Since there is no wiki page on mapper UNL-H2288, I have been relying on the source code of other emulators for details. Earthworm Jim 2 executes perfectly in Nintendulator and FCEUX. Their mapper implementations are almost identical. However, Nintendulator includes this extra bit, likely related to the copy protection mechanism:
Code: Select all
int MAPINT Read (int Bank, int Addr)
{
if (Addr & 0x800)
return (*EMU->OpenBus & 0xFE) | (((~Addr >> 8) | Addr) & 1);
else return -1;
}
Could the scrambled background tiles in my emulator be copy protection related? I followed the register remapping per the aforementioned sources; so, I am looking for other possibilities. I appreciate any input on this issue. Thanks.