NES 2.0 Mapper 282

NES 2.0 Mapper 282 is used by at least three J.Y. multicarts:

• 1997 Super HIK 18-in-1 (JY-101)
• 1997 Super HIK 21-in-1 (JY-105)
• 1998 Super HIK 5-in-1 (JY-114)

Each of them have 1 MiB each of PRG-ROM and CHR-ROM. Register $D003 controls 256 KiB 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
---- ----
...M CPPC
   | |||+- Select 256 KiB outer CHR-ROM bank
   | |++-- Select 256/512 KiB outer PRG-ROM bank
   | +---- If bit 4==1: Select 512 KiB outer CHR-ROM bank
   +------ 0: Ignore bit 3
           1: Obey bit 3

Notes

• PRG ($8000-$8FFF) and CHR ($9000-$AFFF) bank select register bits that select 256/512 KiB banks are masked off.

Trivia

Some of the multicarts show different version of menu according to what $5000 is returned from the mapper (the value that is read is masked with $C0, so only bits 7 & 6 matters.):

1997 Super HIK 21-in-1 (JY-105)
 $00   -> 21 in 1
 $40   -> 350 in 1
 $80   -> 1200 in 1
 $C0   -> 7000000 in 1
 
1997 Super HIK 18-in-1 (JY-101)
 $00   -> 18 in 1
 $40   -> 900 in 1
 $80   -> 1600 in 1
 $C0   -> 6000000 in 1