Originally Posted by byuu
Mapping something beyond its own accessible address isn't so bad. You have to approach it from a hardware address line perspective.

Let's say you have a 16 byte space, and you have 11 bytes worth of unique data. How would you make such a board for real? Keeping in mind that virtually every ROM is a power of two ...
8 + 2 + 1 = 11


byuu, I understood the ROM mapping when you first explained it two years ago (and MESS code works fine since then).

I'm now interested to understand in which way you handle WRITES to those areas, if there is cartRAM there (notice: RAM and not ROM wink )...
I think I'm doing it right (now, after 2-3 lines changed), but for some reason the code fails for some SuperFX mirroring... that's why I would still like to fully understand your code, which seems to cover those cases fine as well.