On Fri, 17 May 1996, Ernst du Toit wrote:
 
>> As for the keyboard, I just close my eyes and jam the plug in while the box
>> is on to gain keyboard access - done that a few times now and the
>> motherboard still talks to the keyboard. DO THIS AT YOUR OWN RISK :-)

	I've done this a few times, to move consoles (but not the machines)
around. But I certainly wouldn't recommend it, either.
 
J. Maynard Gelinas wrote:

>	At your own risk is right.  At a place I used to work we had four 
>NetBSD boxes hooked up to one head and one keyboard through a switchbox.  
>One day we switched it to one machine and *POOF!* no keyboard interface on 
>the motherboard.  Lucky we had another MB floating around.  The console 
>was used extensively by NOC personel.  I'd recomend against jamming 
>keyboards in on live computers - hell, after this I'd recomend aginsnt 
>using switchboxes.   

	I had one of these switches before: nothing but a rotary switch 
block and an external power supply for the keyboard. IMHO this is one of the
cheap models.

	The more expensive switchboxes provide constant power to the
devices, and switch all of the data lines completely digitally. Most of
them even provide "dummy" signals on those lines back to all the computers
to respond to "reset" commands as if a real keyboard were there, allowing
a computer to re-boot and initialize all of its "devices" even if the 
switchbox is pointing at another computer. Some switches include those
details for PS/2 mice, serial mice, and VGA monitors, buffering and 
smoothing the VGA signals to the monitor to avoid damaging glitches.

	I've even seen them that allow you to shut the keyboard and mouse
power OFF while you swap them out, while still providing stable signals to
the computers. Then power them back up, and the switchbox re-initializes 
the keyboard and PS/2 mouse again.. transparently to the computers of course.

	I seem to recall, however, the minimum price for such boxes to be
over $1500 ...

Cheers,
Phil
--
Phillip F Knaack               flipk@iastate.edu
Database Programmer, NCREMP    Student Development Group
ISU Extension                  Project Vincent, Iowa State University