INES Mapper 147

From Nesdev wiki
Jump to: navigation, search

INES Mapper 147 is used to denote the Sachen 3018 board, used by one game: Chinese Kungfu: 少林武者 (TC-011) and its Western localization Challenge of the Dragon (not to be confused with the Color Dreams game of the same name). The original 60-pin Chinese version has 128 KiB of PRG-ROM and 128 KiB of CHR-ROM, while the 72-pin Western localization only has 64 KiB of PRG-ROM and 128 KiB of CHR-ROM.

Banks

  • CPU $8000-$FFFF: 32 KiB switchable PRG ROM bank
  • PPU $0000-$1FFF: 8 KiB switchable CHR ROM bank

Registers (60-pin release)

The original 60-pin release uses a custom IC (marked "JV001") serving as a latch, adder and inverter. There are five registers: Input (6 bits), Output (6 bits), Register (6 bits), Mode (1 bit) and Invert (1 bit).

Mask: $E103
Read $4100-$4103: [RRRR RR..]: Read Register (with its bits 0-5), connected to the CPU data bus bits 2-7. Register bits 4-5 (CPU bits 6-7) are inverted if Invert==1. CPU bits 0-1 are open bus.
Write $4100: When Mode==0: Bits 0-5 of Register := Input, bits 0-3 being inverted if Invert==1.
             When Mode==1: Bits 0-3 of Register incremented by one, bits 4-5 unaffected.
Write $4101: Invert := Written value bit 2.
Write $4102: Input := Written value bits 2-7.
Write $4103: Mode := Written value bit 2.
Write $8000-$FFFF: Output := Register; written value is ignored.

The six Output bits have the following functions:

Written CPU bit:       76543210
Internal Register bit: 543210..
                       --------
                       ||||||
                       +----+-- Select 32 KiB PRG-ROM bank at CPU $8000-$FFFF (PRG A15-A16)
                        ++++--- Select 8 KiB CHR-ROM bank at PPU $0000-$1FFF (CHR A13-A16)

The two PRG-ROM bits are split up in this way due to board topology: the lower bit goes directly to the A15 pin of the two 64 KiB PRG-ROM chips, while the higher bit selects which 64 KiB PRG-ROM chip is enabled.

Registers (72-pin release)

The 72-pin release of the game has only 64 KiB instead of 128 KiB of PRG-ROM, and uses a simple data latch instead of the JV001 ASIC, with the data bits having compatible functions as the original value written to $4102 on the JV001 IC:

 Mask: $4103
 Bus conflicts in the mirror at $C102-$FFFE
 $4102: [PCCC CP..] - Select 32 KiB PRG bank and 8 KiB CHR bank

Notes

  • Despite the hardware differences between the 60- and 72-pin versions of the game, both a more complex emulation of the JV001 chip as well as a simple emulation of the data latch will work with both versions' ROM images, as the 60-pin version neither uses the adder or inverter functionalities of the JV001 chip nor checks the result available from reading $4100, and the 72-pin version retains the complete $4101/$4102/$4103 write sequence that would be necessary to operate the JV001 IC.
  • The GoodNES 3.23b ROM image of Chinese Kungfu: 少林武者 is defective despite being tagged with [!]: the wrong CHR banks are selected during attract mode and in the second area of gameplay. A good redump is available.

See also