From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Thu,  7 Sep 1995 03:50:52 -0400
From: forsyth@plan9.cs.york.ac.uk forsyth@plan9.cs.york.ac.uk
Subject: Which scsi CDROM can be used?
Topicbox-Message-UUID: 2173a32e-eac8-11e9-9e20-41e7f4b1d025
Message-ID: <19950907075052.JWJPO6oz7JL7pEmEicgkpArFr-1oVbHdEYDf1RqtZtg@z>

>>I tried three kinds of CDROM drives, Sony CDU-561, Chinon CDS-535
>>and Chinon CDS-431.  At the booting Plan 9, while in the CGA mode,
>>it reports us the detected scsi devices, such as

>>   scsi0: cap 415436  sec 512
>>    scsi6: cap 322258  sec 2048

>>in my case.  However, I can get the second line only for CDS-431.

i use a Chinon CDS-535 (SCSI) CDROM on my plan 9 machine at home
and it works very well.  i am using an Ultrastor 14F SCSI controller,
not an Adaptec, but i'd suggest checking the normal SCSI things:
termination, cabling, etc.  i have used the CDS535 as both an internal and
external drive, by the way.  i did have a conflict between an old Seagate ST3283N
SCSI drive and the Chinon: if i looked at so much as a block on the Seagate
with the Chinon on the SCSI bus, the bus and/or adapter hung.  the problem
went away when i replaced the seagate by a newer Quantum drive.
that doesn't necessarily mean that the Seagate was at fault (it might
just have been more sensitive, poor thing, to something the Chinon did).
furthermore, when the same Chinon is connected to an SGI Indy,
the Indy will talk to it, but shows SCSI errors and bus resets when
(i presume) the i/o activity to the SCSI begins to take off; i have the
same problem when an old Sun (Sony) CDROM is connected to the Indy,
doing the same sort of thing (software installation).
again, it could be cabling, termination, or the software in the Sony and Chinon drives.
that's SCSI for you ...

to sum up: the Chinon CDS-535 is not incompatible with Plan 9,
but if it's not recognised, it might indicate a SCSI problem elsewhere.
termination is the easiest thing to check: use Active Terminators,
and check that only the devices at the end of the chain are terminated.
(a machine i looked at recently had terminators in every drive!  note that
in most cases it is not sufficient just to change the jumpers controlling
power to the terminators, you must remove the terminator packs themselves.
failing to do so has been a common mistake round here.)

one other thing that might be important: originally i used the terminator
that came with the Chinon drive.  it seemed to work with Plan 9, but the Indy
put up a terrible fuss, and really didn't want to look at it.
things improved dramatically when i replaced the Chinon pass-through terminator
by a separate Active Terminator.

``well, it worked under DOS and Windows'', someone said to me recently.