Wren IV (?cabling) Problem
Michael McClary
xanadu!michael at uunet.uu.net
Wed Feb 8 19:24:03 AEST 1989
In article <8901201904.AA00222 at sapir.> anderson at sapir.psy.jhu.edu writes:
>I'm trying without success to attach a CDC Wren IV drive to a 4/110....
>What happens is that when the drive is cabled to the SCSI connector on the
>machine, it won't even spin up, though it does spin up when not attached
>to the 4/110. Letting it spin up and then attaching it to the machine, the
>Sun reports that it can't find any sd device.
If a Wren doesn't spin up, the first thing to check is whether you've got
the terminator plugged in upside down. That'll do it on our Jasmine
boxes. (I think it results from asserting RST.) Also: Be sure you've
got power to your terminator.
We're using Wren IVs (packaged both by Jasmine and Relax) on several suns,
including my IV/110. We use a cable from Monster Cable to go to the
Centronix-style blue-ribbon connector on the Jasmine. On the Relax, we
start with the Monster Cable, then a home-brew Centronix sex-changer, then
an Apple-style Centronix-to-DB25.
Pinouts of the SCSI-standard 50-pin header (typically found on the drive
proper), SCSI-standard 50-pin "Centronix Style" connector, and the DB-50
(?) used by Sun. (I didn't check whether Sun does something strange with
anything but varies/TERMPWR.):
Header Cntrnx DB-50 What's connected
------ ------ ----- ----------------
01 02 01 26 01 34 GROUND / -DB(0)
03 04 02 27 18 02 GROUND / -DB(1)
05 06 03 28 35 19 GROUND / -DB(2)
07 08 04 29 03 36 GROUND / -DB(3)
09 10 05 30 20 04 GROUND / -DB(4)
11 12 06 31 37 21 GROUND / -DB(5)
13 14 07 32 05 38 GROUND / -DB(6)
15 16 08 33 22 06 GROUND / -DB(7)
17 18 09 34 39 23 GROUND / -DB(P)
19 20 10 35 07 40 GROUND / GROUND
21 22 11 36 24 08 GROUND / GROUND
23 24 12 37 41 25 GROUND / GROUND
25 26 13 38 09 42 >varies / TERMPWR
27 28 14 39 26 10 GROUND / GROUND
29 30 15 40 43 27 GROUND / GROUND
31 32 16 41 11 44 GROUND / -ATN
33 34 17 42 28 12 GROUND / GROUND
35 36 18 43 45 29 GROUND / -BSY
37 38 19 44 13 46 GROUND / -ACK
39 40 20 45 30 14 GROUND / -RST
41 42 21 46 47 31 GROUND / -MSG
43 44 22 47 15 48 GROUND / -SEL
45 46 23 48 32 16 GROUND / -C/D
47 48 24 49 49 33 GROUND / -REQ
49 50 25 50 17 50 GROUND / -I/O
Note that (neglecting right-left) the DB-50 is numbered:
1 2 3...
18 19 20...
34 35 36...
the centronix-style is numbered:
1 2 3 4...
26 27 28 29...
and the drive header is numbered:
1 3 5 7...
2 4 6 8...
My Sun-4/110 doesn't provide TERMPWR, and leaves DB-50 pin 42 (= header
pin 26, = "Centronix" pin 38) open. If your drive or terminator is
looking for TERMPWR there, it's out of luck. (Did older Suns ground that?
If so, Yike!)
According to my copy of the SCSI spec, the "varies" pin has TERMPWR on the
Header. (Alan Brunner (sp?) from Jasmine was here a couple days ago, and
I think he said that the Wren leaves that pin open. I haven't tested it
myself.) It is grounded on my Sun IV/110's connector, and the Monster
cable propagates it through to the Centronix connector. The SCSI standard
mandates that the pin be an open circuit on a Centronix-style connector,
but warns that some equipment produced before the standard was promulgated
may ground that pin. Thus, the combination of a Sun IV/110 and a monster
cable violates the SCSI spec, but in a way the spec warns you to expect.
So hook it up this way, check for inverted connectors, no TERMPWR on the
TERMPWR pin at the terminator, TERMPWR on the "varies" pin, and if it
still doesn't work, can I have the drive? B-)
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