🚀 go-pugleaf

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
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