NES 2.0 Mapper 533: Difference between revisions
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(a few more words about bus conflicts) |
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--------- | --------- | ||
.... LLLL | .... LLLL | ||
|||| ++++- Latched value previously written to D4-D7 of $8000-$FFFF | |||
++++------ value from ROM | |||
=Notes= | =Notes= | ||
* The board is subject to [[bus | * The board is subject to [[bus conflict]]s when writing or reading. The software reads the latch ten times, assuming that after enough tries the driver will overpower the ROM. | ||
Revision as of 01:52, 30 September 2018
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.
