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From: ralph@uhheph.phys.hawaii.edu (Ralph Becker-Szendy)
Newsgroups: comp.periphs.scsi,comp.sys.dec
Subject: 68-pin high-density connector used by DEC: Is it standard ?
Keywords: Connector High-density VAXstation SCSI-2
Message-ID: <11298@uhccux.uhcc.Hawaii.Edu>
Date: 4 Feb 91 22:40:19 GMT
Sender: news@uhccux.uhcc.Hawaii.Edu
Followup-To: comp.periphs.scsi
Organization: U of Hawaii High Energy Physics
Lines: 42

Question 1: On the VAXstation 3100 (and presumably its cousins, VAXserver 
3100, microVAX 3100 and such), DEC uses a 68-pin Honda shielded connector as 
the external SCSI connector (there are two of them in this room, so I am 
certain of that). However, the SCSI-2 standard prescribes the use of a 50-pin 
high-density connector. I hear that Sun 4/3xx server systems have the same 
68-pin connectors (unsubstantiated rumor, haven't seen one muself). Question: 
Is there a particularly good reason for DEC to use a non-standard connector, 
or is it actually some standard I missed ? What is the pin assignment on this 
connector ?

Question 2: On the DECstation 5000 DEC uses a 50-pin connector high-density 
connector (verified, I walked around the one I am writing this on). I hear 
that SPARCstations also use this regular standard-conforming type. Slight 
simmering flame: Isn't it quite silly to stick to the standard on one product,
not on the other ? It also makes life pretty hard on people like me who want 
to move periphereals back and forth, and always need yet another cable. 

Question 3: Internally, the VAXstation 3100 uses something very strange. The 
SCSI controller daughterboard has a 100-pin high density connector which is
exactly the same size as a 50-pin square ribbon cable connector (but with pins
on a 50x100 mil grid). The cable harness consists of a loop of 50-pin ribbon 
cable, both ends of which are seperately terminated in this 100-pin high 
density connector, whereas the connectors for the disk drives are standard 
50-pin connectors (with a 100x100 mil grid), crimped on somewhere in the 
middle of the loop. Question: Why this arrangement with the 100-pin high 
density connector, what is the pin-out on it, where can I buy them (to make 
our own cables, whenever a disk drive gets added to a VAXstation), and why 
does DEC use yet another non-standard connector.

Last question (this one is simple): Where can I buy SCSI terminators for the
high-density 50-pin (Honda-type) connectors ? If possible I would prefer the
new SCSI-2 termination style (110 Ohm to a ~2V low-impedande regulator), but
the old style (220/330 Ohm divider would be OK). Where can one obtain the
50pin (and presunably 68-pin) high0-density shielded connectors in general ?
I know only one manufacturer (Honda), which sells only through smaller 
distributors (I have found a few, none of them stock these connectors though),
not through the big main-line distributors (like Newark, Allied, Hall-Mark).
-- 
Ralph Becker-Szendy                          UHHEPG=24742::RALPH (HEPNet,SPAN)
University of Hawaii                              RALPH@UHHEPG.PHYS.HAWAII.EDU
High Energy Physics Group                                  RALPH@UHHEPG.BITNET
Watanabe Hall #203, 2505 Correa Road, Honolulu, HI 96822         (808)956-2931