how companies flash BIOS for the first time on motherboard

I mean when a company have the product right now it’s juts some metal how they put a software inside it?
Answer #1
My understanding is that they use a CPU that is supported by the current BIOS(mobo will have a pre-installed BIOS from manufacturer (how they do it I don’t know)), then flash it to support the new CPU (Without a CPU it won’t post, unless certain boards have that capability now).
Answer #2
Bios is the answer…It is all there and mainly programmed up when you buy the Mobo..
All you have to do is set the clock and “tune” it up to suite you configuration.
The chips would normally be flashed by the specialised Bios companies ,like AmiBios, before being assembled on the motherboard.
http://computer.howstuffworks.com/bios1.htm