NES 2.0 Mapper 281

NES 2.0 Mapper 281 is used for the 1997 Super HIK 4-in-1 multicart (JY-052) by J.Y. Company, which has 512 KiB each of PRG-ROM and CHR-ROM. A single bit in register $D003 selects both PRG and CHR outer banks, and extended nametable mirroring is selected via bit 3 of $D001. It is otherwise similar to Mapper 90.

Registers

$8000-$D000, $D002: As Mapper 90.

Nametable Mirroring Control Register ($D001)

Mask: $F003

7654 3210
---- ----
.... E.MM
     | ++- Select nametable mirroring if bit 3==0
     |     0: Vertical
     |     1: Horizontal
     |     2: One-screen page 0
     |     3: One-screen page 1
     +---- Select extended nametable mirroring
           0: Disabled, use $D001 bits 0-1
           1: Enabled, use $B000-$B007

Outer Bank Register ($D003)

Mask: $F003

7654 3210
---- ----
.... ...C
        +- Select 256 KiB outer PRG-ROM bank
        +- Select 256 KiB outer CHR-ROM bank

Notes

• PRG ($8000-$8FFF) and CHR ($9000-$AFFF) bank select register bits that select 256 KiB banks are masked off.