How does S/PDIF Digital Audio work?

[vidya]

Hey, I was wondering how the hell does S/PDIF Digital Audio work and how does it remember exactly what % volume it should be on a motherboard?
I don't have any speakers, just a keyboard and mouse and I've, reset BIOS, reformatted and reinstalled windows 7 disc and the S/PDIF still remembers what volume % it was on before all of that, how is it remembering this?

I'm just curious how it knows.

 

[fireberd]

Because the chip on the motherboard stores the info, it's not software.