The Submapper page states:
Can we allocate submapper 4 to mapper 4 for that? There already is a test ROM for that in the form of Blargg's mmc3_test, single rom "6-MMC3_alt.nes".
Quote:
MMC3A: IRQ is asserted on A12 rise, and loading the latch with 0 disables IRQ. Some chips labeled MMC3B also have this "old style" behavior. No games are known to rely on this behavior.
I know one: The Mapper 4 version of SuperGame's Aladdin, headerless CRC32 0x97B6CB19, named "Aladdin (SuperGame) (Mapper 4) [!]" in GoodNes 3.23b. The game writes 0 to $C000 but also to $E001. MMC3A behavior runs the game normally, MMC3C behavior makes it freeze after the title screen.Can we allocate submapper 4 to mapper 4 for that? There already is a test ROM for that in the form of Blargg's mmc3_test, single rom "6-MMC3_alt.nes".