INES Mapper 243

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iNES Mapper 243 denotes the Sachen SA-020A circuit board. Using an eight-register ASIC with a fake "74LS374N" marking, it supports up to 128 KiB PRG-ROM, and 128 KiB of CHR-ROM. It is used for only one game, 美女拳 - Honey Peach (SA-006).


  • CPU $8000-$FFFF: switchable 32 KiB PRG-ROM bank
  • PPU $0000-$1FFF: switchable 8 KiB CHR-ROM bank
  • Nametable mirroring: switchable H/V/Vertically-flipped L/One-screen


Register Index ($4100, write)

Mask: $C101

D~7654 3210
  .... .RRR
        +++- Select register number (Rx)

Register Data ($4101, read/write)

Mask: $C101

D~7654 3210
  .... .RRR
        +++- Register data

D~7654 3210
  .... ...A  R2: CHR A13
  .... ...B  R4: CHR A14
  .... ..PP  R5: PRG A16..A15
  .... ..DC  R6: CHR A16..A15
  ...  .MM.  R7: Nametable mirroring
              0: S0-S0-S0-S1 (lower right unique, or vertically-flipped L)
              1: Horizontal
              2: Vertical
              3: Single-screen, page 1

Registers 0, 1, and 3 have no external effect. All three bits in all eight registers are fully implemented and can be read from and written to.


The SA-150 PCB, denoted by INES Mapper 150, connects the same ASIC differently, changing the meaning of the CHR-bank-related register bits.

See also