Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!newstop!sun!coherent!next!sstreep
From: sstreep@next.com (Sam Streeper)
Newsgroups: comp.sys.atari.st
Subject: Re: A-Line Solution, AES and VDI
Message-ID: <294@next.com>
Date: 16 Nov 90 21:11:05 GMT
References: <1990Nov6.171858.11434@lsuc.on.ca> <1990Nov14.161216.7677@daffy.cs.wisc.edu> <1990Nov14.133639.1@coral.labmed.umn.edu>
Reply-To: sstreep@elvis.UUCP (My Account)
Organization: NeXT, Inc.
Lines: 39

>> ... I and a few
>> of my friends are pondering just what good a blitter chip actually is on
>> the ST, and if it offers any advantages over the software blitters.	
>
>I can't answer your question directly, but I can point you to the last two
>issues of STart magazine (October, which has 'September' on the cover, and
>November 1990). Both have had programming articles related to the blitter chip
>and demo some of the supposed advantages of the chip.
>David Paschall-Zimbel		davidli@simvax.labmed.umn.edu

I can add a little to this (since I wrote those articles... 8^))
The blitter chip offers a noticable speedup on most graphics operations
like text output.  The software blitters offer a huge speedup of many
operations, but the last time I tried them (admittedly about a year ago)
they still had enough little incompatibilities that I would not use them
full time.  They really made some things (like emacs) super fast and nice
to use, though.

Curiously, the one operation that the software blitters didn't speed up
(in the last versions I saw) was the true blit, the vro_copyfm() function.
For things like this, the blitter chip offers better performance than you
can get from pure assembly language, something like a sixfold performance
increase.

For the best of both worlds, you use both software and hardware blitters,
and your system absolutely screams.  (I'd assume that the latest software
blitters fix the little nits that used to bug me)

On a side note, I ported BoinkOut, the blitter game in November STart,
to the NeXT cube, and it runs about the same speed on a 25MHz 68030 as
it runs on a Mega ST with a blitter chip.  The comparison is not totally
fair, because my cube is running a lot of other tasks (all graphics are
done by a separate window server process, so there's a _lot_ of inter-
process communication) and the NeXT runs a 256Kbyte screen and uses
floating point instead of integers...  Technology buys you a lot, but it
doesn't always buy you speed.

cheers,
-sam  (sam_s@NeXT.com)