Originally Posted by Toni Wilen

Thanks. "Unfortunately" it seems MK I and MK II have identical ROM (Your rom image is exact same as MK II rom image) and probably also nearly identical hardware.



Perhaps some kind of "special" access (for example unaligned long access that hits both "banks") was not handled correctly?

Boot ROM won't help with this (ROM code "only" tries to find RAM config that makes total RAM single contiguous address range), problem is in logic chips.