INES Mapper 081
From NESdev Wiki
Jump to navigationJump to search
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 | No |
IRQ | No |
Audio | No |
iNES mappers | 081 |
This mapper is used on exactly one known game: Super Gun from NTDEC. Although the game's bankswitching code seems to suggest two separate data latches at $6000 and $8000-$FFFF (the latter with bus conflicts), the board actually latches the four lowest address bits, and ignores the write to $6000.
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
PRG/CHR Bank Select ($8000-$FFFF)
CPU address bit# 1111 1100 0000 0000 5432 1098 7654 3210 ---- ---- ---- ---- 1... .... .... PPCC |||| ||++------ Select 8 KB CHR ROM bank for PPU $0000-$1FFF ++-------- Select 16 KB PRG ROM bank for CPU $8000-$BFFF
Related
Discussion with PCB images and analysis as well as Kazzo dumping script