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From: krowitz@RICHTER.MIT.EDU (David Krowitz)
Newsgroups: comp.sys.apollo
Subject: DN2500 disk cables
Message-ID: <9008141821.AA31711@richter.mit.edu>
Date: 14 Aug 90 18:21:49 GMT
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Thanks to all those who responded to my question regarding
the power and SCSI cables for the DN2500 disks. The quick
summary is:

For the power cable, the connector's pins are labeled 1-4
(if you look closely, you can see the markings). Pin 1 is
connected to pin 1, pin 2 to pin 2, pin 3 to pin 3, and
pin 4 to pin 4. This corresponds to the second diagram
(the "crossing cable") of my original message. The cable
should be about 12" long in order to have a sufficient
amount of slack.

The SCSI cable is the same as the Mac cable I showed in
my original message. With the ribbon cable laying flat
on the desk (no folds), one of the connectors should have
the key which orients the connector when it is inserted
in the drive/CPU on the top side of the cable, and the
other connector should have the key on the bottom side.
The connectors have a small marking (usually a dot or a
triangular mark) on one edge of the connector shell. If
the connectors are installed so that both connectors have
their orientation marks along the red, or striped, edge
of the ribbon cable, then the connectors will automatically
be oriented corrected. The cable should be about 16" long
to account for the couple of right-angle folds.

The Quantum 170S drive formats out to about 165 MB of space.
It runs *hot*! I don't have a mounting bracket made up
yet, so I've got it lying in the DN2500 with the disk
logic board facing up with the DN2500's cover off. The
disk is quite hot, but the logic board doesn't seem any
warmer than the DN2500's CPU board.

The drive seems to be nice a quick. I did a copy-tree
from a DSP90 to a DN3500 with a 697MB disk (the Maxtor
8760E disk with the WD7000 controller) and also to 
the DN2500 with the Quantum 170S. When the directory
contained large files (say /lib for example). The
Quantum drive was a little faster than the Maxtor 8760.
But when the directory contained many small files
(/sys/ins for example), the Quantum drive was about
1/3 faster than the DN3500's disk. Deleting the 
the directories was also faster with the Quantum
drive by about 20%. If the heat doesn't turn about
to be a problem, this is going to be a nice little
system. Thanks again to those who were able to give
me a hand.


 -- David Krowitz

krowitz@richter.mit.edu   (18.83.0.109)
krowitz%richter.mit.edu@eddie.mit.edu
krowitz%richter.mit.edu@mitvma.bitnet
(in order of decreasing preference)