CMOS
Alternatively referred to as a Real-Time Clock (RTC), Non-Volatile RAM (NVRAM) or CMOS RAM, CMOS is short for Complementary Metal-Oxide Semiconductor. CMOS is an on-board semiconductor chip powered by a CMOS battery inside computers that stores information such as the system time
and date and the system hardware settings for your computer. A CMOS is similar to the Apple Macintosh computer's PRAM.
In the picture to the right, is an image of a CMOS battery on a
IBM compatible computers motherboard and the most common CMOS battery you're likely to encounter with your computer.
In
the
bottom right picture, are examples of batteries that may be used in a computer to power the CMOS memory. As mentioned above the most common battery is the coin cell battery (lithium battery), usually about the size of a U.S. Nickel.
The standard lifetime of a CMOS battery is around 10 Years. However, this can vary depending on the use and environment that the computer resides.
- How to enter the BIOS or CMOS setup.
- How to replace the CMOS battery.
- Computer CMOS help and support.
Also see: BIOS, MOS, Motherboard definitions, PRAM, Quartz crystal, RTC