INES Mapper 081

N715021

Company	NTDEC
Complexity	Discrete logic
Boards	N715021
PRG ROM capacity	64K
PRG ROM window	16K + 16K fixed
PRG RAM capacity	None
CHR capacity	32K
CHR window	8K
Nametable mirroring	Fixed H or V, controlled by solder pads
Bus conflicts	Yes
IRQ	No
Audio	No
iNES mappers	081

This mapper is used on exactly one known game: Super Gun from NTDEC (cartridge code CN-21).

Banks

• CPU $8000-$BFFF: 16 KB switchable PRG ROM bank
• CPU $C000-$FFFF: 16 KB PRG ROM bank, fixed to the last bank
• PPU $0000-$1FFF: 8 KB switchable CHR ROM bank

Registers

CHR Bank Select ($6000-$7FFF)

7  bit  0
---- ----
..CC ....
  ||
  ++------ Select 8 KB CHR ROM bank for PPU $0000-$1FFF

PRG Bank Select ($8000-$FFFF)

7  bit  0
---- ----
.... PP..
     ||
     ++--- Select 16 KB PRG ROM bank for CPU $8000-$BFFF