Hard Drive Error Disk or Motherboard?

Gene Heskett gene.heskett at verizon.net
Tue Nov 21 17:04:56 UTC 2006


On Tuesday 21 November 2006 09:33, Mel wrote:
>Alan wrote:
>>   Controller<=====Longest Part of cable===>Drive2<===Short
>> bit===>Drive1
>
>If I remember my cable theory correctly, all cables should be terminated
>in their characteristic impedance at both ends. If not, then reflections
>occur.
>
>The higher the frequency, the greater effect they have on reliable use
>of the cable. As you said, cable length is also a factor.
>
>Isn't this what "Time Domain Reflectromitry(SP?)" is based on?

The spelling will do, its reflectrometry, and the answer is yes.  The 
problem is that to do it on cables as short as the 18 inchers used for 
ide connections, it takes some very expensive versions of it since one 
must be able to see, and detect an anomoly thats only 1/8" wide.  There 
are fast samplers, and there are damn fast samplers.  For longer stuff, 
I've used just a schotkey ttl gate as the signal, and a 100mhz scope to 
read it.  There I can see with an accuracy of maybe 10 feet over 500 with 
that simple a lashup.  With the real thing, I can see the individual 
connectors and insulators in a length of 3.125" transmission line but I 
can only see burnouts with my simple lashup because its not fast enough 
by a factor of 100 or so.
-- 
Cheers, Gene
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