in the current version the user subroutine detects the bios version (MVS/AES) and bios country code ( (JAP/USA/EUR)
and acts accordingly to it (MVS mode with shared or independent credit counters, different P1/P2 START button
behavoir, AES mode with "virtual" credits). The routine now can handle two players (single or simultaneous game play).
Also, I have added user_request=0 to the code and now I can read the data from the bios soft dips, load default highscore
data and save new highscore data to the MVS backup RAM. Overall, I am pretty happy with it and just want to say again:
Thank you HPMAN
Here is a video of the actual status: