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Re: hotplug PS2 keyboard



On Sat, Sep 04, 2004 at 07:14:30PM -0700, Paul Johnson wrote:
> Pigeon <jah.pigeon@ukonline.co.uk> writes:
> 
> > Sorry, but I have to disagree. I've booted PS/2 systems without keyboards
> > and plugged them in later, without any problem.
> 
> You have weird hardware, then.  8:o)

Off the top of my head... Intel 440BX, VIA 82CXXX, SiS 746FX all do it
without complaint. The PS/2 interface is so electrically simple that
there's really no reason why hot-plugging it shouldn't work, as long
as the keyboard has a sufficiently long reset delay that it doesn't
come alive before the "cchhcccch" of making the connection has
finished. 

This is not always the case - I've done it with a Dell keyboard where 
apparently the keyboard's own microcontroller crashes due to dirty
power lasting longer than the reset delay, and can be brought back to 
life by unplugging it for a few seconds then plugging it in again
more deftly.

Having said that I guess it would be possible to incorporate the
assumption that the interface wouldn't be hot-plugged into the design
in such a way that it became inescapable. Probably wouldn't happen if
I was designing it but not everybody thinks like me. :-)

-- 
Pigeon

Be kind to pigeons
Get my GPG key here: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x21C61F7F

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