FCEUmm; How to switch to Side B of a FDS game?

RetroArch Windows devices
#1

Pretty much that, how do I do it? I’m trying to play Nazo no Murasamejou but I cannot switch to Side B. I’ve tried binding the “Disk Eject” and “Disk Next” keys that are on the input section of retroarch but they do nothing.

Thanks in advance.

#2

This hasn’t been implemented yet. https://github.com/libretro/libretro-fceumm/issues/2

#3

Damn. Thanks a lot.