NES 2.0 Mapper 307

NES 2.0 Mapper 307 is used for Kaiser's ROM cartridge conversion of the Japanese Famicom Disk System version of Metroid. Its UNIF board name is UNL-KS7037.

Banks

• CPU $6000-$6FFF: 4 KiB fixed PRG-RAM bank #0
• CPU $7000-$7FFF: 4 KiB fixed PRG-ROM bank #15
• CPU $8000-$9FFF: 8 KiB switchable PRG-ROM bank
• CPU $A000-$AFFF: 4 KiB fixed PRG-ROM bank #28
• CPU $B000-$BFFF: 4 KiB fixed PRG-RAM bank #1
• CPU $C000-$DFFF: 8 KiB switchable PRG-ROM bank
• CPU $E000-$FFFF: 8 KiB fixed PRG-ROM bank #15
• PPU $0000-$1FFF: 8 KiB unbanked CHR-RAM

Registers

$8000-$9FFE (even)

Select bank register number

$0-$1: No function
$2: Bit 0 selects 1 KiB CIRAM bank at PPU $2000-$23FF
$3: Bit 0 selects 1 KiB CIRAM bank at PPU $2800-$2BFF
$4: Bit 0 selects 1 KiB CIRAM bank at PPU $2400-$27FF
$5: Bit 0 selects 1 KiB CIRAM bank at PPU $2C00-$2FFF
$6: Select 8 KiB PRG-ROM bank at CPU $8000-$9FFF
$7: Select 8 KiB PRG-ROM bank at CPU $C000-$DFFF

$8001-$9FFF (odd)

Data for bank register selected by $8000-$9FFE (even).

Notes

• The conversion retains all writes to the FDS sound channel registers, so an emulator could provide the expansion sound channel even though the original Kaiser cartridge did not.
• Game progress cannot be saved; in fact, the save menu has been removed.
• The register layout indicates that an MMC3 or N118 clone is being used, connected in an unusual manner.
• Reverse-engineered schematic: forum