initial cost of Complementary Metal Oxide Semiconductor (CMOS) technology, memory, transistors, and large parts of most microprocessors were once reserved for storing the startup configuration of the PC. With technology advances and lower costs, however, CMOS (pronounced "sea moss") technology is now used throughout the PC. CMOS memory requires only about one millionth of an amp to hold any data stored on it. Using only a lithium battery, CMOS memory is able to store the startup configuration of a PC for many years. The term CMOS is still synonymous with the PC's startup configuration data.