[Genesis Plus GX] Z80 RAM memory domain

[DevsArchive]

Genesis Plus GX does not swap bytes in Z80 RAM like it does with 68000 memory, and thus should not use MemoryDomainIntPtrSwap16Monitor. A friend was using the hex editor to poke at bytes in Z80 RAM for a game, and they were byteswapped.

[ghost]

Does this happen only in bizhawk or is it directly a genesis plus gx issue? Could it have been done on purpose at some point?

[nattthebear]

Probably a Bizhawk specific issue. I didn't validate the low level details of how the memory was mapped before making all of these domains. It should be easily fixable.

[DevsArchive]

It's specifically a BizHawk thing with the hex viewer. GPGX swaps 68000 memory bytes to optimize 16-bit accesses with hosts with little endian CPUs, but not Z80, since that's really only accessed in bytes. BizHawk takes into account the 68000 byteswapping, but it lumps Z80 memory into it when it's not supposed to. You can see the issue in the hex viewer if you set it to Z80 RAM and set it to display individual bytes: they'll be swapped.