To give some background, the reason I want to know this information is because, I recently bought a brand new SSD to place into a 2009 Mac mini, where I want to install Kubuntu. I know that PCs store their BIOS in the motherboard ROM, but not entirely sure for Macs.
The problem I have is that if I swap the internal HDD (without copying data to the new SSD) in the Mac, will it mean I can't boot from USB when I have swapped out the hard drive, as the USB boot menu will be wiped, or is this menu stored somewhere else, meaning that I can still access it without copying my hard drive data to the new SSD?