Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!wuarchive!uunet!dev8.mdcbbs.com!rivero
Newsgroups: comp.sys.amiga.graphics
Subject: Re: Liquid TV ?  I'm hooked!
Message-ID: <1991Jun12.144902.1@dev8.mdcbbs.com>
From: rivero@dev8.mdcbbs.com
Date: 12 Jun 91 14:49:02 GMT
References: <1991Jun10.091609.8677@crash.cts.com>
Organization: McDonnell Douglas M&E, Cypress CA
Nntp-Posting-Host: dev8
Nntp-Posting-User: rivero
Lines: 37

In article <1991Jun10.091609.8677@crash.cts.com>, seanc@pro-party.cts.com (Sean Cunningham) writes:
> In-Reply-To: message from jet@karazm.math.uh.edu
> 
>  
> Regardless of the number of FPUs, those 64,000 integer units make a big
> difference as well.  And according to one article written about the CM,
> each processor is assigned to an individual pixel.
>  

  Close, 64000 pixels is a display that's only about 250x250 by 8
bitplanes deep. The way the CM is set up, you can assign a "virtual
processor" per pixel onto the high resolution device, but that loads
several pixels onto each seperate processor.

  Also recall that the CM is a SIMD machine, which means that if a
particular pixel is not affected by the current instruction, that processor
sits idle. There are no asynch operations on the CM or CM2.

  Also, while the CM is blindingly fast for problems with small isolated
data sets, it really slows down for applications (such as rendering)
where each processor has to traverse a large dataset. Because the 64000
integer processors are also the packet switchers for data communication, you
can get into situations where 70% of the CM speed is used up just shipping
the data around.

  For Mandelbrots (small localized data sets) it was amazing to watch. But for
rendering and ray-tracing, the performance gain is not worth the cost. 



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