NES 2.0 Mapper 409: Difference between revisions
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Rainwarrior (talk | contribs) (mention actual usage in A Winner Is You) |
Rainwarrior (talk | contribs) (→Address Latch ($C000-$CFFF, write): trying to clarify what this description means) |
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------------------- | ------------------- | ||
1... BBBB BBBB BBBB | 1... BBBB BBBB BBBB | ||
++++-++++-++++- PRG A25..A14 | ++++-++++-++++- Selects bank via PRG A25..A14 at CPU $8000-BFFF (CPU A14=0) | ||
=See also= | =See also= | ||
* https://forums.nesdev.org/viewtopic.php?t=15188 | * https://forums.nesdev.org/viewtopic.php?t=15188 | ||
* https://web.archive.org/web/20191024003230/nintendoage.com/forum/messageview.cfm?catid=34&threadid=160050 | * https://web.archive.org/web/20191024003230/nintendoage.com/forum/messageview.cfm?catid=34&threadid=160050 | ||
Revision as of 20:40, 17 January 2023
NES 2.0 Mapper 409 denotes the retroUSB DPCMcart circuit board, used for the homebrew music cartridge "A Winner is You" released by retroUSB.. It is basically an extremely oversized version of UNROM that latches twelve bits of the address, rather than the data, bus for selecting banks from a 64 MiB PRG address space.
Despite being called "DPCMcart", due to its fixed bank it cannot actually bank DPCM samples. Instead. in A Winner is You used the large ROM for PCM sample storage, played back with timed CPU code.
Banks
- CPU $8000-$BFFF: 16 KiB PRG bank, switchable
- CPU $C000-$FFFF: 16 KiB PRG bank, fixed to last bank
- PPU $0000-$1FFF. 8 KiB CHR RAM, unbanked
- Mirroring: Hard-wired
Registers
Address Latch ($C000-$CFFF, write)
Mask: unknown, probably $8000
A~FEDC BA98 7654 3210
-------------------
1... BBBB BBBB BBBB
++++-++++-++++- Selects bank via PRG A25..A14 at CPU $8000-BFFF (CPU A14=0)
