>cruller@unicom.net wrote:
>>
>> 1] stick the new drive in. (does it matter which internal drive is
>> terminated?)

Just a few thoughts I feel I should add here:

SCSI termination and drive position make a difference under MacOS, but it's
possible to have a SCSI chain misconfigured and still have a working system
with tolerably low error rates.  Under NetBSD and MkLinux, I have found the
SCSI chain to be rather less forgiving of hardware problems, possibly due
to the less mature (no criticism intended!) SCSI driver code.

A cheesy ASCII art diagram of the way I understand a SCSI chain should be
connected on a Mac: (ms = mass storage device)

  *----[]------[]------[]------@------[]----*
term   ms      ms      ms    ctrlr    ms   term
         e x t e r n a l       i n t e r n a l

Often the terminator is on the control board of the adjacent drive;
sometimes it's a device attached to the connector of that drive.  Note that
the chain should be terminated at the ends furthest from the controller; if
there are no external drives, no external terminator is required.  One, and
only one terminator should reside on each chain.

In addition, it is considered good practice to place the SCSI devices with
the highest bandwidth closest to the controller.  Hard drives are faster
than CD-ROMs, which are faster than some optical drives, e.g.  This keeps
the cable length short for the fast devices, where it counts.

Hope this simplifies the SCSI voodoo a little.  By the way, I was having
problems booting my IIci with 3 external devices connected (including one
very old Apple/Quantum 80 HD).  Replacing the old drive with one of recent
vintage eliminated the booting problems.  I suspect it was a little too
noisy or possibly flaky to communicate reliably with the rest of the SCSI
devices.

--
| Greg Dunn                       | Every year is getting shorter,    |
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