Checked Accelebrid, it does:
82D280: JSR ($d284,X) ;X is -0xfffe (!)
8260D2: SBC $ffffff,X ;bsnes has a rts here
8260D6: SBC $ffffff,X
...
827FFE: SBC $30c2ff,X
wrong rom image mapping I suppose ... or open bus.
everything is possible, but I doubt it's a rom mapping fault. I double checked the mapping and it seems fine (same as bsnes I mean). I could have overlooked something, of course...
fwiw, if it calls bank1_r (as you mentioned in the shoutbox), then it's trying to access "banks" 0x00-0x20 or 0x80-0xa0 (the latter is covered by bank6_r, but for most cases this calls bank1_r). in both cases 0x7fff is either reserved or DSP1/2/3/4 (but this game does not have special chips, iirc)
EDIT: ok, Reserved memory should fall back to open bus (as in bsnes and as explained at
http://www.bannister.org/forums/ubbthreads.php?ubb=showflat&Number=52896#Post52896 ). it does not fix Accelebrid, but it should be an improvement to accuracy. hence, I'm going to commit this change soon
EDIT2: added to svn
