The ID jumpers on SCSI devices are usually, but not always, labelled as
powers of 2.  So zero is 2 to the power of zero, or 1 in decimal, and
1 is 2 to the power of 1, or 2 in decimal, and 2 is 2 to the power of 2 or
4 in decimal.  You add the decimal values of the pins that are covered to
get the ID.  So if you cover zero, your id is 1.  If you cover 2 and zero,
your id is 5.  If you have a wide device, you will have a fourth pin which
is 2 to the power of 4 or eight in decimal.
There is no special significance to the zero ID anymore.  On some old SCSI 8
bit
cards the BIOS was not configurable except through a loaded device driver.
Since
you need a config.sys to load a device driver in dos, the BIOS was
hardwired to check ID zero for a bootable device, thereby enabling at least
one fixed disk from which to load device drivers.  This is an
over-simplistic
explanation, of course.  In my UNIX days, the tape device was the first
bootable
drive, but then you don't boot UNIX very often, so let's skip that.
Anyway, you can configure any device to boot, with the caveat that ID 7 is
the controller by default, and this should not be changed.
I prefer to boot from device 6, since such a high id has bus priority over
lower
id assignments.  Set your scanner and backup device to be the lowest ids,
since
they do not need priority over disks.  Having said that, my real world
experience
is that it is very hard to generate on a desktop the kind of bus traffic
that would benefit
from carefully mapped id numbers designed to take advantage of the priority
rule,
and my servers do not have slow devices attached, period.
As for the original issue of this thread, I would reset the controller to
factory
defaults.  Sounds like you have termination issues.  You should not need to
low-level
format, a regular format should suffice if you want to clear the disks.
The controller termination must be set to auto.  The fact that your IBM id
is unexpected
may be because you have mis-identified the jumpers.  The long delay in
booting
may be because the termination power is incorrectly set, it can be supplied
by device or by
bus.  Again, leave it set to factory default unless you have specific
recommendations otherwise.
There also is no harm in leaving all id's set to auto in regards to width
and speed, the controller will adjust to the settings required when it gets
the device identification response.
Tom Turak

-----Original Message-----
 Here is where I now stand in trying to install two Seagate 4.5 UW Cheetahs
 and the one 4.5 UW IBM drives in my system. The are Seagate 1, ID 0, boot,
 Seagate 2 ID 1, and for some reason the IBM shows up as ID 4, even thought
 the jumper is at ID 2.

<snip>

 Thanks again to all who helped.
 Brad Loomis
 Los Angeles, CA >>

Hi,
  I see from your post you are setting one of the drives to ID 0 (zero). As
I
recall, ID 0 is reserved for the SCSI controller itself, and is not supposed
to be used for any other device. You might try resetting ID #'s on the
drives, so as not to use ID 0, and see if that helps.

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