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From: rodent@netcom.COM (Ben Discoe)
Newsgroups: sci.virtual-worlds
Subject: Re: Real-time raytrace -- get serious!
Message-ID: <1991May16.055359.2823@milton.u.washington.edu>
Date: 16 May 91 02:53:35 GMT
References: <1991May15.050715.28438@milton.u.washington.edu>
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cdshaw@scapa.cs.ualberta.ca (Chris Shaw) writes:

> Filip Gieszczykiewicz writes:
>
>> Greetings. Well, I finally got my 486/25 (25MHz)
>> Real-time raytracing is not as far away as most of you led me
>> to believe.... 
>
>Whoa, there. That's quite a simple model you traced!
>So fine, you got a simple model, a fast-ish CPU, a small screen, and 
>it takes 2 minutes. To get 0.5 seconds (the absolute minimum)
>you need a speedup of 2*60*2 = 240. Just buying 240 486/25's is 
>going to cost you $500,000 !!

Everyone knows parallel's the way to go.  No, buying 240 expensive
CPUs isn't the right way - but buying a rack of cheap CPUs is an option
that i think has some promise.  68000s are cheap, and you could probably
(easily) find some other not-currently-hot chip that provides even
better processing/dollar.  A hardware rack could be built to handle
as many cheap CPUs as you could buy - the bus only needs to handle
minimal data.  With 64 68000s you spend around $350 for the CPUs and
probably $500 for the bus, rack and glue hardware.  Of course this doesn't
include design costs... but when people are spending $4000 to $6000
on fancy MacIIs and Amiga3000s to get the raytracing-power of 15-20
68000s, you realize there is a ready market for an open-ended "raytracing
box" that could handle N cheap CPUs.  Of course, giving each processor
it's own memory would be necessary and reasonably expensive... but
you could download different parameters and get extremely fast mandelbrot
sets from the same hardware.  I think this could be done at a final
cost of less than $2000, even less in kit form.

This gives us something to do with those millions of old CPUs going out
of date.  OK now, somebody tell me this is all silly.

-------------------
Ben Discoe, radical ecologist, computer scientist, visionary at large.