[Ham-Computers] RE: SATA

[WA5CAB at cs.com]

Loren,

To add one further point to what Aaron wrote, consider the physical layout of 
the commonly used parallel cables versus the serial ones.  Laid out flat in a 
straight line, the parallel ribbon cable is pretty predictable, although 
specs on the outer wires will be slightly different from the inner ones.  But you 
can fold, bend and otherwise mutilate the ribbon as it is stuffed into the 
box.  If you Z-fold a ribbon to shorten it you add feed-forward capacitance 
between those wires lying closest together.  If you fold it the long way to get it 
through a hole, you add a small shunt capacitance between wires.  Etc.  So in 
the practical case, the actual parameters of the cable are much more variable 
from installation to installation than with a small diameter round serial 
cable.  And at a gigahertz this becomes significant in terms of the bit timing 
problems Aaron mentioned.  Among other things, it varies the velocity factor of 
each wire in a totally unpredictable manner.

Robert Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480
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