all emulators I know of only put 0x00 or 0xFF in the remaining bits, if this would have given problems with games, it would have been known by now ... on the opposite, how can you be sure than simulating mirroring for all games would not lead to problems with some badly programmed ones that would expect 0 from unmapped address ?eteream wrote:Years ago, when I made my emulator these things were taken into account in the very firsts steps, I'm surprised...
some roms are mirrored, some others are not, that's simple as thatAnd what else a cart designer can do?
Maybe I misunderstood it, but for example Sonic 1 is mirrored since pins A19-A23 (of cart pinout) are connected to nowhere. Well, there is no assurance at all, but most of 512k roms (without save feature) will go in the same way.
and as said above and by others, no games rely on this so a cart designer should not bother with this and do as emulators are doing.[/quote]