Path: utzoo!attcan!uunet!lll-winken!lll-lcc!ames!joyce!sri-unix!hplabs!nsc!voder!apple!tecot
From: tecot@Apple.COM (Ed Tecot)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Fake Color Quickdraw (was Re: a whole bunch of things)
Message-ID: <14111@apple.Apple.COM>
Date: 17 Jul 88 01:54:54 GMT
References: <227@hodge.UUCP> <3988@pasteur.Berkeley.Edu> <5212@batcomputer.tn.cornell.edu> <46753DN5@PSUVM> <13829@apple.Apple.COM> <390@umn-d-ub.D.UMN.EDU> <13954@apple.Apple.COM>
Reply-To: tecot@apple.apple.com.UUCP (Ed Tecot)
Organization: Apple Computer Inc, Cupertino, CA
Lines: 24

In article <13954@apple.Apple.COM> dgold@apple.apple.com.UUCP (David Goldsmith) writes:
>Unfortunately, Ed Tecot was guilty of a slight typographical error.  Patching
>Color QuickDraw onto the Mac Plus or SE would require:
>
>1) Rewriting it, since it uses 68020 instructions for speed in dealing with
>   multibit pixels.
>2) About 200K to 250K of memory.

David's right if you want full Color Quickdraw, that is, something that
you could use with a card connected to a color monitor.  My discussion in
my previous two messages assumes a b/w Quickdraw with a color interface.
I didn't even consider multi-bit offscreen pixmaps.  If you want that, add
a lot more code and expect real poor performance.  CQD takes advantage of
the 68020 in such a way that it is more 3 times faster than a 68000 at the same
clock.  (FYI - normal 68000 code is only twice as fast on a 68020 at the same
clock, and only if it is memory intensive).

>3) Since CQD uses traps outside the range of the Plus/SE trap dispatcher,
>   the trap dispatcher would have to be patched out.  This would slow it
>   down by about 30% since it would be in RAM rather than ROM.

I didn't even think about that.  I don't think anyone would be willing to
pay that price.

						_emt