Are firmwares interchangeable????

[packer]

Say for instance,i put a plextor cdrw firmware on a sony cdrw, will it work or break the burner?
if so can you put very early firmware of plextor (v1.01 which can copy sd2, read in other forums if you downgrade the firmware you can do it) on a drive that can't do it because of its firmware??????

Thanks!!