On Mon, 10 Jan 2000, Kristian Harder wrote:

> After a while of running, the 'c' key goes
> mad; the keyboard does recognize when I press that key, but it does not
> realize that I release it again, and so I fill my active window with lots
> of 'c', until I press any other key. This seems to be no hardware problem,
> since it occurs on two machines which never had such problems running
> their previous operating system (Ultrix). No other keys are affected. 

  That sounds like the 'up' transition of the key was missed, and the
autorepeat code kicks in and starts repeating the last key code.  I can't
remember at the moment how the keyboard actually works on the Personal
Decstation - I'd need to refresh my memory again and figure out how that
all works again.

> Ok, even if I could think about trying to live with that 'c' problem,
> after a while of running (several hours or so) things get even worse: Then
> the CTRL key gets reverted somehow, i.e. I get control sequences without
> pressing CTRL, and in order to get simple characters typed, I have to hold
> the CTRL button down all the time. This is rather inconvenient...

  I've seen this once in a great while.  I sometimes manage to clear it
somehow, but sometimes I have to reboot.  I suspect that this is also
caused by missing information from the keyboard.

> Are there any known problems with the keyboard driver for this strange
> Serial Desktop Bus the Personal DECStations are using? Sorry, I browsed
> quite some time through the mailing list archive, but I could not find
> anything helpful there concerning this topic.

  The driver for the Serial Desktop Bus can easily miss data when it can't
respond to the interrupt fast enough.  At one time, I was trying to
utilize DMA for this, but so far it's much less reliable.  Someday I need
to get back to that, but there other other things I have to get done
first.

--
Michael L. Hitch			mhitch@montana.edu
Computer Consultant
Information Technology Center
Montana State University	Bozeman, MT	USA