Serious emulation problem with Monster Race (GB)?

[Krys3000]

Hey, I have one of those GBA Movie Player! Good times playing NES on my DS Fat.

[Wack0]

I finally took a look at the "bad dump", turns out it's not really a "bad dump", someone modified the ROM.

Entry point jumps to 0:00e0, which is just nops in the good dump, but this space was used to add the following code:


ld a,0
ld [$6000],a
ld a,$30
ld [$6000],a
jp $0150


This code makes no sense, the header says it uses MBC1, where $6000 is a 1-bit wide register that flips between two different banking modes. Maybe this is for flashcart compatibility?

In addition, a ld a,1 got patched to ld a,0 at 00:024C, and again at 01:488E.

Finally, the header checksum got patched.

[Parzival]

Well then... we have our answer.