Very Computer

I am wondering if it is necessary to terminate the SCSI port at the rear
of the workstations using SCSI terminator. My terminator is very hard to
take off and there are cases I need to use the port. Thanks very much.
--



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Home address:
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Kingston, ON K7K 4G8

were:

Quote:>>>I am wondering if it is necessary to terminate the SCSI port at the rear
>>>of the workstations using SCSI terminator. My terminator is very hard to
>>>take off and there are cases I need to use the port. Thanks very much.
>>>--

IF it is the end of the scsi chain, then most definately YES it
needs to be terminated. The only question that comes to mind is:

does the card have a self termination feature?  Does it autosense
no connection on the connector ans do the termination itself.

The scsi buss is terminated at both ends. This may be at the end
of the internal chain inside the machine or the card itself. The
other end may again be the card (host adapter) or the end of the
external chain.

Overdoing the nummber of terminators is bas also. The are two and
only two terminators per chain.

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In all the documentation I have run across the scsi port on the mother
board or an Sbus card is self terminating if nothing is connected.  It
is only when you start chaining devices from the scsi port that you
need to terminate the last device in the string. (and that is not required
on short chains).

--
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   Yes, you do need that terminator. The SCSI bus is supposed to
be terminated at both ends. However you might still be able to
use your computer if you don't follow the rules. The idea of
the terminator is to keep the pulses running around the SCSI
bus nice and square. The terminators prevent reflections off
the ends of the bus from changing the shape of the signal
pulses and confusing the drives and controllers. If you have
a short SCSI bus, it might work with only one terminator. But
if your disk drive gives you trouble, you woun't know if its
because the drive is going bad or because you aren't following
the SCSI terminator rules.

    Sun computers have different arrangements for termination
inside the box and the hardware instruction booklets avoid trying
to explain complicated technical details like SCSI termination.
Perhaps if you mentioned exactly what computer and type of terminator
you have, someone could give you specific advice.

--

|> I am wondering if it is necessary to terminate the SCSI port at the rear
|> of the workstations using SCSI terminator. My terminator is very hard to
|> take off and there are cases I need to use the port. Thanks very much.
|> --



|> Kingston, Ontario K7L 3N6        Tel: (613) 545-2723 (o)
|> Canada                           Fax: (613) 545-6463
|> Home address:
|> 58 1/2 Chatham St.               Tel: (613) 547-1353 (h)
|> Kingston, ON K7K 4G8

  YES.  

NO.

It is necessary to terminate the SCSI port on the last device on the chain if you
have devices attached to your workstation.

But it is NOT NECESSARY to terminate the SCSI port on the the back of your
machine if you have no devices attached.

Systems Integration and Networking Manager              
Fujitsu-ICL Caribbean           Tel   : (809) 623 2826
46 Park Street, Port of Spain, Trinidad

: |> I am wondering if it is necessary to terminate the SCSI port at the rear
: |> of the workstations using SCSI terminator. My terminator is very hard to
: |> take off and there are cases I need to use the port. Thanks very much.
: |> --

:   YES.  

This is interesting. The only SUN workstation i've seen that
explicitly says that the SCSI port needs terminating is the
SPARC 2000's and SPARC 1000's. SUN doesn't normally ship
terminator with their desktop workstations.

George Nassiopoulos

I agree, BUT with an internal
IBM-DSAS-3540-S47W cyl 3302 alt 2 hd 3 sec 108
I was horriyfied for several days.
IT ONLY WORKED WITH AN EXTERNAL TERMINATOR !!!
(tried every combination with multiple machines!)

Just to warn you

Rainer

--

Rainer Gallersdoerfer

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Quote:>I am wondering if it is necessary to terminate the SCSI port at the rear
>of the workstations using SCSI terminator.

Yes and no.  It is necessary for most of the older SCSI interfaces on the
RS/6000, and it is not necessary for most of the newer SCSI interfaces.

To find out which one you have, I must refer you to the bible of RS/6000
hardware, the "Common Diagnostics and Service Guide", or its sucessor,
"Adapters and Cabling Information".  One of these white books came with
your machine, and you've been keeping it on your bookshelf ever since,
right?  The chapter on SCSI cabling describes when external terminators
are needed and when they aren't.

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