[rescue] SE UltraWide cable length question

[Greg A. Woods]

[ On Friday, July 12, 2002 at 18:19:19 (-0500), Scott Newell wrote: ]
> Subject: Re: [rescue] SE UltraWide cable length question
>
> At 07:05 PM 7/12/2002 -0400, Greg A. Woods wrote:
> >The width of the bus makes little or no difference to the maximum
> >length of the bus -- it's the speed (signalling rate) that matters.
> 
> Skew across the bus?

What is "skew"?

On a properly designed cable there's no more cross-talk amongst 16 data
lines than there is amongst 8 data lines.

RTFFAQ!  :-)

	http://www.scsifaq.org/

(and also remember it's the speed of the FASTEST device that determines
the maximum length!)

(and to potentially explicitly answer Josh's implied question, "Ultra",
or Fast20, aka a 20MHz bus, is restricted to 1.5 meters (or maybe 0.75
meters, depending on who you ask) regardless of how wide it is; and
further remember that the distance between stubs must be at least 0.3
meters too -- and anything faster should be running with differential
signalling, either HVD or LVD though you'll probably only ever find LVD
for this speed, and there the max length is up to 12 meters, and no you
can't mix signalling on the same bus so LVD devices are required to
revert to SE mode when another SE devices is on the same bus)

-- 
								Greg A. Woods

+1 416 218-0098;            <g.a.woods at ieee.org>;           <woods at robohack.ca>
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