I have a unibios installed in the MV-1A I use in my cab. I have only played it in MVS setting. Holding A, B, C and Start enters to menu and also acts as a pause function. I have ver 2.3 and the screen blacks out to save the monitor, not sure if earlier revisions do the same thing. Congrats on scoring that cab from Shpoo, nice to see it's found a new home and that it remains in possession of someone on this forum.