INES Mapper 180: Difference between revisions
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(According to bootgod's db, it's an actual UNROM board) |
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[[INES Mapper 180]] is used to represent a | [[INES Mapper 180]] is used to represent a reconfiguration of the [[UxROM|UNROM]] board used only for the game ''Crazy Climber''. It is similar in principle to the more common UxROM configuration but uses AND logic ([[7408|74HC08]]) instead of OR logic ([[7432|74HC32]]), producing a fixed first bank at $8000 rather than a fixed last bank at $C000. | ||
Because [[APU DMC]] is usually restricted to $C000-$FFFF, this behavior might be useful for games with a lot of recorded speech. | Because [[APU DMC]] is usually restricted to $C000-$FFFF, this behavior might be useful for games with a lot of recorded speech. | ||
Revision as of 15:35, 22 December 2010
INES Mapper 180 is used to represent a reconfiguration of the UNROM board used only for the game Crazy Climber. It is similar in principle to the more common UxROM configuration but uses AND logic (74HC08) instead of OR logic (74HC32), producing a fixed first bank at $8000 rather than a fixed last bank at $C000.
Because APU DMC is usually restricted to $C000-$FFFF, this behavior might be useful for games with a lot of recorded speech. But like BNROM and AxROM, this configuration requires the 6502's vectors to sit in the last few bytes of each bank.
Overview
- PRG ROM size: 128 KB
- PRG ROM bank size: 16 KB
- PRG RAM: None
- CHR capacity: 8 KB RAM
- CHR bank size: Not bankswitched
- Nametable mirroring: Solder pads select vertical or horizontal mirroring
- Subject to bus conflicts: ?
Banks
- CPU $8000-$BFFF: 16 KB PRG ROM bank, fixed to the first bank
- CPU $C000-$FFFF: 16 KB switchable PRG ROM bank
Registers
Bank select ($8000-$FFFF)
7 bit 0
---- ----
xxxx xPPP
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+++-- Select 16 KB PRG ROM bank for CPU $C000-$FFFF
