Difference between revisions of "ULA Control Register"

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(core 3.1.3 changes/refresh)
(core 3.1.4 changes/refresh)
 
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1 to select the ULA/tilemap mix for blending in SLU modes 6 & 7</del>
 
1 to select the ULA/tilemap mix for blending in SLU modes 6 & 7</del>
 
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| 4 || Reserved, must be 0
+
| 4 || since core3.1.4: Cancel entries in 8x5 matrix for extended keys
 
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| 3 || ULA+ enable (soft reset = 0)
 
| 3 || ULA+ enable (soft reset = 0)

Latest revision as of 00:08, 16 April 2020

Number $68
Readable Yes
Writable Yes
Short Description Disable ULA, controls ULA mixing/blending, enable ULA+
Bit Function
7 1 to disable ULA output (soft reset = 0)
6-5 since core3.1.1: Blending in SLU modes 6 & 7 (soft reset = 0)
= 00 for ULA as blend colour
= 10 for ULA/tilemap as blend colour
= 11 for tilemap as blend colour
= 01 for no blending

bit 6: 0 to select the ULA colour for blending in SLU modes 6 & 7 (soft reset = 0) 1 to select the ULA/tilemap mix for blending in SLU modes 6 & 7

4 since core3.1.4: Cancel entries in 8x5 matrix for extended keys
3 ULA+ enable (soft reset = 0)
2 may change (ULA half pixel scroll) (soft reset = 0)
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.

Bits 6-5 determine what colour is used in SLU modes 6 & 7 where the ULA is combined with Layer 2 to generate highlighting effects (Sprite and Layers System Register ($15)).