NES 2.0 Mapper 409: Difference between revisions
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'''NES 2.0 Mapper 409''' denotes the '''retroUSB DPCMcart''' circuit board, used for the [https://sergioelisondo.bandcamp.com/album/a-winner-is-you homebrew music cartridge "A Winner is You"] released by [https://retrousb.com/product_info.php?cPath=36&products_id=143 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. | '''NES 2.0 Mapper 409''' denotes the '''retroUSB DPCMcart''' circuit board, used for the [https://sergioelisondo.bandcamp.com/album/a-winner-is-you homebrew music cartridge "A Winner is You"] released by [https://retrousb.com/product_info.php?cPath=36&products_id=143 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", | Despite being called "DPCMcart", it cannot actually bank DPCM samples because of its fixed bank. Instead, ''A Winner is You'' uses the large ROM for PCM sample storage, played back with timed CPU code. | ||
=Banks= | =Banks= | ||
Revision as of 20:42, 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", it cannot actually bank DPCM samples because of its fixed bank. Instead, A Winner is You uses 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)
