NES 2.0 Mapper 533

NES 2.0 Mapper 533 is used for the Sachen 3014 board, used for the game 動動腦 II: 國中英文(一) (Dòngdòngnǎo II: Guózhōng Yīngwén (I), also known as Middle School English II, SA-003). It’s a CNROM-like board with the added ability to read back the latch content for protection purposes.

Banks

CPU $8000-$FFFF: Fixed 32 KiB PRG-ROM bank
PPU $0000-$1FFF: Switchable 8 KiB CHR-ROM bank
Mirroring: hard-wired

Registers

CHR Bank Select and Latch Write ($8000-$FFFF, write)

Mask: $8000

D~7654 3210
  ---------
  LLLl ....
  ++++------ Set latched value that can be read back at $E000-$EFFF
     +------ Select 8 KiB CHR-ROM bank at PPU $0000-$1FFF

Latch Read ($E000-$EFFF, Read)

Mask: $F000

D~7654 3210
  ---------
  .... LLLL
  |||| ++++- Latched value previously written to D4-D7 of $8000-$FFFF
  ++++------ value from ROM

Notes

The board is subject to bus conflicts when writing or reading. The software reads the latch ten times, assuming that after enough tries the driver will overpower the ROM.