Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!ames!oliveb!felix!info-ultrix
From: jg@jumbo.dec.com (Jim Gettys)
Newsgroups: comp.unix.ultrix
Subject: Re: problem following removal of keyboard (VAXstation 2000)
Message-ID: <51457@felix.UUCP>
Date: 29 Jul 88 20:38:53 GMT
References: <50689@felix.UUCP>
Sender: info-ultrix@felix.UUCP
Reply-To: jg@jumbo.dec.com (Jim Gettys)
Organization: DEC Systems Research Center, Palo Alto
Lines: 26
Approved: zemon@felix.UUCP
Reply-Path:

Swapping keyboards while power is still applied is a very bad idea, just
like recabling any part of any computer while power is applied is a bad
idea.

In any case, the bug is that the device driver is not listening for
the power up sequence of the keyboard and setting it to the right mode.
It only does "the right thing" once, and presumes the keyboard will
remember what it is told.

I believe the bug dates back to the days of prototype VAXstation 2/GPX's.
The prototypes, before more protection was added to the line drivers for
production, were liable to blow the keyboard uart in the GPX if you 
swapped keyboards while power was applied.  This highly discouraged 
working on the device driver in this area at the time. (not nice to
damage expensive hardware that isn't yet in production).  By the
time the GPX went into production, additional protection was added to
prevent damage.

I recommend reporting this (antique) bug.

And recabling with power applied is in general asking for trouble.  You
don't know what might short to what while fiddling with a connector.

				Jim Gettys
				Systems Research Center
				Digital Equipment Corporation