iNES Mapper 134 denotes an MMC3-clone-based multicart PCB referred to alternatively as T4A54A, WX-KB4K, or BS-5652.
Mask: $E003
D~7654 3210
---------
LDcp C...
|||| +---- CHR-ROM banking mode
|||| 0: MMC3 (inner banks from $8000.0-$8000.5)
|||| 1: CNROM (8 KiB inner bank from $6002)
|||+------ PRG A19
||+------- CHR A19
|+-------- CPU $8000-$FFFF mode
| 0: PRG-ROM
| 1: Read solder pad setting
+--------- $6xxx Register Lock (except $6002.0-1)
0: unlocked
1: locked, further writes ignored until reset
Mask: $E003
D~7654 3210
---------
NcCC npPP
|||| ||++- PRG A18..17
|||| |+--- Outer PRG Bank Size
|||| | 0: 256 KiB, PRG A17 from MMC3
|||| | 1: 128 KiB, PRG A17 from $6001 bit 0
|||| +---- PRG A14 mode in NROM mode ($6001 bit 7=1)
|||| 0: PRG A14=CPU A14 (NROM-256)
|||| 1: PRG A14=MMC3 PRG A14 (NROM-128)
||++------ CHR A18..17
|+-------- Outer CHR Bank Size
| 0: 256 KiB, CHR A17 from MMC3
| 1: 128 KiB, CHR A17 from $6001 bit 4
+--------- PRG-ROM banking mode
0: MMC3
1: NROM
In NROM mode, the MMC3 clone's CPU A13 and A14 inputs are held low, so that MMC3 register 6 applies to the entire CPU $8000-$FFFF range, with PRG A13 substituted by CPU A13 and PRG A14 subject to $6001.3.
Mask: $E003
Contains the 8 KiB CHR-ROM bank if $6000.3=1, masked to 128 or 256 KiB according to $6000.6. Bits 0-1 respond even if the "Lock" bit is set, while changes to bits 2-7 will be ignored if the "Lock" bit has been set.
Mask: $E003
Mask: $E001 See MMC3.
Categories: Mappers with scanline IRQs, INES Mappers, MMC3-like mappers, Multicart mappers