INES Mapper 132

INES Mapper 132 is used to denote the TXC 01-22270-000 and 01-22111-100 boards, used by a few games from TXC Corporation:

• 棋王 (Qíwáng, Chinese Chess) (MGC-001, 64 KiB PRG-ROM)
• Creatom (MGC-003, 64 KiB PRG-ROM)
• 麻将方块 (Mahjong Block) (TXC re-release) (MGC-008, 32 KiB PRG-ROM)
• Venice Beach Volley (TXC release, MGC-010, 32 KiB PRG-ROM)
• Rad Racket - Deluxe Tennis II (TXC release, MGC-011, 32 KiB PRG-ROM)

Its UNIF board name is UNL-22211.

Banks

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

Registers

Mapper 132 uses a custom IC (real number 05-00002-010, often with fake markings) serving as a latch, adder and inverter. There are five registers: Input (4 bits), Output (4 bits), Register (4 bits), Mode (1 bit) and Invert (1 bit).

Mask: $E103
Read $4100-$4103: [.... RRRR]: Read Register. Bit 3 is inverted if Invert==1. Bits 4-7 are open bus.
Write $4100: When Mode==0: Bits 0-3 of Register := Input, bits 0-2 being inverted if Invert==1.
             When Mode==1: Bits 0-2 of Register incremented by one, bit 3 unaffected.
Write $4101: Invert := Written value bit 0.
Write $4102: Input := Written value bits 0-3.
Write $4103: Mode := Written value bit 0.
Write $8000-$FFFF: Output := Register; written value is ignored.

In Mapper 132, Output is connected as follows:

 3210
 ----
 .|++- Select 8 KiB CHR-ROM bank at PPU $0000-$1FFF (CHR A13/A14)
  +-- Select 32 KiB PRG-ROM bank at CPU $8000-$FFFF (PRG A15)

Games will also check the lower three or four bits of $4100 for the correct value after several increment and inversion operations as a copy-protection measure.

Notes

• 戰國四川省 (Zhànguó Sìchuān Shěng, original version of AVE's Tiles of Fate) is set to Mapper 132 in GoodNES 3.23b. That ROM image is actually a mapper hack with the PRG-ROM code unmodified but the CHR-ROM banks rearranged to work as Mapper 132; the correct mapper is INES Mapper 173. That mapper hack only works on certain emulators' implementation of Mapper 132, not on the above implementation based on studying the circuit board.

Similar Mappers

• On games with only 32 KiB PRG-ROM, Mapper 132 is almost identical to INES Mapper 136 except in the value read from $4100 due to Mapper 136 having four (28-pin JV001 ASIC) versus Mapper 132 having three adder bits (24-pin 05-00002-010 ASIC).
• On games with only 32 KiB PRG-ROM, INES Mapper 173 is similar to Mapper 132 except that CHR A14 is taken from the inverse of the Invert bit rather than Output bit 1.
• INES Mapper 036 is somewhat similar, using the same 05-00002-010 ASIC. It utilizes CPU bits 4 and 5 instead of 2 (and 3, if an 128 KiB Mapper 132 game existed) for PRG-ROM banking and moves CHR-ROM banking to a separate data latch.

See also

PCB images