Re: Keyboard, plug and... play?

[Nick Holland <nhollan@home.com>]

It isn't purely an OpenBSD issue, as I have a very cheap switch box
myself, and I have had several different OpenBSD machines attached, and
I haven't had any more problem on the OpenBSD systems.  I suspect that a
lot of us has OpenBSD systems attached to switch boxes.

BUT...  I know what you are talking about.  It seems to be more an issue
of individual computers, the keyboard and, to a degree, the switch than
the OS you are using.  I've noted more problems with computers that use
PS/2 keyboards -- no idea why.  LOTS more trouble with PS/2 mice...that
I have some clue as to why (apparently, the mouse and keyboard share
some circuitry, unlike a serial mouse.  Messing with either will often
cause problems with both.  This is very possibly why I've experienced
more trouble switching PS/2 keyboards -- they are often associated with
PS/2 mice).  

By the way, your analysis that the switch is unplugging the keyboard
from one computer and plugging it into another computer isn't exactly
correct, there is a small but vital difference.  When you unplug a
keyboard from one computer and plug it into another, the keyboard has
several seconds to power-down and ensure a complete reset.  When you use
a switch, sometimes the keyboard doesn't power down completely enough to
reset, and sometimes the power spike messes things up and just "crashes"
the processor on the keyboard.

The solutions: 
1) Different switch box.  Some boxes are more "intelegent" than others. 
Some are just unplugging and plugging, as you indicated.  Others switch
electronically, so the computer never thinks there was a disconnect.  A
really good ($$$) switch box will eliminate the problem.  This is the
best answer, but I'll admit I don't live by it myself.  
2) Don't switch a PS/2 mouse.  Mice are cheap and small.  Put one on
each computer.
3) Try a few different keyboards (YES, I know the keyboard works fine
with the other computer.  Try it anyway!)
4) Try a different computer.  Some are more picky than others.  O.k.,
this one is often a pain.  
5) If you aren't switching the mouse, try leaving a computer out of the
switch.  For example, if you have a four-way switch for three computers
and the OpenBSD box is the only problem, put the OpenBSD box at A, leave
B unused, and the other two computers at C and D.  Often, I have found
pausing at an unused position for a moment before switching to the
trouble machine will resolve the problem.  Sometimes turning the switch
S-l-o-w-l-y will make a difference..sometimes good, sometimes bad.
6) Some cheap boxes have a "Reset" button for the keyboard.  As far as I
can tell, it interupts the power pin to the keyboard.  Very easy to
implement on an existing switch. Try unplugging the keyboard from the
box for a few seconds and plug it back in to see if that clears up the
problem.  If so, the KB power interuption switch is worth trying.
7) Implement a hardware reset button on the keyboard.  You should find
an RC network which resets the keyboard processor (in the keyboard) on
power-up.  A N.O. pushbutton switch across the cap will force a reset on
demand.  Make sure you get the right capacitor, though.  (Getting the
wrong one is..um..bad. 8)

  [does it show my background is in hardware and I've been fiddling with
computers long enough to consider a soldering iron a hacking tool? 8-) ]

IF you find that you can't plug a keyboard back into the computer you
are having trouble with after unplugging it (no switch box), you need
either an expensive switch box or a different computer.  Nothing else
will help you, unfortunately.  It isn't OpenBSD.  (It may be possible to
implement something in software which makes the OS more tollerant to
keyboard switching, like periodic keyboard resets, but OpenBSD DOES work
darned well with keyboard switching.)

Hope this helps!
Nick.


Braun Schweig wrote:
> 
> Hello,
> 
> I've just bought a new machine to learn OpenBSD on - which I've attached to my monitor, keyboard and mouse via a CPU/Computer switchbox.
> 
> When I switch to/from the OpenBSD PC from my Windows PC - the keyboard doesn't work. It works switching to/from Windows - it also switches to/from the BIOS/boot screens - but once OpenBSD boots and I switch (ie. "unplug" the keyboard) it doesn't recognise the keyboard when it's plugged back in.
> 
> So... Does anyone have any ideas at all on how to make OpenBSD recognise the keyboard after unplugging and re-plugging it in? (i386 and PS/2 keyboard)
> 
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