Enhanced ULA Control Register

Number	$43
Readable	Yes
Writable	Yes
Short Description	Enables or disables Enhanced ULA interpretation of attribute values and toggles active palette.

Bit	Function
7	1 to disable palette index write auto-increment
6-4	Select palette for reading or writing
3	Select Sprites palette (0 = first palette, 1 = second palette)
2	Select Layer 2 palette (0 = first palette, 1 = second palette)
1	Select ULA palette (0 = first palette, 1 = second palette)
0	Enable ULANext mode if 1. (0 after a reset)

Possible bits 6-4 for palette select (bit 6 selects first/second, 5-4 select type):

Bits 6-4	selects
%000	ULA first palette
%100	ULA second palette
%001	Layer 2 first palette
%101	Layer 2 second palette
%010	Sprites first palette
%110	Sprites second palette
%011	Tilemap first palette
%111	Tilemap second palette

Write will also reset the index of Enhanced ULA Palette Extension ($44), so the next write there will be considered as first byte of colour.