INES Mapper 115

iNES Mapper 115 is used for an MMC3-clone-bearing board with a 256 KiB outer CHR-ROM bank register and an NROM-like PRG-ROM register that can override the MMC3 clone's PRG-ROM bank. Used by games from 卡聖 (Kǎshèng):

• A.V. 究極麻將 II (A.V. Jiūjí Májiàng II, Kǎshèng re-release, originally released by 哥德 (Gouder) on INES Mapper 116)
• 包青天 (Bāo Qīngtiān, Justice Pao)
• 雷電 II - Thunderbolt Fighting Plane (Léidiàn II)
• 三國春秋: 四川省 (Sānguó Chūnqiū: Sìchuān Shěng)
• 幽☆遊☆白書 Final (Yū Yū Hakusho Final, both Chinese and English versions)

Registers

NROM Override Register ($6000)

Mask: Probably $E001

D~7654 3210
  ---------
  M.S. BBBb
  | |  ++++- Select 16 KiB PRG-ROM bank at CPU
  | |        $8000-$BFFF and $C000-$FFFF
  | +------- 0: Do not replace bit 0 (NROM-128)
  |          1: Replace bit 0 with CPU A14 (NROM-256)
  +--------- 0: Use PRG bank from MMC3; ignore $6000 bits 0-3/5
             1: Ignore PRG bank from MMC3; apply $6000 bits 0-3/5

Outer CHR-ROM Bank Register ($6001)

Mask: Probably $E001

D~7654 3210
  ---------
  .... ...+- Select 256 KiB CHR-ROM bank at PPU $0000-$1FFF

MMC3-compatible registers ($8000-$FFFF)

Mask: $E001, see MMC3.

Notes

• Unlike many similar mappers, the $600x registers are not connected to the MMC3 clone's WRAM interface and thus function regardless of whether WRAM is enabled or not.
• IRQ behavior resembles that of the MMC3C, i.e. a latch value of zero causes an IRQ on every scanline, on which the Chinese version of 幽☆遊☆白書 Final (Yuu Yuu Hakusho Final) depends.

Similar Mappers

• INES Mapper 114 has the same $6000 and $6001 registers, but additionally scrambles MMC3 register addresses and indices. Also, Mapper 114's IRQ behavior resembles that of the MMC3A, i.e. a latch value of zero disables IRQ.
• INES Mapper 248 is a duplicate of Mapper 115.