Difference between revisions of "Clip Window Control Register"

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(added info + Core 2.00.22 changes (readable now))
 
(fix description for core3.1.5 functionality)
 
(5 intermediate revisions by 2 users not shown)
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|ShortDesc=Controls (resets) the clip-window registers indices.
 
|ShortDesc=Controls (resets) the clip-window registers indices.
 
}}
 
}}
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Write:
 
{| class="wikitable"
 
{| class="wikitable"
 
! Bit !! Function
 
! Bit !! Function
 
|-
 
|-
−
| 7-3 || Reserved, must be 0
+
| 7-4 || Reserved, must be 0
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|-
 +
| 3 || reset the Tilemap clip-window register index (by writing 1).
 
|-
 
|-
 
| 2 || reset the ULA/LoRes clip-window register index (by writing 1).
 
| 2 || reset the ULA/LoRes clip-window register index (by writing 1).
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|}
 
|}
  
−
Ped7g comment: it's a bit unclear what interesting info may be gained by reading this register (seems a bit useless to me). I posted question in forum and I will update the text if I will get explanation.
+
Read:
 +
{| class="wikitable"
 +
! Bit !! Function
 +
|-
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| 7-6 || the current Tilemap clip-window register index
 +
|-
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| 5-4 || the current ULA/LoRes (<del>was Layer 2 in older cores</del>) clip-window register index
 +
|-
 +
| 3-2 || the current Sprite clip-window register index
 +
|-
 +
| 1-0 || the current Layer 2 (<del>was ULA/LoRes in older cores</del>) clip-window register index
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|}
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 +
Each read index maps as 0: X1, 1: X2, 2: Y1 and 3: Y2 (the same order how the coordinates are written to particular clip-window register).

Latest revision as of 20:38, 23 September 2020

Number $1C
Readable Yes
Writable Yes
Short Description Controls (resets) the clip-window registers indices.

Write:

Bit Function
7-4 Reserved, must be 0
3 reset the Tilemap clip-window register index (by writing 1).
2 reset the ULA/LoRes clip-window register index (by writing 1).
1 reset the Sprite clip-window register index (by writing 1).
0 reset the Layer 2 clip-window register index (by writing 1).

Read:

Bit Function
7-6 the current Tilemap clip-window register index
5-4 the current ULA/LoRes (was Layer 2 in older cores) clip-window register index
3-2 the current Sprite clip-window register index
1-0 the current Layer 2 (was ULA/LoRes in older cores) clip-window register index

Each read index maps as 0: X1, 1: X2, 2: Y1 and 3: Y2 (the same order how the coordinates are written to particular clip-window register).

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