Author: William Bryant
Date: 07:33:08 10/05/99
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Will, There was a nice summary of the AltiVec capabilities in MacTech magazine about 1 to 2 months ago. It was written by Tom Thompson and probably would have been a Byte article if that magazine was still in print. I can fax it to you. Basically, you need to enable the AltiVec instructions in the compiler. Codewararior 5 supports the AltiVec instruction set and even has support to emulate AltiVec on older G3 machines (which will be slow) until G4s are available. The internal Bus is 128 bits and it can do a lot of bit mangling as simple instructions. There is the potential for a lot of complex vector operations as Bob described if you can a) understand the Altivec instruction set, b) understand how to add vector operations to create a more complex eval, and c) take advantage of the very fast internal 128 bit bus. Note, I think it's still a 32 bit main memory bus at 100 mhz and a 1/2 speed L2 catch at 1 meg. BTW, I you do get a G4, allow me to drool a little in your direction. William wbryant@ix.netcom.com On October 04, 1999 at 20:03:52, Will Singleton wrote: > >I'm looking at the specs for the 500mhz G4 (available someday), and I'm >wondering about a couple things. > >The AltiVec, or "Velocity Engine", is apparently a vector processing unit for >which special code must be written to obtain speedups. I wonder if this means >that the compiler must support those instructions, or can you take advantage of >vector processing just by rewriting existing code? > >Is the vector-processor used mainly in FP operations, or can it be helpful for >integer-based code? > >The specs say that it has data stream prefetching ops supporting 4 simultaneous >32-bit data streams, as well as a new fpu supporting single-cycle, >double-precision calcs. Are both of these associated with the vector processing >unit? > >In short, can a chess program take advantage of vector processing without a >massive rewrite? > >Will
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