Sony C-mos Battery Cr- 2032CMOS (complementary metal-oxide-semiconductor) is a chip on the motherboard that contains BIOS configuration, date, time and other information that the computer needs during startup. Normally, this information would be lost when the computer is shut down or loses power for some reason (dead battery, power failure, etc.). The CMOS battery supplies power to the CMOS chip, even when the computer is shut down. This battery is usually a watch type batter which can supply power for a year or more.