On Feb 10, 1:06, Iggy Drougge wrote:
> Richard Erlacher skrev:
>
> >The boot drive normally IS at ID=0, however. That's a real convention
> >throughout the SCSI usage. I don't recall ever seeing a system that
would
> >boot, say, from ID=4. Most PC's will promote the ID=1 device to the
boot
> >rank, but not if ID=0 is present but manlfunctioning. YMMV, of course.
>
> IBM, OTOH, goes according to the SCSI standard and boots from the highest
ID
> and downwards.
The standard doesn't require or suggest that. What it does say is that the
highest numbered ID has highest priority, but it means that in terms of
which device has highest priority in getting the controller's attention.
So it's sensible to put devices that mustn't be kept waiting, like some CD
writers or tapes, at high IDs, though it's less important with many modern,
smarter devices with bufferring.
I've never understood why PCs put the controller at ID 7 (highest priority)
since it makes no difference to a controller. Unless you have a system
with more than one controller, where one has to catch the other's
attention, like a couple of multihost SCSI systems I've seen.
> Besides, everything I've heard about PC SCSI seems utterly ridiculous and
> stone-age.
:-)
--
Pete Peter Turnbull
Network Manager
Dept. of Computer Science
University of York
Received on Sat Feb 10 2001 - 04:01:04 GMT