That would depend on what kind of KVM it is, does it actually have some electronics inside, or does it just have big mechanical switch that just swaps wires between PCs. Even if it is electronic, does it care what protocol there is on the wires.

That would also depend on the keyboard, because it does not work if it only reads the XT/AT mode switch during powerup (or reset).

Just try, it either works or it doesn't.

probably will, unless it's a strange KVM that electronically echoes commands, and through that some idiot didn't program it to do XT commands, your probably safe.

And through that logic, PS2 has been outdated for so long, that most KVMs will probably be just an electric or mechanical switch.

Attached is a picture of the KVM switch I referred to (apologies for the poor quality - only one I could find that matches the one I have).
It's a D-Link that I bought ages ago, but kept around. This one can be switched via the keyboard or via a button on the switch itself.
The two cables, coming out of the KVM switch, are not removable.

I would veer on the side of caution doing this just because XT Keyboards are hard to get, most KVM were made well after most XT systems left the workforce, and most likely the majority will be just a electronic switching mechanism split between a multiple set of ports anyway. I've read things about frying XT keyboards or the keyboard controller with an XT keyboard - not saying it could happen, but it's something to keep in mind. But then I have switched an AT/XT keyboard to XT before and put it on an AT, all that happened was a lot of beeping.

I also think the older or cheaper the KVM, the less likely it has some kind of "Firmware" detecting anything. The IBM PS/2 standard is not that much different from AT and Serial Mice, at least, not to a level that would require as much alteration as an XT keyboard would to work on a KVM.

creepingnet wrote:

I would veer on the side of caution doing this just because XT Keyboards are hard to get, most KVM were made well after most XT systems left the workforce, and most likely the majority will be just a electronic switching mechanism split between a multiple set of ports anyway. I've read things about frying XT keyboards or the keyboard controller with an XT keyboard - not saying it could happen, but it's something to keep in mind. But then I have switched an AT/XT keyboard to XT before and put it on an AT, all that happened was a lot of beeping.

I also think the older or cheaper the KVM, the less likely it has some kind of "Firmware" detecting anything. The IBM PS/2 standard is not that much different from AT and Serial Mice, at least, not to a level that would require as much alteration as an XT keyboard would to work on a KVM.

Agreed - I am also a bit wary about trying this, since the keyboards and XT motherboards are rare.
The alternative would be to use a standard AT keyboard, build an XT2AT converter and then plug that in directly into the XT motherboard's keyboard connector. That way, any signal coming either directly from an AT keyboard or via the KVM, will be "converted" to XT signals and vice versa.

There's no chance frying anything by using the wrong XT/AT setting, power and ground are still on the same pins. But I'd bet that no modern KVM will work with an XT keyboard. In case I lose my money 😁 please do share the exact KVM model.

DId anyone ever find a solution to this? I am trying to setup a similar arrangement with two Tandy 1000's (SL and TL) using just the Tandy Enhanced Keyboard. I have tried it on a 1998 Cybex Personal Commander II KVM that has DIN5 connectors on the KVM Cable portion that connects to the computers, then a parallel looking cable on the other end that connects to the actual KVM. Coming out of the KVM though is PS/2. Tried it with no luck on either Tandy as neither registers any keyboard input when wired through the KVM. Tried it with the various adapters to (PS/2 to DIN5, DIN5 to PS/2) and it made no difference. The closest I got was hooking up a random PS/2 Keyboard to the KVM. Some of the keys responded, but most gave wrong key inputs or just gave gibberish symbols when pressed.

Also tried it on a two port Belkin KVM that was all PS/2 connectors and used the adapters for the DIN5 needs. Nothing worked that way. I was told the Tandy's keyboard outs are XT compatible, so it does appear that could be the issue and that XT keyboard signals just dont work through the KVMs....