INES Mapper 180

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 INES Mapper 002 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.

Mapper 97 adds mapper-selectable 1sc/H/V mirroring (and changes the fixed 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: Yes

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
      |||
      +++-- Select 16 KB PRG ROM bank for CPU $C000-$FFFF

See also

• UxROM
• Programming UNROM
• NES mapper list by Dish [1]