07-18-2017, 07:16 PM
Hi, 
I've been adding BIOS support to BizHawk's port of Gambatte, and a user pointed out that GBA enhanced GBC games no longer work after doing so. As is known, register B is supposed to be 1 instead of 0 when booting from a GBA. Presumably the GBA contains a modified GBC Boot Rom for doing this. I looked over the GBC Boot Rom code and didn't see a trivial change that would make B=1 instead of zero after processing, so the Boot Rom in the GBA must be more like a different version.
So, can this version be dumped? Has it been already (and maybe I just can't find it?) Or is something else altogether happening?
Thanks for any insights, as this seems like a loose end to me that could use some clarification.
I've been adding BIOS support to BizHawk's port of Gambatte, and a user pointed out that GBA enhanced GBC games no longer work after doing so. As is known, register B is supposed to be 1 instead of 0 when booting from a GBA. Presumably the GBA contains a modified GBC Boot Rom for doing this. I looked over the GBC Boot Rom code and didn't see a trivial change that would make B=1 instead of zero after processing, so the Boot Rom in the GBA must be more like a different version.
So, can this version be dumped? Has it been already (and maybe I just can't find it?) Or is something else altogether happening?
Thanks for any insights, as this seems like a loose end to me that could use some clarification.