Re: Hard drive cable question -

Mike McCarty:
If you use M/S jumpering on the drives, then in theory it doesn't matter
where you connect them.

bobgoodwin:
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.

Theoretically, you should terminate the cable at both ends with
something. I would expect to see problems with a cable flapping about.
I've seem old IDE systems wired up in all sorts of ways without
problems. I've seen systems come in with problems, but you're never
quite sure if just fiddling with the cable fixed things, rather than
changing the position, unless you prove the cable is intermittent by
repeatedly poking it about.

If it seems slightly dodgy I'll replace it, they're so cheap and it's
not worth the headaches. Most cables aren't meant for repeated plugging
and unplugging anyway, so if you've got a fiddler's broken box on your
hands, there's a very good chance that they've worn out the contacts, or
wrenched the ribbon out of the IDC connector teeth.

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 ...

You'd have to be careful that the measurement, itself, doesn't affect
the readings; which is quite likely with such high speed data. You'd
also need to know how much ringing was tolerable by the specs, anyway.

If the h/d manufacturer provided this explanation this thread would
never have started. I would have never asked any questions. It appears
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?

Yes, it doesn't help when you get unlabelled jumpers on drives, new
drives in a bag with no instructions, and manufacturers with useless
websites.

I have yet to find a system that won't work with manual jumpering, and
it's what I always use. If it works, there's no point in caring if the
cable is cable-select. If it doesn't work, you've only got a few
variations that you need to try. But I'd be most suspicious of: (a)
crap cabling which ought to be replaced, and (b) a broken drive which is
likely to cause you other grief, too.

Probably the worst aspect to jumpering drives is finding out that you
need two jumpers in the block, for your situation, but the damn
manufacturer only supplied one!

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