Dragon Warrior IV:ROM map

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Bank 08: (20000)

  • $8229 = Table with three possible base addresses for graphics tile data
    • Value 0x8000 (used with ROM bank 0C)
    • Value 0x7F01 (used with ROM bank 0D)
    • Value 0x9E14 (used with ROM bank 0D)
  • Memory around $8B9B (find this): Tile Numbers (TODO)
  • Tile Numbers:
    • Byte 0: yyyAAXXX
    • Byte 1: xxxxxxxx
      • yyy = Smoothing flags for front-facing tiles
      • AA = Attribute data (which Color palette to use)
      • XXXxxxxxxxx Tile number (Used as index into table $A80D)
  • $A80D = Table of tiles, three bytes per entry
    • Byte 0: Low byte of physical tile number
    • Byte 1: AAAABBCC
      • AAAA = ??? Flags for which VRAM tiles are unique or duplicated
      • BB = Which graphics page to read the tile graphics from
      • CC = High two bits of physical tile number
    • Byte 2: Tile Behavior (empty space, walls, water, stairs, etc...) See: Tile Behavior

Multiply Physical Tile Number by 16, add Base Address from table $8229 depending on graphic page value. ($8000, $7F01, or $9E14), choose either Rom Bank 0C or 0D. That gives the source address of the tile graphics.

Bank 0C: (30000)

  • $8000: Map Tile Graphics. Used when the game wants the tile graphics from page 0

Bank 0D: (34000)

  • $8001: Map Tile graphics. Used when the game wants tile graphics from page 1
  • $9F14: Map Tile graphics. Used when the game wants tile graphics from page 2
  • $B304: Character sprite graphics
  • $BE44: Empty space
  • $BFD4: End of empty space, some other code or data

Bank 0E: (38000)

  • $8097: Character sprite graphics
  • $BAD7: end of character sprite graphics, some other code or data

Bank 17: (5C000)

Maps 0x00-0x48 are defined. See Map List

There are two variables used to look up map numbers: Main Map Number ($63), and Submap Number ($64). Submaps include upstairs areas or different floors of a dungeon.

  • $B08D-$B11F: Pointer Table for Map Information. Points to a 3-byte Map Information Data entry. Add 3 * Submap Number to the address to select a Submap instead.
  • $B121-$B490+: Map Information data. There are FF byte separators.
    • Byte 0: Tileset Number
    • Byte 1,2: Map Data Address (low byte then high byte)