Re: ADB Switchbox requirements

["Bill Garber" <willy4SPAM6pa@comXcast.net>]

"ToasterKing" <toasterking@SPLATbigfoot.com> wrote in message
111020031335239425%toasterking@SPLATbigfoot.com">news:111020031335239425%toasterking@SPLATbigfoot.com...
> In article <20031010064354.15639.00000094@mb-m13.aol.com>, Michael J.
> Mahon <mjmahon@aol.com> wrote:
>
> > The controller protocols are not designed for hot-swapping either.
> > That means that the switched device(s) will not have been properly
> > "introduced" to the controller, and will not, in general, be initialized
> > as the controller would like.  This can result in spurious message
> > delivery and peculiar reactions by the host system.
>
> That does help explain its operation.  As long as the ADB devices were
> present when the system was booted and they have not changed since
> then, I've never had a problem with a system recognizing the devices it
> had already reocgnized at boot.  Thanks for the info.
>
> > >  A standard ADB cable
> > >should work fine.  Hint: If you don't have spares, you can also use an
> > >S-Video cable in place of an ADB cable -- they're identical as far as
> > >connectors and shielding.
> >
> > Well, not quite identical--when you use an S-Video cable for ADB,
> > you put the ADB signalling on one of the internal shields, and +5v
> > on a center conductor.  It works, since ADB is low speed, but
> > it isn't made like an ADB cable.
>
> I stand corrected -- so shielding isn't the same.  If that's the case,
> I can see how the shielding of an S-Video cable wouldn't be as
> effective, since the shield is not carrying signal ground.  That
> doesn't seem to be too much of an issue, though.  Like you said, ADB is
> low-speed and as such isn't as prone to noise or even very short logic
> glitches.  Apple also says the maximum cable length of the ADB bus
> should be 5 meters.  In the past, I've used cabling about 6.1 meters in
> length involving 2 devices plus a switchbox (that's cabling to one
> computer), and 3.7 meters of that was S-Video cabling -- and it still
> always worked fine.  But thanks for the heads-up.

You could always pass a small resistor between signal ground and
shield ground in the switch box rewarding you with that extra amount
of protection.

Bill @ GarberStreet Enterprizez };-)
Web Site - http://garberstreet.netfirms.com
Email - willy4SPAM6pa@comXcast.net
Remove - SPAM and X to contact me



---
This email ain't infected, dude!

Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.525 / Virus Database: 322 - Release Date: 10/9/03