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. It uses the J.Y. Company ASIC. A single bit in register $D003 selects both PRG and CHR outer banks.
Outer Bank Register ($D003)
7654 3210 ---- ---- .... ...C +- Select 256 KiB outer PRG-ROM bank +- Select 256 KiB outer CHR-ROM bank
PRG ($8000-$8FFF) and CHR ($9000-$AFFF) bank select register bits that select 256 KiB banks are masked off.
For a description of all other registers, see J.Y. Company ASIC.