What’s CMOS?

You have probably heard the word CMOS, but do you recognize what it’s? Let’s solve it in this text.

First, let’s discover what BIOS is and what it does in your computer or laptop. BIOS stands for Basic Input/Output System. It’s a program that ensures that the pc starts and runs until the operating system is loaded. In itself, it is just a set of instructions stored in the pc’s read-only memory (ROM) situated on the motherboard. Nevertheless, if the BIOS only had everlasting memory, its capabilities can be limited to the parameters that were hard-coded when the BIOS chip was manufactured, and users wouldn’t have the opportunity to make changes to BIOS settings.

Not with the ability to change settings in your computer can be very inconvenient. To unravel this problem, a special BIOS-related CMOS memory was created to store system settings, especially those entered by the user through the BIOS Setup interface. At the identical time, the entire amount of BIOS CMOS memory is amazingly small – only 256 bytes!

CMOS manufacturing technology and its history

What’s the difference between CMOS memory and other forms of memory? Abbreviation CMOS means a complementary semiconductor with a metal oxide. This memory has low energy consumption, so it may possibly store data for a very long time.

CMOS technology has a protracted history, and any such memory, called CMOS RAM, was first introduced in 1963. It was relatively expensive on the time, but it surely had many benefits. Although any such memory is slower than conventional RAM, it uses less electricity and generates less thermal energy (heat) during operation.

Storing data in BIOS doesn’t require high speed, but the quantity of power consumed during this task should ideally be as little as possible, so CMOS memory is best suited on this case.

Within the half century since its discovery, CMOS technology has been greatly improved. Now CMOS RAM chips are utilized in most computer components, even the processor itself. Furthermore, this technology is just not only utilized in computers. Chips of this kind are also widely utilized in photosensitive elements (matrices) of devices comparable to scanners and digital cameras.

Work

Although this memory uses little power, a reliable power source continues to be required. Specifically, a special RTC CMOS battery is used to power the BIOS memory in periods when the pc is turned off. The battery lasts roughly 3-5 years and have to be replaced to keep up memory content. Most manufacturers provide quick access to the battery, so it may possibly get replaced in a matter of minutes.

Application

CMOS memory is a small but very essential a part of the BIOS. The sleek operation and lifetime of the complete computer will depend on this one tiny battery. Within the event of a battery failure, the BIOS loses configuration settings and restores factory settings. This will cause a lot of problems, including: incorrect time and date, difficulty starting the pc, and random resets. In some cases, a damaged CMOS battery may also result in data loss. Should you suspect that the CMOS battery has turn out to be damaged, it will be important to interchange it as soon as possible. Fortunately, CMOS batteries are relatively inexpensive and straightforward to interchange, but do not forget that manufacturers have different connectors, cable lengths, battery types and part numbers. For instance, the RTC battery for Lenovo ThinkPad Yoga has a component number 00HN933 and almost definitely this battery is not going to work with one other laptop. In any case, it’s best to seek the advice of the motherboard documentation or check the part variety of the unique battery. You may also contact a specialized CMOS battery manufacturer, e.g this, and ask to envision the battery by computer model number. After inserting the brand new battery, the pc should function normally again.