How does the computer know the mac address of peripheral devices such as flash drives and Ipods?

I'm studying how newer computers package data even internally to send and receive information. From what I understand, the CPU packages data and sends it through the expansion bus to devices that are plugged into the computer (even CD roms). I'm uming it uses each device's mac address to know where the data goes. My question is if there is a table or register somewhere that lists the mac addresses of all devices attached (even plug and play)? Basically, I'm hoping there's a table similar to an ARP table, but using something other than IP for devices connected to the expansion bus rather than the internet. Is there? If not, how doe the computer know the mac address of plug and play devices?