Konami 4bpp sprite tile format

konami4bpp.txt

Konami 4bpp sprite tile format

16-bit graphics ROMs go in pairs
One 32-bit word describes a row of eight 4bpp pixels
Each byte is a bitplane

ROM      UUUUUUUUUUUUUUUULLLLLLLLLLLLLLLL
Bit      3322222222221111111111
         10987654321098765432109876543210
Pixel    01234567012345670123456701234567 (0=left)
Plane    33333333222222221111111100000000

Subtiles are 8x8 pixels (32 bytes)
The minimum addressable tile is 16x16 pixels, rendered as 4 subtiles arranged like this:
0 1
2 3

Sprites larger than 1 tile follow the same arrangement recursively
For example, a 32x32 pixel sprite (2x2 tiles) will be made of the following subtiles:
0 1  4 5
2 3  6 7

8 9  C D
A B  E F

Note that the hardware addresses those subtiles automatically given a single base tile
number for the sprite, by replacing the lower bits (no addition !)
For example, providing a base tile number of 0, 1, 2 or 3 for a
2x2 tile sprite like above will give identical results.