INES Mapper 132
INES Mapper 132 is used to denote three compatible boards used by games from TXC Corporation:
- TXC 01-22003-400 PCB: 72 pins with CIC stun circuit, TXC 05-00002-010 ASIC, max. 64 KiB PRG-ROM, max. 32 KiB CHR-ROM
- TXC 01-22111-100 PCB: 60 pins, TXC 05-00002-010 ASIC, max. 64 KiB PRG-ROM, max. 32 KiB CHR-ROM
- TXC 01-22270-000 PCB: 60 pins, TXC 05-00002-010 ASIC or 74LS161 latch, max. 64 KiB PRG-ROM, max. 32 KiB CHR-ROM
|棋王 (Qíwáng, Chinese Chess)||MGC-001||64 KiB||32 KiB|
|Creatom||MGC-003||64 KiB||32 KiB|
|小瑪琍 (Xiǎo Mǎlí)||MGC-005||16 KiB||8 KiB||TXC re-release, no bankswitching or copy-protection. Cartridge label titles it Bingo.|
|麻将方块 (Mahjong Block)||MGC-008||32 KiB||32 KiB||TXC re-release|
|Venice Beach Volley||MGC-010||32 KiB||32 KiB||TXC re-release|
|Rad Racket - Deluxe Tennis II||MGC-011||32 KiB||32 KiB||TXC re-release|
Its UNIF board name is UNL-22211.
- CPU $8000-$FFFF: 32 KiB switchable PRG ROM bank
- PPU $0000-$1FFF: 8 KiB switchable CHR ROM bank
Mapper 132 uses a custom IC (real number 05-00002-010, often with fake markings) serving as a latch, adder and inverter. There are six registers: "P", "R", and Output (three bits each); "S", inCrement, and and inVert (one bit each).
Mask: $E100 read $4100: [xxxx SRRR] |||| |||| |||| ++++- Copy internal registers 'RRR' and 'S' XOR 'V' to data bus. ++++------ open bus Mask: $E103 write $4100: If Increment is set, internal register 'RRR' <- 'RRR'+1 Otherwise, if Invert is clear, copy internal register 'PPP' to 'RRR' if Invert is set, copy '~PPP' to 'RRR' 'S' is not changed at all. write $4101: [.... ...V] - Invert Mode write $4102: [.... SPPP] - Copy data bus to internal registers 'S' and 'PPP'. 'S' can be read back immediately; 'PPP' must be copied using $4100 first. write $4103: [.... ...C] - Increment Mode Mask: $8000 write $8000: copy internal register 'RRR' to PRG A15, CHR A14, and CHR A13 banking pins, in order.
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.
TXC 01-22270-000 PCB with 74LS161 latch
Instead of the 05-00002-010 ASIC, the 01-22270-000 PCB variant can also use a simple 74LS161 latch, which would make the board function as MHROM.
- 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.
- The TXC re-release of 小瑪琍 (Xiǎo Mǎlí), with cartridge code MGC-005, uses the 01-22111-100 board as well, but since it does not use any bankswitching whatsoever, it can be emulated as mapper 0.
- 麻将方块 (Mahjong Block) (TXC re-release, headerless CRC32 0ACFC3CD) is commonly set to INES Mapper 173, but since it expects Output bit 1 to select CHR A14, it actually uses INES Mapper 132. Note that the original Super Mega release of the game uses INES Mapper 172.
- 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 for PRG-ROM banking and moves CHR-ROM banking to a separate data latch.