I have a project High Speed with a locked MPU. The MPU is NOT an original 11, but is instead an 11a (5764-12091-00). I purchased a new pair of ROMs for U26 and U27 and they test good in a friend's HS with an original Sys 11-nothing MPU. They are burned to a 2764 at U26 and a 27256 at U27, which I believe is the same setup as the original ROMs.
My question: Do I need a pair of 27256 ROMs (both U26 and U27) for them to work in the 11a MPU? I have an 11b MPU from a working Jokerz and the known-to-be-good HS ROMs will NOT boot in it. When I put the working Jokerz ROMs (both 27256) in the locked 11a MPU, it gets closer to booting.