I've tried to do some mapper development this weekend, making a mapper30 implementation. (based on Loopy's mapper sources)
But I seem to have fall into an unexpected pitfall: My mapper30 *only* works with TheFox's pc2nes software. When I put the .MAP file on the cartridge and try to load any ROMs from the powerpak OS, I just get a garbage screen.
Current state of the mapper30 implementation can be found here:
https://drive.google.com/open?id=1ifLP6yBpEE0EEzxZjsewQ1-kRehJg7FzAs mentioned, it works with the pc2nes tool, but does not support 4-screen/singlescreen mirroring with that tool, due to iNES byte 6 being ANDed with 1 when written to the mirroring configuration register. So there's already a bit of a difference between the pc2nes software/Powerpak OS. Though that difference doesn't really explain it not working at all.
Or it could just be my Verilog that is FUBAR. But would anyone know about any specific differences between pc2nes and the Powerpak OS NES ROM loading and configuration?
The pc2nes program has source to study,
but the Powerpak OS does not. And as I'm going on a long holiday from in 24 hours from now I won't have much ability to debug. It's one of those times where I've started a project on a tight deadline and wish I could turn the almost-working to actually-working, just to have it off my mind for the next few weeks. So any last-minute tips would be much appreciated...
EDIT: Just realised there ARE sources for the Powerpak. So at least it should make debugging this easier when I'm back...