INES Mapper 183
INES Mapper 183 was supposedly assigned to represent the pirate variant of Gimmick! known as Shui Guan Pipe. It uses a VRC4 clone in the VRC4e configuration (VRC4 A0=CPU A2, VRC4 A1=CPU A3), but additional circuits on the board adds an ability for mapping 8 KiB PRG-ROM bank at $6000-$7FFF.
A~[011. .... .... PPPP] $6000-$7FFF
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++++- Set 8 KiB PRG-ROM bank at $6000-$7FFF (only banks 0-15 can be swapped)
Note that address bits are used for specifying bank number, not data bus (writing to $6002 would mean bank 2, $6004 = bank 4 $600A = bank 10, so on).
- Early implementions of Mapper 183 has a register at $A000 that switches 8 KiB PRG bank at $C000-$DFFF with the registers were masked with $F80C, but this was not the case for actual cartridge.
- Due to this, Gimmick VRC4 Hack is previously thought to not be Mapper 183.