Fix graphics format: Difference between revisions

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The [[fix layer]] uses 8x8 pixels tiles, coded in a 4BPP linear format with mixed columns.
The [[fix layer]] uses 8x8 pixels tiles. They're coded in a 4 bits per pixel, linear format with oddly mixed columns. Pixels are coded by pairs as bytes, in columns from top to bottom.
 
Note that the pixel positions are swapped in each byte (the left pixel goes in bits 0~3, the right pixel goes in bits 4~7), and that the first stored column is column A.
 
[[File:fixgfx.png|center]]
 
=Size=
 
One tile is 8 * 8 pixels * 4 bits per pixel = 256 bits = '''32 bytes'''.
 
=ROM addressing=


<pre>
<pre>
10a 10b 18a 18b 00a 00b 08a 08b
Bit # ...543210
11a 11b 19a 19b...
      ...nHCLLL
 
n: Tile number (multiple bits)
H: Half, 0 = right, 1 = left
C: Column in half, 0 = left, 1 = right
L: Line number (0~7)
</pre>
</pre>


a=low nibble
{{Sig|2H1|2H1}} is "C".
 
(Need diagram).


[[Category:Video system]]
[[Category:Video system]]

Latest revision as of 09:51, 26 June 2017

The fix layer uses 8x8 pixels tiles. They're coded in a 4 bits per pixel, linear format with oddly mixed columns. Pixels are coded by pairs as bytes, in columns from top to bottom.

Note that the pixel positions are swapped in each byte (the left pixel goes in bits 0~3, the right pixel goes in bits 4~7), and that the first stored column is column A.

Size

One tile is 8 * 8 pixels * 4 bits per pixel = 256 bits = 32 bytes.

ROM addressing

Bit # ...543210
      ...nHCLLL

n: Tile number (multiple bits)
H: Half, 0 = right, 1 = left
C: Column in half, 0 = left, 1 = right
L: Line number (0~7)

2H1 is "C".