Why would drive run at UDMA33? (Segate 80GB)

Dan Strick strick at covad.net
Fri Feb 13 17:55:53 PST 2004

On Fri, 13 Feb 2004 09:58:47 -0500, Jonathan Arnold wrote:
> Also mentioned in this thread was something about the cable being
> connected "backwards". There is no "motherboard" and "disk" connecting
> direction in an IDE cable, be it a reguler one or a UDMA 100 one. Cables
> are made to be a little more convenient if you hook them up the "right"
> way (with two connectors closer together at one end), but it has no
> bearing on the speed or the UDMA detected.

Then on Fri, 13 Feb 2004 11:31:16 -0500, JJB wrote:
> Now on the subject of which end of the IDE ribbon you plug into the
> motherboard. I agree with you that it makes no difference other that
> one end has 2 nipples closely spaced together and if that end is
> plugged into the motherboard it's next to imposable to attach an
> second device to the ribbon. Now if the devices are jumper as master
> ...

Then on Fri, 13 Feb 2004 16:41:08 -0500, Jonathan Arnold wrote:
> I don't think this is true either. I've hooked up a lot of drives
> in my time, and I've never seen this. And no "build it yourself"
> guide that I was able to find on the 'net mentioned anything at all
> about which nipple to plug into the slave or master drive.

It does make a difference with 80 conductor high speed "UDMA" cables.
The motherboard end of an 80 conductor cable is special because one of
the positions in the socket connector is disconnected from the cable so
that the host can tell which kind of cable is attached.  If the cable
is plugged in backwards and the middle connector is plugged into a
drive, the host thinks the cable is a low speed 40 conductor cable.
Another possible problem is that the slave drive cannot correctly
pass the results of its power-on-self-test to the master drive.

Dan Strick
strick at covad.net

More information about the freebsd-questions mailing list