What is the typical form factor of a battery powering the CMOS memory?

The typical form factor of a battery powering the CMOS memory is the CR2032. This coin-cell battery is commonly used in motherboards to maintain power to the CMOS chip, which stores BIOS settings and system configurations when the computer is powered off. The CR2032 battery has a diameter of 20 mm and a thickness of 3.2 mm, making it compact enough to fit on motherboards while providing the necessary voltage and longevity for CMOS memory.

The choice of the CR2032 is based on its balance of size and energy capacity, ensuring that it can maintain the small amount of power required for CMOS operations over long periods, usually several years. This is crucial for the retention of BIOS settings, such as system time, date, and hardware configurations.

In contrast, options like AA and AAA batteries are typically intended for larger devices that require more power and would not be suitable for the low-power needs of CMOS memory. The 9V battery is used in specific applications that demand higher voltage and is also unsuitable for powering CMOS. Thus, the CR2032 is the standard choice for this purpose.