INES Mapper 103

iNES Mapper 103 describes a specific pirate port of the FDS version of Doki Doki Panic.

Banks

• CPU $6000-$7FFF: 8 KiB RAM, or 8 KiB controllable ROM bank.
• CPU $8000-$B7FF: 14 KiB ROM, starting at ROM offset 0x18000
• CPU $B800-$D7FF: 8 KiB RAM, or 8 KiB fixed ROM bank, starting at ROM offset 0x1B800
• CPU $D800-$FFFF: 10 KiB ROM, starting at ROM offset 0x1D800

Writes to regions where RAM can be mapped will always write to RAM, even if RAM isn't enabled for reading.

Registers

Registers are not cleared on reset, and state is unknown on power-up. No bus conflicts.

PRG bank ($8000-$8FFF)

Mask: $F000

7  bit  0
---- ----
.... PPPP
     ||||
     ++++-- select 8 KiB PRG bank at $6000

Mirroring control ($E000-$EFFF)

Mask: $F000

7  bit  0
---- ----
.... m...
     |
     +----- 0=V (PPU A10), 1=H (PPU A11)

RAM disable ($F000-$FFFF)

Mask: $F000

7  bit  0
---- ----
...d ....
   |
   +------- 0=RAM available at $6000-$7FFF and $B800-$D7FF
            1=ROM instead

Hardware

This hardware involves three 7400, two 7410, a 7432, a 7474, a 74138, a 74157, and a 74161.

See also

• Krzysiobal's reverse engineered documentation