The ability to load cartridge images from files is really cool, I assume it works for ROM carts only? What if you have a GROM only cart in the physical slot, could you still load a ROM cart from the SDD99? Do you also allow RAM mapping into the >6000 region using the SAMS mapping registers?
I'm glad you ask this , since GROM should be possible. I already have some code, but I also need at least the GS line, which is currently not connected. I'll try soldering a small wire and then we can see.
Regarding the mapping, no, I don't. That's because the read request at >6/7xxx is always handled by the cart handler, and not by the memory handler. It would be quite a hassle to change this, and I'm not seeing a real benefit here either.