On 14 Apr 99, at 17:56, Brian.santos wrote:

>  Yes, you need a data switch. You can buy this at any PC hardware
> store.

  There are three basic problems with this advice:

1.  Monitor connections are not really intended to be plugged and
unplugged while the PC is on.  A KVM switch includes protective
circuitry to allow this.  A "data switch" generally does not.

2.  A couple of the lines in a VGA connection carry information about
the monitor to the VGA card.  If you boot a PC while the monitor is
switched away, the video card may initialize to a mode that the monitor
can't support.  [Admittedly, this is probably only a problem for those
with monochrome VGA monitors, and those are fairly rare.]  KVM switches
generally replicate these signals from the monitor back to all of the
attached PCs.

3.  I have not seen a "data switch" with 15-pin VGA connectors
(probably for reason 1 above...).  I have seen them in 9-pin (you might
be tempted to try to use these with an old MDA or CGA, but they're
really intended for 9-pin ("AT") serial connections), 25-pin
(serial/parallel), and Centronix (printer) configurations.


David G

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