Nonvolatile BIOS memory
（重定向自CMOS Battery）
![CMOS battery in a Pico ITX motherboard](/Images/godic/202501/05/Bottom_EPIA_PX10000G_Motherboard_new5744.jpg")
![Type CR2032 button cell, most common CMOS battery.](/Images/godic/202501/05/Battery-lithium-cr20325744.jpg")
Nonvolatile BIOS memory refers to a small memory on PC motherboards that is used to store BIOS settings. It is traditionally called CMOS RAM because it uses a volatile, low-power complementary metal-oxide-semiconductor (CMOS) SRAM (such as the Motorola MC146818 or similar) powered by a small "CMOS" battery when system and standby power is off. The typical NVRAM capacity is 256 bytes.