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Re: Hard drive cable question -



On Thu, 2006-02-23 at 21:35 -0500, Gene Heskett wrote:
> On Thursday 23 February 2006 16:18, Mike McCarty wrote:
> >bobgoodwin wrote:
> >> Mike McCarty wrote:
> >>> bobgoodwin wrote:
> >
> >[snip]
> >
> >>> If you use M/S jumpering on the drives, then in theory it doesn't
> >>> matter where you connect them.
> >>
> >> Except it appears to me that it matters as far as terminating the
> >> line properly is concerned.  Ideally it would seem the termination
> >> should be at the far end where the master is connected to avoid the
> >> possibility of a mismatch at the end of the stub that would result
> >> if the slave is at the far end.  How much ringing might occur and
> >> the severity of it's effect is an unknown?  It would be interesting
> >> if I could get into the circuit and poke around with a scope probe
> >> ...
> >
> >Agreed.
> >
> >[snip]
> >
> >>>> I thought "cable select" cables had wires obviously crossed in the
> >>>> ribbon cable but that may not be true with this 80 wire ribbon?
> >>>
> >>> Not crossed. For CS, the drives have resistive pull-ups on them.
> >>> The MB pulls down one line. The wire to this line is *severed* as
> >>> the slave connector, so the "master" sees a high, while the "slave"
> >>> sees a low on this pin. (The MB may have a pull-up and the drives a
> >>> pull-down, I forget the polarity.)
> >>
> >> If the h/d manufacturer provided this explanation this thread would
> >> never have started.  I would have never asked any questions.  It
> >> appears
> >
> >Well, just how much of the interface should they document? Each pin?
> >Just the Cable Select pin?
> >
> >> that I probably have cable select which I will try here in a little
> >> while.  The drives can be jumpered for CS and I have 80 wire ribbon
> >> cables so it appears that should work if I understand everything
> >> I've read here?  It would be helpful if the user knew that he was
> >> dealing with a c/s cable, there is no mark apparently other than the
> >> fact that there are more wires than connector pins to tie them to?
> >
> >Color of the connectors. Usually non-CS cables use just one color
> >of connector, presumably because they can get better volume
> >prices that way. CS cables are supposed to use blue for the MB
> >connector, black for "master" and grey for "slave", IIRC.
> 
> And someone else quoted the last two in reverse.  Can someone PLEASE go 
> get one of these friggin cables and settle the argument?  Good color 
> vision required of course :)

Definitively, and as was already quoted from the specs for these cables.

Black is the master connector (on the end)
Grey is the slave connector (middle but nearer to the black)
Blue is the motherboard connector (on the other end) (blue is the
specified color but manufacturers do use different colors)

I have seen several with different colors at the board end, but always
the black and grey are correct. The one I just got with my new Giga-Byte
motherboard is green on the board end.


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