Radboud Verberne wrote:
>
> >I don't know where on the net to find that, I do know: If you're just
> >using regular 640x480 VGA, all the video signals are about 1 Volt AC or
> >so, so it would be possible to use a bunch of analog switches for
> >switching video, the mouse signals (if you switch those) are either
> >RS-232 or PS/2 & thus slow signals so switching them isn't tough, the
> >toughie is in simulating the keyboard to all machines not currently
> >connected to the keyboard (i.e. if you have the #1 of 6 machines
> >connected & turn on #2 through #6, the circuit must handle bootup
> >keyboard acknowledgement properly for them.)
>
> Well, what about the idee to always connect the keyboard to the booting
> computer?
> If you are working with PC A and you power on computer B there will be a
> 5Volt supply available from computer B. When you receive this 5 volt signal
> disconect the keyboard for 10 seconds orso (NE555 timer) from computer A and
> hook it upo the the booting computer. When the 10 seconds have passed the
> keyboard is switched back to the selected computer.

  It's nice to have the state of the Caps Lock, Num Lock, etc. LEDs kept
current on each "virtual copy" of the keyboard for each computer - doing
what you suggest would result in some confusion here, I suspect <G>
There's a whole complex protocol that goes on "behind the scenes" (I'm
getting to re-start for the 4th time on that as I've had some new
machines I built for embedded work specifically have fits & erase their
HDD's & all my notes.  Drat!)  Getting those stabilized...

> >  Audio can also be switched (commonly forgotten by designers of these
> >boxes, and of remote access (dual station units) - or, they allow you to
> >choose between mouse & audio, exclusively.  Hard to remote play Doom,
> >with sound at remote, and with the choice of silencing the unused
> >machines at the computer bench, then!)
>
> I've used common 4066 switchers to switch audio signals. (I used it in a
> receiver and the bandwith was only 3 Khz)

  Good answer <G>

  Mark, mwillis@nwlink.com