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I'm looking through ATA/ATAPI-6 Annex (A.) and there's a chart for 
40-wire cabling indicating various minimum and maximum length 
restrictions in table A.4, along with the statement "Cable 
capacitance shall not exceed 35pf."

The chart is not particularly clear as to the allowable limits for a 
single device cable.

Even more troubling is the lack of any explanation electrically for 
establishing the minimum length wiring allowed.

There is somewhat more information in the 80-wire tables, but there's 
no justification given for the minimum host-to-device distance of 5 
inches.

Since there are plenty of good reasons to build things with shorter 
cables, what are the specific parameters to be accounted for in 
establishing the minimum length?

I know the limitations of going longer have been argued and covered 
reasonably well.
-- 

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I make stuff go.
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Larry Barras
Apple Computer Inc.
1 Infinite Loop
MS:  306-2TC
Cupertino, CA  95014
(408) 974-3220

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