Re: PATCH: Different SCSI ordering for WIDE SCSI chains.

Kurt Garloff (garloff@kg1.ping.de)
Thu, 26 Nov 1998 20:10:26 +0100

On Thu, Nov 26, 1998 at 07:44:22AM +0100, Rik van Riel wrote:
> On Wed, 25 Nov 1998, Rolf Fokkens wrote:
>
> > Furhermore I heard that non-wide take actually two ID's when
> > connected on a WIDE chain: the configured ID and that ID+8. They can
> > be addressed by their own ID, but the other ID is lost.
>
> They don't. SCSI uses a separate piece of wiring (actually
> just the data wires) for each ID.

Too explain this in more detail: When the SCSI Controller selects a device,
it uses one of the 8 (narrow) or 16 (wide) data lines to signal the device.
That's why SCSI supports only 7/15 devices plus controller and not 255/65535!
You don't have those narrow/wide problems: The narrow devices wont't
feel selected, because they don't even see the data line ...

-- 
Kurt Garloff <K.Garloff@ping.de>  (Dortmund, FRG)
PGP key on http://student.physik.uni-dortmund.de/homepages/garloff


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