INES Mapper 197

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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