INES Mapper 197
iNES Mapper 197 denotes an MMC3 clone wired to support 512 KiB of CHR-ROM by increasing CHR banking granularity from 1/2 KiB to 2/4 KiB. All of its games are mapper hacks, usually by 卡聖 (Kǎshèng, NT-xxx cartridge codes), of games originally released on mappers 90 and 91. Submappers, assigned by Nestopia Plus!, denote three different wiring variants. PRG-ROM, nametable mirroring and IRQs function as in mapper 4.
Submapper 0
- Super Fighter III (PRG-ROM CRC32 0xC333F621), originally for Mapper 91.1.
Pin Connected to PPU A10 CHR-ROM A10 PPU A11 MMC3 PA10 GND MMC3 PA11 PPU A12 MMC3 PA12 MMC3 CHR A10 CHR-ROM A11 : : MMC3 CHR A17 CHR-ROM A18
So that the MMC3 sees the followings addresses:
Real PPU Addr MMC3 PPU Addr $0000 $0000 -> reg 0 AND $FE $0400 $0000 -> reg 0 AND $FE $0800 $0400 -> reg 0 OR $01 $0C00 $0400 -> reg 0 OR $01 $1000 $1000 -> reg 2 $1400 $1000 -> reg 2 $1800 $1400 -> reg 3 $1C00 $1400 -> reg 3
This results in the following CHR banks:
MMC3 reg# Meaning 0 4 KiB CHR-ROM bank at PPU $0000-$0FFF 1 unused 2 2 KiB CHR-ROM bank at PPU $1000-$17FF 3 2 KiB CHR-ROM bank at PPU $1800-$1FFF 4 unused 5 unused
Submapper 1
- Super Fighter III (PRG-ROM CRC32 0x2091BEB2), UNIF board name UNL-FC-28-5027, originally for Mapper 91.1.
Pin Connected to PPU A10 CHR-ROM A10 PPU A11 MMC3 PA10 Vcc MMC3 PA11 PPU A12 MMC3 PA12 MMC3 CHR A10 CHR-ROM A11 : : MMC3 CHR A17 CHR-ROM A18
So that the MMC3 sees the followings addresses:
Real PPU Addr MMC3 PPU Addr $0000 $0800 -> reg 1 AND $FE $0400 $0800 -> reg 1 AND $FE $0800 $0C00 -> reg 1 OR $01 $0C00 $0C00 -> reg 1 OR $01 $1000 $1800 -> reg 4 $1400 $1800 -> reg 4 $1800 $1C00 -> reg 5 $1C00 $1C00 -> reg 5
This results in the following CHR banks:
MMC3 reg# Meaning 0 unused 1 4 KiB CHR-ROM bank at PPU $0000-$0FFF 2 unused 3 unused 4 2 KiB CHR-ROM bank at PPU $1000-$17FF 5 2 KiB CHR-ROM bank at PPU $1800-$1FFF
Submapper 2
- Mortal Kombat III Special (NT-328/YY-030) (PRG-ROM CRC32 0x60815A7D), originally for Mapper 90.
Pin Connected to PPU A10 CHR-ROM A10 PPU A11 MMC3 PA10 and MMC3 PA11 PPU A12 MMC3 PA12 MMC3 CHR A10 CHR-ROM A11 : : MMC3 CHR A17 CHR-ROM A18
So that the MMC3 sees the followings addresses:
Real PPU Addr MMC3 PPU Addr $0000 $0000 -> reg 0 AND $FE $0400 $0000 -> reg 0 AND $FE $0800 $0C00 -> reg 1 OR $01 $0C00 $0C00 -> reg 1 OR $01 $1000 $1000 -> reg 2 $1400 $1000 -> reg 2 $1800 $1C00 -> reg 5 $1C00 $1C00 -> reg 5
This results in the following CHR banks:
MMC3 reg# Meaning 0 (AND $FE) 2 KiB CHR-ROM bank at PPU $0000-$07FF 1 (OR $01) 2 KiB CHR-ROM bank at PPU $0800-$0FFF 2 2 KiB CHR-ROM bank at PPU $1000-$17FF 3 unused 4 unused 5 2 KiB CHR-ROM bank at PPU $1800-$1FFF
Submapper 3
- 1995 Super 2-in-1 (2B20)
Like Submapper 0, but with an additional outer bank register at $6000-$7FFF:
Mask: $E000
D~7654 3210
---------
.... S..P
| +- PRG A17 if S=1
+---- PRG A17 mode
0: PRG A17=MMC3 PRG A17 (256 KiB)
1: PRG A17=P (128 KiB)
As the outer bank register uses the MMC3 clone's WRAM interface, writes only have an effect if WRAM is enabled and not write-protected via $A001.
