Hi,

I'm trying to get some graphics going on the Prizm. Currently, i'm drawing to a lump of memory, then copying it to the VRAM and dispDD. This is probably not the fastest way.

For example, is there some way to double buffer the screen. can the screen address be changed with a SYSCALL. or maybe there is something already for this problem.

thanks for any help,
-- hugh.
Just the fact that the screen has its own internal buffer aside from VRAM means that you can draw directly to VRAM every frame and then copy to the screen, which is inherently a form of double buffering. Get what I mean?
Yes, currently im doing an additional copy, which is bad. is the VRAM just an area of the normal ram, or is is slower in some way. eg RAM on the LCD controller or something.

additionally, there is still the internal copy it must be doing of, presumably, 162k for each frame.
VRAM is just normal RAM, and the dispDD function copies all of the data from this RAM to the LCD's internal display RAM. The LCD's RAM is not memory-mapped, so you can't draw to it directly.
understood, thanks calc84maniac.
You can use http://prizm.cemetech.net/index.php?title=Bdisp_SetPoint_DD to set a pixel directly, bypassing the VRAM. Check out http://prizm.cemetech.net/index.php?title=Display for more info on the display.
Keep in mind that such functions are much slower than writing and copying the VRAM if you're drawing any significant number of pixels (and it doesn't double-buffer at all, pixels appear as you draw them)
basically, im updating the whole screen each frame.
Then you're better off writing it all to VRAM and then calling Bdisp_PutDisp_DD(), since the LCD driver uses nice, fast DMA to get that contents onto the screen.
  
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