Drag wrote:
Unfortunately, most of the GUI is in the firmware, and you'd need to reflash it if you wanted to change anything (even the font!). Thank goodness the mappers are stored on the card instead, since I think that's a little more important.
This is not entirely true, a lot of the GUI code is on the CF and is loaded as needed at $400-7FF as modules. The firmware (at $8000-FFFF) contains some often used routines like stuff for reading from CF etc. As far as I can remember it also uses CHR-RAM (at least it would make little sense to have a separate CHR-ROM chip on the cart for the firmware...) so it's definitely possible to write a module to load a different font.
It would, theoretically, be possible to replace the entire GUI just by modifying the files on the CF as well. The firmware always starts by loading a certain module from the CF card, so replace that with a module that loads a new FPGA configuration and the PRG-ROM (really RAM) from the CF (similar to how games are loaded), and you have got a replacement menu. However nothing about this stuff is documented, and personally I don't feel it's worth the trouble. You would pretty much have to rewrite everything.