Re: Whats the diff between CMOS and BIOS?....

The BIOS is the basic I/O system which is stored in an EEPROM when you start your computer, a copy is loaded into a few small SRAM chips that keep power by means of the CMOS battery and even when the computer is shut down will retain the checksum of your last POST.

If you short the "Clear CMOS" the power to the SRAM is interrupted and the transistors flip back to 0. On the next bootup, depending on the make and model you either get a checksum error (normal), and you have to enter the Setup and save again or else it just takes what it got and loads it automatically. BTW, metal oxide semis are transistors which are the building blocks of SRAM.