User talk:Zzo38/Submappers

There's a bunch here that seem unnecessary to me. For example:

• Mapper 1, all of these boards are disambiguated just with the PRG-RAM size register, so why allocate submappers?
  • That said, SEROM and SHROM are not describable using other details, so there's an argument for why they should.
• Mappers 2,3 submappers should probably also apply to 7 and 34
• Mapper 4 MMC3 vs MMC6 can also be disambiguated using the PRG-RAM size register
• I'm not clear why any of the VRC2x/VRC4x/VRC6x/VRC7x layouts need to be disambiguated.
  • That said, using submappers to disambiguate VRC2 from VRC4 is a great idea.
• Mappers 38,79: I think enshrining either behavior as official is a bad idea, especially since Nestopia's implementation is a superset of FCEUX's in both cases. (And FCEUX happens to be on crack with m79's register at $8000)

—Lidnariq 20:13, 10 September 2012 (MDT)

Thanks for your comments. OK, I have listed 7 and 34 under the 2 and 3 heading. For mapper 38 and 79 I have added a comment; hopefully someone who understands better will fix it. I don't know much about the differences of SEROM, SHROM, SOROM, SXROM, SUROM, but at least to me it would make sense that the same mapper/submapper number is used if and only if it makes sense that it is otherwise similar enough other than the PRG-RAM size! For VRC7a/VRC7b, I quote: "VRC7a uses $x010 for regs, and VRC7b uses $x008." I suppose it could be mirrored byt doesn't make sense from a hardware perspective (unless, perhaps, you use a OR gate on bit3 and bit4 of the address; which seems strange to me, though). As I have written above, the reason I think MMC3 and MMC6 different numbers, and I quote again: "It is also mapped a bit differently, and is enabled/disabled differently from MMC3." For the VRC4x, registers are mapped differently. Some of these reasons are in case you want to write a homebrew using these mappers with different ROM/RAM amounts (of course, the RAM amounts should always be zero if the mapper does not specify any registers to control it, and in some cases there are simple changes to the registers just using different number of bits so they shouldn't have a different number, but in some cases they really are different other than just the ROM/RAM amounts). At least this is my opinion. You can ask other people working on NES/Famicom to see if they know better; I don't know it that well, and as I wrote in the document, these are only suggestion (subject to change) and not official specifications in any way (this is why it is a subpage of my userpage instead of main namespace). --Zzo38 22:56, 10 September 2012 (MDT)