What is the BIOS?

- Ladies and gentlemen,…I present to you a typical motherboard.…Now, if you take a look at this motherboard,…the motherboard is really an assumption.…The motherboard assumes that you're going to be using…a lot of peripherals for your computer.…It assumes it so well that it actually…even makes connections for them.…They assume you're gonna use video,…they assume you're gonna use keyboard,…they assume you're gonna use a mouse.…There's connectors on here for hard drives…which they assume you're going to use.…Now, these are pretty safe assumptions, don't get me wrong,…but the bottom line is that you've got…all of these peripherals.…

Now, when a connection comes in,…let's pick on the keyboard for a minute,…so we plug the keyboard into this little PS2 connector,…so when you press down the letter J on the keyboard,…a scan code goes though the keyboard itself,…goes through the cabling,…goes into here,…and then it's stored on a chip.…Now the computer needs to have some way to query that chip,…which we call the keyboard controller,…