SW>Recycling a Message by _Marc Melvin@1:110/1065.0_ to
SW>_All_ (Date: 09.07.97)
MM> though I have to use this 30 line code to just draw a pixel... well,
SW>I
MM> would appreciate it if someone could help me out here... assigning
MM> $A000:0000 to 255 doesn't work with 640x480... yipes... :)
SW>The problem is that mode 12h (640x480x16) uses planes. The VGA-RAM is
SW>divided into 4 Planes, each containig 1 Bit of all pixels. When the DAC
SW>has to write the pixel onto the screen it reads out all 4 planes to get
SW>the 4 bit color-number.
SW>When you want to write a pixel you have to switch planes and write each
SW>single Bit of the color! So putting a pixel in 640x480 is a rather slow
SW>procedure :-( and the 30 line code you use appears to be a good
SW>approach...
SW>To speed things up you can use a virtual screen and write a whole
SW>bitplane
SW>before swithing to the next plane.
I think he was referring to 640x480x8bit not the 4bit modes.
... Hey! Your Trackball is upside down!
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