Tilemap Transparency Index Register

From SpecNext official Wiki
Jump to: navigation, search
Number $4C
Readable Yes
Writable Yes
Short Description Index into Tilemap palette (of "transparent" colour).
bits 7-4 = Reserved, must be 0
bits 3-0 = Set the index value (0xF after reset)

The pixel index (bottom 4 bits) from tile graphics is compared before the palette offset is applied to upper 4 bits, so there is always one index of the 0-15 working as "transparent" colour.