awneil 
As previously noted, I have 2560 x 1080 "extra wide" screen.
I would like to get a KVM[1] so that I can switch it between 2 computers.
KVMs for 1920×1080 HDMI are common, but not so much for the extra width.
So the question is: would a 1920×1080 switch be likely to work with the 2560 width? In the old analogue (VGA) days, you could get away with pushing the specs a bit - but does that work with digital? Would 2560 be just taking it too far anyhow?
[1] KVM = Keyboard / Video / Monitor switch
gchapman 
Is RDP not enough?
RDP - Remote Desktop Protocol
awneil the devices are on the same desk; not looking for remote access.
also not looking to "occupy" one device with accessing the other(s).
they may not all be PCs ...
scdoubleu 
An acquaintance of mine is CTO of this company: https://www.displaylink.com. Their focus is HDMI over USB.
jgmdesign 
I have a possible solution as I ran into this as well. I tried 'pushing' a KVM past its posted limits and it did not work >Video tearing, and warping<.
My solution was to replace my two monitors with high resolution ones that could support the higher H/V specs. They are also dual input screens as well so when I want to use the other computer, I hit the source select on the screens to switch to the other input(s).
For the Mouse/Keyboard I use Logitech Unifying products. Essentially these devices can be inter-paired. On the mouse, or keyboard theres a button that selects receiver 1, 2, or 3. On the computer(s) you install teh unifying software and set the software as 1, 2, or 3. The software then does something to the little bluetooth receiver you plug into the USB port and now you have one keyboard/mouse for up to 3 machines.
Yes, I have to press three buttons to switch between computers. It takes seconds to do, and I am fine with that as I do not have another device on my desk, and the associated headache of wires to manage to go with it.
YMMV.
JIm
awneil I tried 'pushing' a KVM past its posted limits and it did not work >Video tearing, and warping<.
Thanks - I thought that might be the case.
Trouble with this is that you can't just "try it and see".
dual input screens as well so when I want to use the other computer, I hit the source select on the screens to switch to the other input(s).
Yes, that's what I'm doing at the moment.
jgmdesign Try looking into the Logitech Unifying keyboards and mice. Worth every penny.
JIm
jgmdesign Trouble with this is that you can't just "try it and see".
SURE YOU CAN!! Buy a few KVM's off of Amazon and return them if they don't work - LOL
Jim
awneil return them if they don't work
but if they only say they'll work to 1920x1080, I can't really complain that they "don't work" at 2560 x 1080
Or am I just being too honest ... ?
awneil jgmdesign found one: https://www.amazon.co.uk/AIMOS-S...
Look towards teh bottom of the page....1920x1080
JIm
jgmdesign wrote:return them if they don't workbut if they only say they'll work to 1920x1080, I can't really complain that they "don't work" at 2560 x 1080
Or am I just being too honest ... ?
YEs, you are. 
Sometimes the way I see it....Amazon created their policy, and they are more than profitable by that policy. I am adhering to the policy. It DID NOT WORK IN MY APPLICATION. They dont ask questions, I dont add to the answers.
JIm
awneil towards teh bottom of the page....1920x1080
further down, they say 2560x1440
so we shall see - no worries about sending back in this case 
jgmdesign Wow. then you might have a solution you were looking for.
Jim
awneil we shall see tomorrow ...
awneil The unit arrived, and works fine as far as the big display goes.
But as a KVM, it's rubbish!
The normal expected behaviour of a KVM is to allow the "console" (KB, Mouse, & monitor) to be switched between the 2 computers without the computers noticing.
But this thing behaves as if the KB, Mouse, & monitor have all been unplugged from one computer, and then plugged in to the other.
This is useless when using extended desktop - as I do - because everything from the external monitor gets dumped onto the main monitor when the external is unplugged!
I might keep it just for switching the KB & mouse, but use the monitor input selection for switching the screen ...
EDIT
Nice touch: it has a remote button, with lights to show if PC 1 or PC 2 is currently selected
Stupid feature: the PC 1/2 lights on the remote button are the opposite way around to the PC 1/2 lights on the main box!
awneil The normal expected behaviour of a KVM is to allow the "console" (KB, Mouse, & monitor) to be switched between the 2 computers without the computers noticing
Well, that's the way all the previous KVMs I've had - 3 different makes & models - have always worked. But they've all been PS/2 + VGA
this thing behaves as if the KB, Mouse, & monitor have all been unplugged from one computer, and then plugged in to the other
Seems to be common with USB + HDMI switches these days.
I guess this is what they call, "progress" ?
But I found the following after a chat with a very helpful tech support guy at Startech:
Most EDID emulators seem to be two (or more) times the price of the KVM - so I think I'll just stick with switching sources on my monitor!
EDIT
Or maybe the EDID stuff can be done on a microcontroller: https://www.st.com/resource/en/a... ...
Seems to be common with USB + HDMI switches these days.
Been trying to get the old KVM to work with one old computer (VGA) and one new computer (HDMI), so this topic has been informative.
I'll try the video source switch as the monitor has both inputs, but did not know I could use both at the same time (by switching sources). Thanks.
Jim
awneil My HDMI monitor has two HDMI inputs; not sure if it'll work the same on a monitor with one VGA and one HDMI input - but you'll soon find out!
HDMI-to-VGA converters are available (I used them on my first RPi; before I got an HDMI monitor) - so you should be able to adapt the HDMI computer to VGA to work with the old switch ...
And EDID is based on ... I2C :) Presumably the graphics card is the master, and it interrogates the monitor/slave.
awneil Just discovered another stupid feature: the connections from the switch to the 2 PCs are USB C - but it matters which way up you plug the USB C !
jgmdesign 
That's really weird, no logical explanation for this problem comes to my head.
What's weird is the only logical explanation for this comment is your head seems to hold a half basket of bologna 
jgmdesign Ok. On that unnecessary comment
