AHA2790UW has speed-limit problems ?

[Mike Bilow]

Doug Ledford wrote in a message to Mike Bilow:

 DL> The cable run
 DL> from the card to the last device needs to be as free of
 DL> twists and turns as possible.  The more you can straighten
 DL> that cable out, the better.  In general, I find that loops
 DL> don't cause any problems  but that twists are horrible for
 DL> reliability.  IOW, if you fold the cable with a sharp crease
 DL> such that pin one on the cable ends up laying against pin
 DL> one on the cable, that's OK, when there is a twist such that
 DL> pin one on the cable ends up running past or parallel to pin
 DL> 68 of the cable, that's bad. 

When you are dealing with old-style flexible ribbon cable, the best way to make
a turn is to fold the cable cleanly at a mitred corner, so that the conductors
are as much at right angles to each other as possible.  This is impossible with
the newer, more rigid "SCSI-3" cables, however.
 
-- Mike



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