[5480] in linux-scsi channel archive
Re: Help with SCSI card
daemon@ATHENA.MIT.EDU (Kurt Garloff)
Wed Dec 23 17:16:43 1998
Date: Wed, 23 Dec 1998 21:08:44 +0100
From: Kurt Garloff <garloff@kg1.ping.de>
To: ehegstrom@sonoranscanners.com,
Rasana Atreya <rasana@flowerpot.corp.sgi.com>
Cc: linux-scsi@vger.rutgers.edu
Mail-Followup-To: ehegstrom@sonoranscanners.com,
Rasana Atreya <rasana@flowerpot.corp.sgi.com>,
linux-scsi@vger.rutgers.edu
In-Reply-To: <3681237C.842D79AC@sonoranscanners.com>; from Eric Hegstrom on Wed, Dec 23, 1998 at 10:08:12AM -0700
On Wed, Dec 23, 1998 at 10:08:12AM -0700, Eric Hegstrom wrote:
> 68 to 50 adaptor. The upper data lines don't get terminated in this case
> as in this diagram:
>
> ___________ ___________
> ____ | 68 to | | narrow |
> PC | 68 pin wide | 50 pin | |terminator|
> |----------+----------+-------| adaptor | | as is |
> |----------|-+--------|-+-----|---------|---+-------|inside the|
> | | | | | |_________| | |___ZIP____|
> ___| | | | | |
> __|_|___ __|_|___ ___|______
> | wide | | wide | | narrow |
> | HD | | HD | | (ZIP?) |
> |______| |______| |________|
>
There are 68 to 50 pin adapters with (active) termination of the higher lines.
>
> IMHO the only way to go is to use the adatpor to hang it off the scsi
> and us an external wide terminator as in:
>
> ___________
> ____ | wide |
> PC | 68 pin wide |terminator|
> |----------+----------+--------------+--------------| |
> |----------|-+--------|-+------------|-+------------| |
> | | | | | | | |__________|
> ___| | | | | | |
> __|_|___ __|_|___ __|_|____
> | wide | | wide | | 68 to |
> | HD | | HD | | 50 pin |
> |______| |______| | adaptor|
> |________|
> |
> ____|_____
> | narrow |
> | (ZIP?) |
> | device |
> |________|
This is a bit dangerous, as you created a T-like connection for the ZIP
drive. It might work, if the cable length between the connection to the main
line and the ZIP is very short.
If your 68 to 50 adapter does fancy things such as ground lines, you're lost
in any case.
So, get a good 68 to 50 (i.e. with act. termination) and use the above setup.
I guess the poster wants to use another setup:
-------------------------------------+
PC |
|
+----+ +----+ | +---+ +---+
| HD | | HD | +-----------+ | ? | |ZIP|
| | | | | | +----+ | | | |
+-++-+ +-++-+ | | | 68 | +-+-+ +-+-+
++=========++============= DC390F ========----------+---------+
| Sym53c875 | | 50 |
Terminated! | | +----+ Terminated!
+-----------+
|
|
-------------------------------------+
This will work. If the 68 to 50 is crap, you might still be lucky and have
the 53c875 autodetect this and terminate the high lines for you.
Success!
--
Kurt Garloff <K.Garloff@ping.de> (Dortmund, FRG)
PGP key on http://student.physik.uni-dortmund.de/homepages/garloff
There is something frustrating about the quality and speed of Linux
development. I.e. the quality is too high and the speed is too high, in
other words, I can implement this XXXX feature, but I bet someone else
has already done it and is just about to release his patch to Linus soon...
[From a posting of Tigran Aivazian to linux-kernel, XXXX = disk stat]
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