As you can see in the image below, Earthworm Jim 2 loads and runs in my emulator, but the background tiles look messed up. The sprites, the music and sound effects, and the game play seem to be working aside from the scrambled background.
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:
Since FCEUX doesn't have the equivalent code, I assume it is not completely necessary.
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.
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:
int MAPINT Read (int Bank, int Addr)
{
if (Addr & 0x800)
return (*EMU->OpenBus & 0xFE) | (((~Addr >> 8) | Addr) & 1);
else return -1;
}
{
if (Addr & 0x800)
return (*EMU->OpenBus & 0xFE) | (((~Addr >> 8) | Addr) & 1);
else return -1;
}
Since FCEUX doesn't have the equivalent code, I assume it is not completely necessary.
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.