Path: utzoo!utgpu!attcan!uunet!cbmvax!daveh
From: daveh@cbmvax.UUCP (Dave Haynie)
Newsgroups: comp.sys.atari.st
Subject: Re: NeXT announcement (was Re: Atari Workstation)
Message-ID: <5101@cbmvax.UUCP>
Date: 25 Oct 88 17:50:35 GMT
References: <2893@sugar.uu.net>
Organization: Commodore Technology, West Chester, PA
Lines: 47

in article <2893@sugar.uu.net>, peter@sugar.uu.net (Peter da Silva) says:

> In article <9236@watdragon.waterloo.edu>, jafischer@spurge.waterloo.edu (Jonathan A. Fischer) writes:
>> It (the ATW)
>> supposedly has this blindingly fast blitter / graphics coprocessor /
>> whatever.  Since no such thing was mentioned in the NeXT press release, I'm
>> assuming that the graphics load is handled by the '030.  A big lose.

> Not necessarily. 

True, but...

> According to Henry Spencer the 68030 can run a BitBlt in cache fast enough that 
> there's one useful memory reference every clock cycle.

The 68030 can't run a memory cycle every clock cycle under any conditions.  It CAN
run a memory cycle every 2 clock cycles, and it can burst fill 4 longwords into
the cache in 5 clock cycles, which will probably be as fast as any reasonable
memory system will go.  Just figured I'd clear that up.

> This is also the maximum speed a DMA device can be expected to support. Thus,
> a 68030 cannot be speeded up by a Blitter. 

Certainly a blitter isn't going to do many things faster than a 68030
would, on the same bus.  So put a high level blitter on a separate bus
from the 68030.  Especially if all your output is in terms of a
relatively high level language like PostScript.  So instead of having
the 68030 draw a particular scaled and filled character, you send the
blitter the position and character code.  It does the filling, scaling,
and rendering while your '030s off doing other stuff. 

This isn't the blitter we use in 16 bit systems today.  Then again, the 68030
isn't a 68000.  This blitter COULD be another 68030, or a 34020, or an 8500
system.  If done right, it wouldn't matter, either, you just get a faster 
display with a faster rendering engine.  

See the blitter wars in comp.arch
> for more details.
> -- 
> 		Peter da Silva  `-_-'  peter@sugar.uu.net
> 		 Have you hugged  U  your wolf today?
> 
> 	Disclaimer: I accept full responsibility for my own typos.
-- 
Dave Haynie  "The 32 Bit Guy"     Commodore-Amiga  "The Crew That Never Rests"
   {uunet|pyramid|rutgers}!cbmvax!daveh      PLINK: D-DAVE H     BIX: hazy
              Amiga -- It's not just a job, it's an obsession