Re: 8500 won't boot if unused drive disconnected
On Fri, Mar 22, 2002 at 12:33:44AM -0500, Michael D. Crawford wrote:
> (Chris Tillman replies that I can't boot because the termination is missing
> when I remove the drive on the internal bus at ID 0).
> That makes the most sense to me. What has me perplexed is that I normally
> boot from an external drive, and the Mac doesn't appear to even try to boot
> unless the drive that holds the terminator on the internal bus is present.
'Cause it can't read from the scsi bus. It doesn't matter if the drive is
turned on, but the bus has to be terminated at both ends. Most external
SCSI drives sold in the last several years have automatic termination
built-in; they sense if they're last on the chain and terminate themselves.
But the assumption is always that the other end of the bus is terminated
(inside scsi 0).
> I found terminators that go on internal 50-pin ribbon cables. I've ordered
> various whacky SCSI stuff from these people before and they're pretty good:
> (scroll down the page to Internal SCSI Terminators, the table marked SCSI 1
> & 2 terminators). There's lots of helpful SCSI information on their pages.
> They have two available, the SCST-5520, and the SCST-5600 which is a
> pass-thru terminator. The first is $17.35 and the pass-thrue is $19.20. I
> ordered the pass-thru. 2-day shipping is $11 to me in Maine.
> Note that my new drive won't go on the existing internal bus (the one with
> the MESH controller, that came built in with the Mac) so I can't use that
> for the termination.
> I just got an Adaptec 29160 today to use for the new
> drive. I also got my first attempt at the new drive, a Quantum Atlas 10k
> III, but it doesn't work and I have to get it replaced :-(.
> (There's two kinds of 29160's for the Mac, the 29160 and the 29160N. The
> "N" has a single-ended SCSI connector externally, the 29160 with no "N"
> has an Ultra160 connector. My Mac comes built in with on old-fashioned
> scsi external connector, and I thought it would be useful to eventually
> connect Ultra160 drives externally, so I got the 29160. As far as I can
> tell, the only difference between the Mac and PC 29160's is the firmware -
> I have seen some mention on the web of someone flashing a PC 39160 (a 2-bus
> adapter) with Mac firmware and having it work).
Out of my league at this point ...
*------v--------- Installing Debian GNU/Linux 3.0 --------v------*
| <http://www.debian.org/releases/woody/installmanual> |
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| Chris Tillman firstname.lastname@example.org |
| May the Source be with you |