If you are
using an electronic KVM, it may be on the
edge of its range, or it could be bad cabling, long
Do these KVM switches fit all the signals (keyboard, mouse, video) onto
fewer wires than you'd expect by packing the keyboard and mouse data into
'unsused' parts of the video signal -- say during the sync pluses?
The trick with a KVM is to keep all the stuff happily in the dark about
being shared, ie everything thinks its always hooked up. The way that works
is the KVM is a smart fast dedicated computer and some dedicated hardware.
Video signals can just be passed straight through with some simple analog
type stuff. Keyboard and mouse have to be fully emulated by the switch,
same for the monitor type sensing stuff.
Older KVM switches were pretty nasty kludges, with the first ones simple
mechanical switches that had lots of glitches.