Re: ADB Switchbox requirements

[mjmahon@aol.com (Michael J. Mahon)]

ToasterKing wrote:

<snip>

>Apple recommends not switching ADB cables while the system is
>powered on, but I and many other people have been doing this for years
>upon years with no problem.  Apple has to recommend against doing it,
>though, since it wasn't particularly designed for hot-swapping.  It
>could produce unusual results, or a static discharge could potentially
>fry the ADB controller or peripherals.  As long as you have a good
>ground though, there shouldn't be a problem.  Again, with genuine Apple
>hardware, I've always seen it work.  Heed the advice Bill provided
>about the mandatory "dead spot" in the switch, which any
>professionally-assembled ADB switch should have.

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.

>  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.

-michael

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