Difference between revisions of "ULA Control Register"

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|Readable=Yes
 
|Readable=Yes
 
|Writable=Yes
 
|Writable=Yes
|ShortDesc=Disables ULA completely and controls its mixing with Tilemap layer.
+
|ShortDesc=Disable ULA, controls ULA mixing/blending, enable ULA+
 
}}
 
}}
 
{| class="wikitable"
 
{| class="wikitable"
 
! Bit !! Function
 
! Bit !! Function
 
|-
 
|-
| 7 || 1 to disable ULA output
+
| 7 || 1 to disable ULA output (soft reset = 0)
 
|-
 
|-
| 6 || 0 to select the ULA colour for blending in SLU modes 6 & 7
+
| 6-5 || since core3.1.1: Blending in SLU modes 6 & 7 (soft reset = 0)
1 to select the ULA/tilemap mix for blending in SLU modes 6 & 7
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= 00 for ULA as blend colour
 +
= 10 for ULA/tilemap as blend colour
 +
= 11 for tilemap as blend colour
 +
= 01 for no blending
 +
<del>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</del>
 
|-
 
|-
| 5-1 || Reserved, must be 0
+
| 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
 
| 0 || 1 to enable stencil mode when both the ULA and tilemap are enabled
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|}
 
|}
  
Bit 0 can be set to choose stencil mode for the combined output of the ULA and tilemap.
+
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.
+
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 ({{NextRegNo|$15}}).

Latest revision as of 01:08, 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)).