Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!usc!cs.utexas.edu!uunet!sjsca4!news From: greg@bilbo (Greg Wageman) Newsgroups: comp.sys.atari.st Subject: Re: More Performance Specs Message-ID: <1989Aug3.201227.18486@sj.ate.slb.com> Date: 3 Aug 89 20:12:27 GMT References: <15602@watdragon.waterloo.edu> Reply-To: greg@sj.ate.slb.com (Greg Wageman) Organization: Schlumberger ATE, San Jose, CA Lines: 40 In article <15602@watdragon.waterloo.edu> achowe@tiger.waterloo.edu (CrackerJack) writes: > >Blitter QUICK ST BIOS BIOS Scroll GEM > Text String >---------------------------------------------------------- >no no 98 98 100 99 >yes no 106 103 130 128 >no yes 140 427 127 108 >yes yes 140 427 127 146 > >From what Darek has told me, QUICK ST is self-modifying assembler code >that does what the C written TOS code does. What I don't understand is >why the scroll test is a tad slower with QUICK ST on. The blitter does >improve graphics speed on the Mega. But with QUICK ST and a blitter we >can see that graphics could be faster still. Not having seen the sources, this is only an educated guess; however, it fits the facts as I know them. If QuickST is intercepting certain traps into TOS, and replacing the underlying routines with its own, it's possible that calls which would normally exercise the blitter never get there when QuickST is installed. Remember that no applications code has to change to make use of the blitter; "Blitter-TOS" uses the chip if it exists and otherwise performs the blits in software. Now if QuickST replaces some (many?) of these routines, and doesn't itself use the blitter, then having a blitter won't help except on calls that QuickST doesn't trap that do use the blitter. This seems to be the case with some GEM calls. Darek & Co. could probably get still better performance if they wrote a version of QuickST that uses the blitter... Greg Wageman DOMAIN: greg@sj.ate.slb.com Schlumberger Technologies UUCP: ...!uunet!sjsca4!greg 1601 Technology Drive BIX: gwage San Jose, CA 95110-1397 CIS: 74016,352 (408) 437-5198 GEnie: G.WAGEMAN ------------------ Opinions expressed herein are solely the responsibility of the author.