[RC5] Checking a bad proc..

Dennis Lubert plasmahh at gmx.net
Wed Jan 8 19:30:15 EST 2003


At 05:23 08.01.2003 -0500, you wrote:
>CPU's are transistor devices, and after 40 some years of dealing with 
>them, they either work as advertised, or theyre dead. There is no middle 
>ground. It sounds like there are other problems, as I have never 
>seen/heard of a partial failure of a CPU...

Modern CPUs are very complicated devices, and using them does not always 
use every little part of it. In fact floating point operations very often 
use some kind of tabling for low-level operations. For common operations 
they do not use everything of those circuits. (As most might remember there 
was an issue with the early Pentium CPUs when in very rare circumstances 
the FPU returned false values). I have seen some CPUs with damaged FPU and 
even some vector processors that did  not work properly. All those were 
working fine in usual OS environments, but failed when doing some special 
operations. Those special circuits are very hard to check on Hardware base 
sometimes (like for tabling you must either have a calculatable table or a 
second one). But at least the x86 processors have very good check circuits 
for the integer and memory operations, that prevent the CPU from booting in 
case of failure. So I personally think that if a CPU runs, then it will run 
on RC5 as well, since it does only use integer arithmetics afaik.

greets

Dennis

PS: According to the AMD spcifications their processors have their 
hot-spots at the FPU and Multimedia instructions. 

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