Documentation

[EtchedPixels]

Sticking them here for anyone who needs them:

The documentation example for mode setting writes the other bytes to the command not data which seems wrong.

The default base for the sprites and tile bitmap is set automatically on the mode set, allowing for the expansion options. Both are set the same.

The colour is not documented. As far as I can tell it's

RRGGBBXT where 'T' is set for transparency on sprites

Also worth noting the halt line is only needed on mode changes, clear screen on bitmap mode or if you try and use the halt until vblank feature. Thus on non Z80 setups or if you don't have halt handy a delay for those works fine.

Doubling the tilemap width/height does not change the number displayed (alas no 80 column mode) but allows you to scroll around a bigger map without having to reload tilemap data

There are more than 256 possible tiles. This is usable by moving the base up and down but the base affects the actual rendered display so it's mostly useful if you put the sprites at a different base to the background tiles