I tried to play "Escape from M.O.N.J.A.S.", but the game hangs at the very beginning, when it should show the main menu. I suspect that the problem is that it doesn't emulate the floating bus, and returns always 255 when reading a non-existent port. Although the complete floating bus can be complex to emulate, "Escape..." (and other games) only needs to detect a non-255 value when the paper is being painted, and 255 when the border is being painted.
I tried to play "Escape from M.O.N.J.A.S.", but the game hangs at the very beginning, when it should show the main menu. I suspect that the problem is that it doesn't emulate the floating bus, and returns always 255 when reading a non-existent port. Although the complete floating bus can be complex to emulate, "Escape..." (and other games) only needs to detect a non-255 value when the paper is being painted, and 255 when the border is being painted.