A map is a dynamically-sized arrangement of blocks. Each map may use up to 5 pre-defined tilesets, and defines its own blocks.

Components

Tiles

A tile is an 8x8 arrangement of pixels. Tile pixel data is stored in VRAM. The first tileset of a map starts at tile index 0x100 in VRAM, and since each tileset is 128 tiles, that means tileset #2 is at 0x180, tileset #3 is at 0x200, etc. We will call this the VDP Tile Index.

Tileset

A tileset is a set of 128 tiles.

Block

A block is 3x3 arrangement of tiles, defined per map. Each block is 18 bytes (9 tiles * 2 bytes per tile), and each 2 bytes represents one VDP Tile Index. In addition to the VDP Tile Indexes, each tile index contains 2 bits -- one for horizontally flipped (0x0800), and one for vertically flipped (0x0400).

ROM

Byte 1      palette number to use
Byte 2      tileset number for ???
Byte 3      tileset number for above sprites layer ???
Byte 4      tileset number for background layer ???
Byte 5      tileset number for obstructed empty space ???
Byte 6      tileset numbre for decoration on background layer ???
Byte 7...   10 addresses

Address 1   compressed block definitions (tile indexes from 5 used tilesets)
Address 2   compressed map layout (block indexes from section 1)
Address 3   map properties (size, music, etc) -- different "rooms" go in order

    Byte 00-01  X1 bound
    Byte 02-03  Y1 bound
    Byte 04-05  X2 bound
    Byte 06-07  Y2 bound
    Byte 08-09  X1 bound of layer 2
    Byte 0a-0b  Y1 bound of layer 2
    ...
    Byte 10-11  X parallax of layer 2
    Byte 12-13  Y parallax of layer 2
    Byte 14-15  X parallax
    Byte 16-17  Y parallax
    Byte 18     X autoscroll of layer 2
    Byte 19     Y autoscroll of layer 2
    Byte 1a     X autoscroll
    Byte 1b     Y autoscroll
    Byte 1c
    Byte 1d     music to play
    
Address 4   flags and block changes if those flags are true

    Byte 00-01  flag
    Byte 02     top-left X coord of source
    Byte 03     top-left Y coord of source
    Byte 04     width to copy
    Byte 05     height to copy
    Byte 06     top-left X coord of dest
    Byte 07     top-left Y coord of dest

Address 5   block changes triggered by stepping (same as address 6)
Address 6   hiding roof somehow (x trig coord, y trig coord, x copy coord, y copy coord, width, height, x dest, y dest) - copy tiles to hide roof?
Address 7   warp
Address 8   treasure list -- chests (4 bytes each (x, y, flag, item idx), terminated with FFFF)
Address 9   treasure list -- non-chests (4 bytes each (x, y, flag, item idx), terminated with FFFF)
Address 10  animated tiles data

RAM

• Map layout definition (block indexes) are loaded into RAM at 0xFF0000.
• Block definitions (VDP tile indexes) are loaded into RAM at 0xFF2000.