What is the purpose of the CMOS RAM on a motherboard?
CMOS (complementary metal-oxide-semiconductor) is the term usually used to describe the small amount of memory on a computer motherboard that stores the BIOS settings.
CMOS is Complementary metal-oxide semiconductor, or CMOS, typically refers to a battery-powered memory chip in your computer that stores startup information. Your computer'sbasic input/output system (BIOS) uses this information when starting your computer.
- CMOS technology is used in microprocessors, microcontrollers, static RAM, and other digital logic circuits. CMOS technology is also used for several analog circuits such as image sensors (CMOS sensor), data converters, and highly integrated transceivers for many types of communication.
- The CMOS is a physical part of the motherboard: it is a memory chip that houses setting configurations and is powered by the onboard battery. The CMOS is reset and loses all custom settings in case the battery runs out of energy, Additionally, the system clock resets when the CMOS loses power.
- CMOS (complementary metal-oxide semiconductor) is the semiconductor technology used in the transistors that are manufactured into most of today's computer microchips. Semiconductors are made of silicon and germanium, materials which "sort of" conduct electricity, but not enthusiastically.
The motherboard's battery is used for low-level system functions like powering the real-time clock and storing a computer's BIOS settings. On newer computers, the battery may only be used for the clock.
- Here are some tell-tale signs that your battery is dying:
- Invalid configuration will appear on your screen.
- Run Setup appears on your screen.
- Press F1 to continue appears on your screen.
- Invalid drive specification appears on the screen after you've pressed F1.
- Clock Error or Clock Message appears on your screen.
- Traditionally, BIOS settings were stored in CMOS RAM, which was powered by a battery when the computer was powered off. The battery was necessary because the settings would be lost if all power was lost, just as the data in your computer's RAM is lost when it loses power.
- 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.
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.
- A computer's Basic Input Output System and Complementary Metal-Oxide Semiconductor together handle a rudimentary and essential process: they set up the computer and boot the operating system. The CMOS's primary function is to handle and store the BIOS configuration settings.
- Steps to clear CMOS using the battery method
- Turn off all peripheral devices connected to the computer.
- Disconnect the power cord from the AC power source.
- Remove the computer cover.
- Find the battery on the board.
- Remove the battery:
- Wait 1–5 minutes, then reconnect the battery.
- Put the computer cover back on.
- Types of memory that retain their contents when power is turned off. ROM is nonvolatile, whereas RAM is volatile. This term often refers to the CMOS memory in PCs that holds the BIOS.
Updated: 17th October 2019