NES 2.0 Mapper 519: Difference between revisions
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(combine the two latches; they're updated at the same moment) |
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[[Category:Multicart mappers]]NES 2.0 Mapper 519 is used for Chinese-language multicarts | [[Category:Multicart mappers]]NES 2.0 Mapper 519 is used for Chinese-language multicarts designated by the UNIF board name '''UNL-EH8813A'''. It latches both the CPU address and data buses. | ||
A~[1... .... MDPP PPPP] D~[CCCC CCCC] | A~[1... .... MDPP PPPP] D~[CCCC CCCC] | ||
Revision as of 20:53, 13 March 2018
NES 2.0 Mapper 519 is used for Chinese-language multicarts designated by the UNIF board name UNL-EH8813A. It latches both the CPU address and data buses.
A~[1... .... MDPP PPPP] D~[CCCC CCCC]
|||| |||| ++++-++++-- Select 8 KiB CHR-ROM bank at PPU $0000-$1FFF
||++-++++---------------- Select 16 KiB PRG-ROM bank at CPU $8000-$BFFF/$C000-$FFFF
|+----------------------- Read DIP switch mode
| 0: Disabled, reads from $8000-$FFFF normal
| 1: Enabled, when reading from $8000-$FFFF:
| Bitwise AND address with $FFF0 and OR with the DIP switch setting ($0-$F)
+------------------------ PRG-ROM banking mode
0: NROM-128 (16 KiB, $8000-$BFFF mirrored at $C000-$FFFF)
1: NROM-256 (32 KiB, bit 0 ignored)
All known ROM images always use Vertical mirroring, so it's not known whether mirroring is hardwired, or whether horizontal mirroring could be set using a so far unknown bit.
iNES Mapper 227 appears to also have the same "DIP switch" that can override LSBs of address so that the multicart can detect which variant it's pretending to be.
