Timothy Normand Miller wrote: > On 9/5/07, Mark <[EMAIL PROTECTED]> wrote: > > >> Could you be more specific about how VGA graphics mode memory accesses >> aren't standard reads and writes? I'm reading up on VGA, but I haven't >> got there yet. >> > > Patrick did the research on that, so he'll have to fill in the > details. But basically there are some raster operators that can be > applied, and there's a bitblt buffer of some sort, where we put it in > a mode so that reads and writes cause macro operations. > > All standard VGA graphics modes except 320x200x256 and 320x240x256 go through a multistage "pipeline". You can see a diagram of the read and write pipelines here: http://www.supersecret.org/images/VGA_write_pipe.png http://www.supersecret.org/images/VGA_read_pipe.png
Even the direct mapped modes use banked memory to access more than 64k if available on the card. _______________________________________________ Open-graphics mailing list [email protected] http://lists.duskglow.com/mailman/listinfo/open-graphics List service provided by Duskglow Consulting, LLC (www.duskglow.com)
