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From: chris@com50.c2s.mn.org (Chris Johnson)
Newsgroups: comp.sys.sun
Subject: Re: Sun SCSI termination ?
Keywords: Hardware
Message-ID: <1990Aug29.231026.9996@rice.edu>
Date: 27 Aug 90 16:51:05 GMT
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In article <1990Aug13.011541.6424@rice.edu> devil%TECHUNIX.BITNET@cunyvm.cuny.edu (Gil Tene) writes:
>
>Hello Netland, this is a SCSI termination question :
>
>I know of two very different ways of terminating SCSI cables; one is with
>terminator plugs, and the other is with device on-board terminators.
>
>- Which Suns don't provide termination power on the SCSI bus ?
>  (Does the Sparcstation 1,1+,SLC,IPC ?)
>
>- If the Sun DOES provide termination power, can setting the terminators
>  on the drive to use the drive's power HURT anything (two power sources) ?

The Sparcstation 1 and 1+ provide termination power throught a socketed
fuse.  By extension, I would guess the SLC and IPC do also, but I haven't
seen the guts of one yet to know for sure.

[Ed's Note: Just for grins, I've been dealing with this problem a little
myself lately, and was informed that the Sun-3 (at least the smaller ones
50,60,80) do not provide term power on the SCSI bus. -bdg]

I would imagine the most drives which allow you to jumper termination
power for drive-mounted terminators (like all Wrens) only drive term-power
into those resistors, and not onto the SCSI bus.  If multiple devices
drive term-power on the SCSI bus, they should have back current protection
diodes.  I don't know if the Sun CPU boards have this, or not, but some
SCSI devices do.

   ...Chris Johnson          chris@c2s.mn.org   ..uunet!bungia!com50!chris
 Com Squared Systems, Inc.   St. Paul, MN USA   +1 612 452 9522