what do you mean by BIOS and CMOS set up?how are they useful?
Definition: Basic Input/Output System (BIOS)
The BIOS chip uses EEPROM (Electrically Erasable Programmable Read-Only Memory) to be able so store the information contained in the BIOS software. This type of memory permits us to be able to later upgrade our BIOS to a newer version. The BIOS works in conjunction with the CMOS chip where the information from the BIOS settings is saved.
How it works:
When you turn the power ON on the computer, before your CPU can start loading your operating system, it needs to know what peripherals are available and what options your computer has. To be able to obtain all this information, the BIOS need to take over and begin it's tasks. Once all the BIOS's tasks are completed without any errors, the computer then goes on to boot up the operating system to be able to run normally. This is when you here the notorious beep, meaning your computer is working well according to your BIOS.