Re: Listen up: 15 fps and slot 3.

[bazyar@netcom.com (Jawaid Bazyar)]

toddpw@pride.ugcs.caltech.edu (Todd P. Whitesel) writes:

>I honestly do not know where Jawaid is getting that 15 fps figure. It must
>be an absolute worst case scenario -- 2 60 hz frames to send up a full SHR
>screen image with DMA, then another two frames to guarantee the SS video
>displays all of the new image at least once? That is really pessimistic
>in terms of other programs, which is what most people are probably thinking
>of here. When Jawaid says 15 fps, everybody else thinks "oh my god, it
>must look like finder does when I leave Normal Speed turned on in the
>control panel". It won't.

  Todd, thank you. You're 100% correct, except your guess as to the
source of the frame rate.
  The SS _CURRENTLY_ is able to convert 32K of SHR data into 128K of
VGA data 15 times a second. Shadowing occurs so infrequently that
we do it in the background (BREQing the Z180) with no noticeable
slowdown on the Z180. The Z180 has to do some rather complicated
load, table lookup, read word, and store operations to do the 
16->256 color conversion.

  Yes, if I could sync the two video systems, the tear could
be avoided, but I can't. 
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