[X4U] Re: New Pentium Macs (Altivec)

[John Richardson]

Hello,

Thanks.

I do not consider a vector processor a SIMD computer. My definition is from
the wiki paragraph on History.

"Later machines used a much larger number of relatively simple processors".

This allows the algorithm complexity to be knocked down by an order of
magnitude on suitable algorithms from lets say O(n) to O(logn). Each
processor needs a large amount of memory.

If you have a vector CPU with a large vector length as part of a system and
large numbers of such CPU's and the communications architecture is designed
to distribute data and distribute results to the other CPU's in the system
then you have something resembling a SIMD machine (example: Virginia Tech
Mac cluster). However, I do not consider the PowerPC vectors to be large
enough.

John F. Richardson

-----Original Message-----
From: x4u-bounces at listserver.themacintoshguy.com
[mailto:x4u-bounces at listserver.themacintoshguy.com] On Behalf Of Kuestner,
Bjoern
Sent: Thursday, January 26, 2006 12:38 AM
To: 'A place to discuss Mac OS X for the casual user.'
Subject: RE: [X4U] Re: New Pentium Macs (Altivec)

> Does anyone manufacture a SIMD computer?

Both SSE and Altivec units implement SIMD (or vector processing).

If your question is whether one computer architecture specifically focuses
on SIMD vs. having it just as a mere add-on: Cray was a big name in this
area. Now NEC is. Also DSPs are implementations of stand-alone SIMD
processors.

As usual in IT issues, Wikipedia is a good reference:
http://en.wikipedia.org/wiki/SIMD
http://en.wikipedia.org/wiki/Vector_processor
http://en.wikipedia.org/wiki/Digital_signal_processor

Björn

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