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<H1>Re: SCSI Cable</H1>
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<STRONG>From:</STRONG> Rooster (<A HREF="mailto:rooster@seaforn.dircon.co.uk?Subject=Re:%20SCSI%20Cable&In-Reply-To=&lt;Pine.LNX.4.05.10002151230300.23317-100000@seaforn.dircon.co.uk&gt;"><EM>rooster@seaforn.dircon.co.uk</EM></A>)<BR>
<STRONG>Date:</STRONG> Tue Feb 15 2000 - 03:43:23 PST
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On Mon, 14 Feb 2000, Irv Thomae wrote:
<BR>
<P><EM>&gt; On Mon, 14 Feb 2000 07:00:29 -0800, Andrew McHorney wrote:
</EM><BR>
<EM>&gt;
</EM><BR>
<EM>&gt; &gt;Well I can get a simple 4 to 6 scsi foot cable for now. When I get my
</EM><BR>
<EM>&gt; &gt;computer desk setup, the scanner will be located much closer and then I can
</EM><BR>
<EM>&gt; &gt;use a 3 foot cable.
</EM><BR>
<EM>&gt; &gt;
</EM><BR>
<EM>&gt; &gt;The scanner came with an adaptec controller which is ok, but I would rather
</EM><BR>
<EM>&gt; &gt;not waste a slot.
</EM><BR>
<EM>&gt; &gt;
</EM><BR>
<EM>&gt; &gt;Andrew
</EM><BR>
<EM>&gt; &gt;
</EM><BR>
<EM>&gt;
</EM><BR>
<EM>&gt; Although it's certainly true that a decent SCSI controller can accept a wide
</EM><BR>
<EM>&gt; mix of devices insofar as addressing and delivery are concerned, OTOH it's also
</EM><BR>
<EM>&gt; true that slow devices can limit bus speed, effectively bringing all down to
</EM><BR>
<EM>&gt; the &quot;least common denominator&quot;. *That*, IMHO, is a strong argument for using a
</EM><BR>
<EM>&gt; distinct (low-speed, cheap) controller for your scanner. Also, with a lower
</EM><BR>
<EM>&gt; maximum speed, the separate bus will more easily tolerate the 6-foot cable
</EM><BR>
<EM>&gt; length.
</EM><BR>
<EM>&gt; Didn't an el-cheapo controller come with the scanner? If not, check
</EM><BR>
<EM>&gt; misc.forsale.whatever , a likely place to find people with extra hardware they
</EM><BR>
<EM>&gt; don't happen to want....
</EM><BR>
<P><P>This is in fact the real nub of the matter. Mixing slow devices and fast
<BR>
devices on the same bus is really going to cause more problems than it is
<BR>
worth. As far as I know the majority of scsi scanner don't allow the
<BR>
DISCONNET command for suspending data transfers while other devices access
<BR>
the bus. That coupled with the higher tolerances you'll need for a 6ft
<BR>
long termination (ie completely active and all devices supplying power, if
<BR>
they can) then it really becomes a headache.
<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;I am sure there are plenty of SCSI gurus out there who can explain
<BR>
to you the limitations of bandwidth between fast busses and slow &amp; fast
<BR>
devices. Personally I have gone the whole hog and use a 4 channel
<BR>
(APB3980UA) controller and seperate out HD's , TAPE/DAT's, CDROM/CDRW's
<BR>
and the
<BR>
scanners (I have 2) onto seperate channels grouping the slowest together
<BR>
and the fastest to make the maximum use of the available bandwidth. Oh
<BR>
incidentally before I got this controiller I had the trusty ol' 1542CP and
<BR>
a APB960 working together. It ran like a dream :)
<BR>
<P>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Hope this helps, you never know it might even work out cheaper
<BR>
than an exotic 68-&gt;25 cable ;)
<BR>
<P><P>Rooster - A friend.
<BR>
<P>&quot;Anyone's friend in particular or just generally well disposed to people?&quot;
<BR>
<P>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;HHGTTG.
<BR>
<P>CUT - Campaign for Unmetered Telecomunications:
<BR>
Bring the best to all affordably. <A HREF="http://www.unmetered.org.uk">http://www.unmetered.org.uk</A>
<BR>
<P><P><PRE>
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