I realize at the time it wasn't very easy for most people but a computer that often receives upgrades via ROM is the Atari ST. I (sort of) recently upgraded my

I realize at the time it wasn't very easy for most people but a computer that often receives upgrades via ROM is the Atari ST. I (sort of) recently upgraded my 1040. I bet one could produce DOS 6.22 replacement ROMs for the Tandy!