I still not so clear between BIOS and CMOS.
If I understand for my opinion, BIOS is a chip store firmware to make all hardwares components communicate with each other and it's can't be change, mean it's working as ROM.. but it can be update or replace the chip.
And CMOS, I didn't understasnd as well because before I thought that, CMOS is hardware and bios is software..
Can you explain me the both?
The BIOS and CMOS are often times thought to be the same thing, but they are not. They are two different components of a computer, but they do work together to make the computer function properly.
The BIOS is a computer chip on the motherboard. This chip contains a special program that helps the computer processor interact and control the other components in the computer. Without the BIOS, the processor would not know how to interact or interface with the computer components, and the computer would not be able to function.
The CMOS is also a computer chip on the motherboard, but more specifically, it is a RAM chip. This is a type of memory chip which stores information about the computer components, as well as various settings for those components and other variables. CMOS allows you to change date/time and startup boot order etc. When you access "BIOS" on startup, you're actually accessing the CMOS because as you stated the BIOS cannot be changed directly, only by performing BIOS updates.
The BIOS program on the BIOS chip reads information from the CMOS chip when the computer is starting up, during the boot up process.
In short, the BIOS allows the processor to control things such as HDD, CDROM etc. Whereas, the CMOS is the information which determines what these components do and can be modified by a user.
Thanks you so much for your great explaining!
If I don't care about CMOS, I will understand well about BIOS without any doubt.. but when I read about CMOS, it's very very similar..So please let me ask that,
If we talk about BIOS mean a chip located on Motherboard and it is functions to make all hardware components interacts with each other..
So if when we go to BIOS setting , we do some configuration as change boot devices and save it... so the one who store saved configuration is CMOS that right?
if CMOS fail battery everything that changed will be fail too?
That is correct. The CMOS Config is saved by the CMOS battery powering the chip. If the battery dies the CMOS is lost and you normally get on POST something along the lines of "press F1 to load default configuration"
One more question but still inside the same BIOS,
If CMOS fail battery, BIOS configured setting will be reset or fial..
But why on my nephew's laptop, when she forget bios passwords password and she tried to take out the CMOS battery, why BIOS still hold on the password?