INES Mapper 154: Difference between revisions
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m (Add comment about niggling doubt) |
m (i'm on crack, there's no way there can be bus conflicts when the n108 disables the prg on writes.) |
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[[Category:iNES Mappers]][[Category:MMC3-like mappers]] | [[Category:iNES Mappers]][[Category:MMC3-like mappers]] | ||
Looking at [http://bootgod.dyndns.org:7777/profile.php?id=3837 bootgod's db], it looks like the M bit | Looking at [http://bootgod.dyndns.org:7777/profile.php?id=3837 bootgod's db], it looks like the M bit might be present in both $8000 and $8001 registers, but I can't be certain from the pictures. | ||
but I can't be certain from the pictures. | |||
Here are Disch's original notes: | Here are Disch's original notes: |
Revision as of 01:19, 14 June 2012
Looking at bootgod's db, it looks like the M bit might be present in both $8000 and $8001 registers, but I can't be certain from the pictures.
Here are Disch's original notes: ======================== = Mapper 154 = ======================== Example Game: -------------------------- Devil Man Registers: --------------------------- Range,Mask: $8000-FFFF, $8001 $8000: [.M.. .AAA] M = Mirroring 0 = 1ScA 1 = 1ScB A = Address for use with $8001 $8001: [DDDD DDDD] Data port: R:0 -> CHR reg 0 R:1 -> CHR reg 1 R:2 -> CHR reg 2 R:3 -> CHR reg 3 R:4 -> CHR reg 4 R:5 -> CHR reg 5 R:6 -> PRG reg 0 (8k @ $8000) R:7 -> PRG reg 1 (8k @ $A000) CHR Setup: --------------------------- $0000 $0400 $0800 $0C00 $1000 $1400 $1800 $1C00 +---------------+---------------+-------+-------+-------+-------+ | <R:0> | <R:1> | R:2 | R:3 | R:4 | R:5 | +---------------+---------------+-------+-------+-------+-------+ R:0,R:1 select CHR from the first 64k block. R:2-R:5 select CHR from the second 64k block. Therefore, you must effectively AND the written values to R:0,R:1 with $3F, and OR the written values to R:2-R:5 with $40. PRG Setup: --------------------------- $8000 $A000 $C000 $E000 +-------+-------+-------+-------+ | R:6 | R:7 | { -2} | { -1} | +-------+-------+-------+-------+