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Re: FrameThrower vs CAD Buffer II for XL1200 color graphics?

    Date: Thu, 15 Nov 90 09:45:05 -0500
    From: kanderso@DINO.BBN.COM

      Date: Wed, 14 Nov 90 11:06 PST
      From: DDYER@riverside.scrc.symbolics.com
      Subject: FrameThrower vs CAD Buffer II for XL1200 color graphics?
      To: Marty Hall <hall@aplcen.apl.jhu.edu>, slug@ai.sri.com
      cc: gdoc%WHITE@warbucks.ai.sri.com
      Fcc: W:>ddyer>mail.sent.newest
	  Date: Wed, 14 Nov 90 09:36:39 -0500
	  From: hall@aplcen.apl.jhu.edu (Marty Hall)
	  Does anyone have any experience in the performance advantages of the
	  FrameThrower board vs the regular CAD Buffer II for normal Symbolics
	  color graphics on an XL1200? By "normal" I am talking about using functions
	  in the Symbolics color system or just graphics:draw-xxx with :color
	  arguments, not anything with any of the S-products, HDTV, etc. We are
	  looking to speed up things like reopening windows, popping up menus,
	  drawing/animating simple graphics, etc, that take place on the color screen.
	  Ie the FrameThrower board is designed to do much more than act as a 
	  color graphics accelerator, but if it were used in that role, does
	  anyone know what kind of a performance benefit there would be?
	  Our local sales rep thought "significant" (or were they thinking of
	  the price? :-), but was a bit fuzzy.
      Just by having a 1200 things get faster by a factor of 3, so any overhead-dominated
      operations (such as drawing zillions of small things) get faster by 3.   

    It may be that in general an XL1200 is 3 times an XL400.  But, it has
    been our observation that drawing lines on a color XL400 in genera 8.0
    is twice as SLOW as drawing in color on a 3640.  So the performance
    advantage may only be about 1.5.

Line drawing, especially in color, was one of the places where Ivories
looked poor.  Raw line drawing speed got about twice faster in 8.0.1.

Other than that specific, you're correct to observe that raw speed of
color drawing on Ivory machines was significantly slower than on 36xx,
due to limitations of the color hardware available on Ivories.  However,
fixed overhead per operation is the majority of the cost in most real
applications, so I'd generally stick to 3 as the starting guestimate.

Of course, the speed of operations problem is fixed, and then some, by