INES Mapper 191

iNES Mapper 191 denotes the circuit board used for Xiangfeng Cartoon's Chinese translation of Technos' すごろ Quest: Diceの戦士たち, entitled 赌神 (Dǔshén). Having increased the PRG-ROM and CHR-ROM size from 128+128 KiB to 256+256 KiB without fully using it for the translation, Xiangfen Cartoon filled up the remaining space with three bonus games, making the cartridge a 4-in-1 multicart, with the main feature game using a dual "CHR-ROM plus 2 KiB of CHR-RAM" configuration similar to TQROM.

Because the multicart functionality was only discovered recently, and because the common dump trims CHR-ROM to 128 KiB, removing the CHR pattern data of the three bonus games, Submapper 0 disables the outer bank register and always keeps the CHR-ROM/CHR-RAM switch enabled, while Submapper 1 enables the outer bank register and allows proper emulation. For iNES-headered files without submapper information, use submapper 1 when the CHR-ROM size is 256 KiB and submapper 0 when the CHR-ROM size is 128 KiB. Running the full 256+256 KiB ROM file as submapper 0 skips the menu and boots directly into the main feature game.

Outer Bank Register ($90AA, write)

D~[.... ..GG] A~[1001 .... 1010 1010] (Address AND $F0FF)=$90AA
          ++- PRG A15..A14 when CPU A14=1

Power-on value: 0

The outer bank register defines the behavior of a PAL/GAL that affects two aspects:

• PRG A15..A14 of the fixed banks, so in the 256 KiB PRG-ROM, the fixed 8 kiB banks are bank#:
  • Value 0: $18 and $19
  • Value 1: $1A and $1B
  • Value 2: $1C and $1D
  • Value 3: $1E and $1F
• CHR banking:
  • Values 0,1,2: CHR-ROM A17=1, CHR-RAM disabled
  • Value 3: CHR-ROM A17=0, MMC3's CHR A17 output selects 128 KiB CHR-ROM (0) or 2 KiB CHR-RAM (1)

Because the power-on value is 0, the reset vector for the 4-in-1 menu is at PRG-ROM offset $33FFC.