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Re: [microsound] computers and DSP



that seems like a great site!

there is another piece in the risc puzzle. risc-processors provide fast 
and simple primitives and rely on the optimizer in the high-level 
compler (like c/c++) to output the instructions in an order which 
really use the resources of the processor in an optimal way.

the compiler has more high level knowledge of the task and can make 
these optimizations really well. if the compiler is good.

that kind of optimization is more difficult with a complex-instruction 
type processor unless you happen to do something that really fits the 
complex instructions well (in a high level langage that fits the 
instructions well).

the coming intel processors (IA64-family) goes beyond risc in this 
particular matter.  the practical usefullness of this has yet to be 
determined.

/jan l.

fredagen den 22 november 2002 kl 06.51 skrev Aaron Ximm:

>> Actually, there's one more important factor.  Motorola chips are RISC
>> (reduced instruction set) type, which means that they perform less
>> instructions for a given calculation.
>
> Actually I think that's backwards ~ RISC chips perform more 
> instructions
> for a given (complex) operation, because they don't have esoteric
> instructions to perform such operations directly.  However they balance
> this by using a fixed instruction word size, or always using a fixed
> number of cycles per instruction (fewer than otherwise).
>
> At least, that's how it works down at the level of RISC chips I 
> program ~
> which are babies.  :)
>
> FWIW there're a lot of great, very lay-readable whitepapers on
> contemporary processor design (including discussions of 'sexy' topics 
> like
> symmetrical multiprocessing, 'hyperthreading', altivec, pipelining,
> out-of-order execution, etc ad nauseum) at www.arstechnica.com ~ one of
> the guys who runs the site is a serious CPU hack...
>
> Best,
>
>  aaron
>
>   ghede@xxxxxxxx
>   http://www.quietamerican.org
>
>
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