On Sun, 26 Jul 1998, Ake Hedman wrote:

- SNIP -
> Anyway I have tested a simple mechanical switch for 8 computers
>  controlling five NT servers and two linux machines ) and it worked quite
> fine. The only problem we had was that we needed to switch to the server we
> booted otherwise we lost the mouse on the NT machines. A "feature" that was
> a little annoying after a power failure.....

Hmm, another feature from the same house. I'll remember this. Have you
tried to set the BIOS such that there is NO keyboard ?

Mechanical switches were invented mainly for Novell and Lantastic servers,
and for use by personel in-the-know. They work well for that, too.
Anything else, is troubles...

> Mark Willis suggests using 4051 doing the job and I think that sounds like a
> good idea. The question is if it can handle the video signals or if one must
> use some other means for that.

4051 can't switch any signal above about 40 MHz, can't separate them worth
a damn, and can't drive 50 ohm or 75 ohm lines. Mitsubishi, Philips and
others (including JRC or whatever they are called now) make excellent
video switches, including multiple ones, usually in 8 and 16-18 pin SOIC
cases. Some are available in DIL. Any video switch that carries 100 MHz
bandwidth at 50/75 ohms eats a lot of power and runs hot. The other
option, is a binary relay tree. This is known to work well, but remember
that you are routing digital signals at 100 MHz !

hope this helps,

        Peter