Different system cards for Rondo of Blood easter egg

[elmisterache7]

Hi.
I recently discovered that if you load Rondo of blood with a system card other than the 3.0, you get a little "mini game".
Obviously this applies to a real system.
If I want to replicate this with the MiSTer, my only guess is that I would have to put a system card 1 or 2 as a cd_bios.rom, right?

[AngelicLiver]

Yes you'd need to swap the system card for the "wrong" one. I'm travelling for work at the moment and can't get to my MiSTer setups but it might be possible to make an MGL file to do this without too much fuss?