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From: krowitz%richter@UMIX.CC.UMICH.EDU (David Krowitz)
Newsgroups: comp.sys.apollo
Subject: Re:  3rd Party SCSI Disk
Message-ID: <9001171531.AA06409@richter.mit.edu>
Date: 17 Jan 90 15:31:24 GMT
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We have attached a Sony magneto-optical disk drive (an erasable optical
disk with removable 600MB cartridges) which we purchased from Workstation
Solutions. The drive uses the native SCSI disk controller software which
is built into the DN2500 kernal. The cable caused us some problems. The
drive has a standard 50-pin edge connector with the wire clips (like you
see on an external disk for the Mac), but Apollo for some reason decided
to use a 50-pin edge connector with thumb screws to hold the cable in
place. A regular SCSI cable will work, but the connection will not be
real secure on the DN2500 end. Our original cable was an 8-foot (2.5 meter)
one made with regular twisted pair wire, and we had reliability problems
with it. Workstation Solutions shipped us a shorter 3-foot (1 meter) 
ribbon cable which has worked just fine. It seems like the DN2500's SCSI
interface may be a little weak on handling longer cables. One we had the
drive attached, we ran the DN2500 self-test (type "TE" to the memonic
debugger) which checks the SCSI bus and reports which devices are attached.
We then gave the reset command ("RE" to the memonic debugger), and then
the command "DI SD2:0" to tell the system that we had a SCSI device with
a unit number of 2 attached to the system. Finally, we did another reset,
a "DI N" to tell the system to boot off of the network, and a "BOOT"
command to bring the machine up. Once the DN2500 was up, we could run
the online versions of invol and salvol to init the disk by refering
to the disk as "w2:0" for the device. The drive acts like a normal Apollo
disk. The only tricky part is giving the "DI SD" command before booting
(even if you're not booting off of the disk and have to give another "DI"
command afterwards to set the correct boot device).


 -- David Krowitz

krowitz@richter.mit.edu   (18.83.0.109)
krowitz%richter.mit.edu@eddie.mit.edu
krowitz%richter.mit.edu@mitvma.bitnet
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