CMOS is the term commonly used to describe the small amount of memory on a computer's motherboard that stores settings. BIOSSome settings include: BIOS These are the system time and date, as well as hardware settings. Below, we'll answer the question: What is CMOS and what is its purpose?
Note: CMOS image sensor – used by digital cameras to convert images into digital data – is different.
Other names for CMOS
CMOS (clearly see-moss) by its full name: Complementary Metal-Oxide Semiconductor. However, it is sometimes referred to as Real-Time Clock (RTC), CMOS RAM, Non-Volatile Random-Access Memory (NVRAM), Non-Volatile BIOS Memory, or Complementary Metal-Oxide Semiconductor (COS-MOS).
Note: CMOS is also an abbreviation for other terms unrelated to what is discussed on this page, such as Cellular Management Operating System and Comparison stands for Points of View.
Clear CMOS
Most talk about CMOS involves clearing the CMOS, which means resetting the BIOS settings to their defaults. This is a really easy task and a great troubleshooting step for many types of computer problems.
For example, your computer might beFreeze during POST In this case, clearing the CMOS to reset the BIOS settings to factory default levels may be the easiest solution.
Or you may need to clear the CMOS to reset incorrect BIOS settings to fix some hardware-related error messages, such as: Code 29 errorsOther CMOS errors revolve around low battery voltage, CMOS test, battery failure, and read error.
How BIOS and CMOS Work Together
BIOS is a computer chip on the motherboard like CMOS, except its purpose is to communicate between Healer and other hardware components such as hard disk drive وUSB ports وsound card وvideo card And more. Without a BIOS, a computer won't understand how these parts work together.
The BIOS firmware is also what performs the Power On Self Test to test these pieces of hardware, and what ultimately triggers the bootloader to boot the operating system.
CMOS is also a computer chip on the motherboard, or more specifically a random-access memory (RAM) chip, which means it will normally lose the settings it stores when the computer is turned off (just as the contents of RAM aren't retained each time you restart your computer). However, the CMOS battery is used to provide constant power to the chip.
When your computer first boots up, the BIOS pulls information from the CMOS chip to understand hardware settings, the time, and anything else stored there. The chip typically stores 256 bytes of information.
What is a CMOS battery?
CMOS is usually powered by a coin-sized CR2032 cell battery, referred to as a CMOS battery.
Most CMOS batteries will last the lifetime of the motherboard, up to 10 years in most cases, but occasionally they will need to be replaced depending on how the device is used.
An incorrect or slow system date and time, along with missing BIOS settings, are key signs of a dead or dying CMOS battery. A red light on the motherboard may be another indicator of a dead CMOS battery.
Replacing a CMOS battery is as easy as swapping out the dead one for a new one. You can get a new CMOS battery from Amazon and other retailers that sell computer parts.
More about CMOS and CMOS batteries
While most motherboards have a place for the CMOS battery, some smaller computers, such as many tablets and laptops, have a small external battery compartment that connects to the motherboard via two small wires.
Some devices that use CMOS include microprocessors, microcontrollers, and static random access memory (SRAM).
It's important to understand that CMOS and BIOS are not interchangeable terms. While they work together to perform a specific function within your computer, they are two entirely different components.
When your computer first boots up, there's an option to boot into the BIOS or CMOS. Opening the CMOS setup allows you to change the settings it stores, such as the date and time and how various computer components first start up. You can also use the CMOS setup to disable/enable certain hardware devices.
CMOS chips are desirable for battery-powered devices such as laptops because they use less power than other types of chips. Although they use both negative and positive polarity circuits (NMOS and PMOS), only one type of circuit is powered at a time.
The Mac equivalent of CMOS is PRAM, which stands for Parameter RAM. You can also reset your Mac's PRAM.
Frequently Asked Questions:
Q1: What are the typical symptoms of CMOS battery failure?
The answer: Many problems can be associated with a CMOS failure. For example, your laptop may have difficulty booting, cannot connect to the internet, or beeps constantly. Other symptoms include missing drivers, unresponsive peripherals, and a reset date and time.
Q2: What is CMOS test error?
The answer: A CMOS checksum error is a conflict between the CMOS and BIOS during boot-up. You can fix this error by following several troubleshooting steps, including restarting your computer, downloading and flashing a BIOS update, resetting the BIOS, and possibly replacing the CMOS battery.
