ULA Control Register

Number	TBRegisterNumber::$68
Readable	TBRegisterReadable::Yes
Writable	TBRegisterWritable::Yes
Short Description	ShortDesc::Disables ULA completely and controls its mixing with Tilemap layer.

Bit	Function
7	1 to disable ULA output
6	0 to select the ULA colour for blending in SLU modes 6 & 7 1 to select the ULA/tilemap mix for blending in SLU modes 6 & 7
5-1	Reserved, must be 0
0	1 to enable stencil mode when both the ULA and tilemap are enabled (if either are transparent the result is transparent otherwise the result is a logical AND of both colours)

Bit 0 can be set to choose stencil mode for the combined output of the ULA and tilemap.

Bit 6 determines what colour is used in SLU modes 6 & 7 where the ULA is combined with Layer 2 to generate highlighting effects.

Default value is 0.