I'm a little late to answer Marc's question, but here's what I was able to do, in case it helps others who stumble across this later.
In short, I was able to connect a Mac Mini, and 2 other PCs to my Dell 2320 using a 4 port KVM. I used the VGA input on the Dell 2320. If you have a VGA-to-HDMI adapter, you may be able to use the HDMI input. Set the video input to COMPUTER to use the Dell 2320. Set it to VGA (or HDMI is you're using HDMI) to use your external systems. I don't have to disconnect or reconnect the mouse or keyboard to use it with any of the systems.
It seems to take around 10 seconds for the desktop to appear after switching systems. Sometimes the display is messed up, and you have to change the video input to something else, then change it back to the input you want, e.g., COMPUTER, VGA.
Details
- Dell Inspiron One 2320 all-in-one (io2320-4444BK, May 2012).
- Mac Mini (MC239LL/A, Dec 2009)
- Dell E6410 laptop (Aug 2010)
- Gateway 838GM desktop (Intel 915 integrated graphics, ~2006)
- IOGear 4 port KVM + audio (GCS634U)
- Logitech cordless keyboard
- Microsoft wired optical mouse
- external 2.1 speakers
This model Dell 2320 has both VGA in and out ports, as well as an HDMI input port. Other all-in-ones may not have input ports for the display, which, I believe would make it impossible to use a second monitor or use with a KVM.
If you've used a KVM switch before most of the setup is the same. Connect the mouse and keyboard to the KVM switch. Connect the KVM cables to the video, mouse/keyboard/USB and audio connectors on your external systems.
Instead of connecting the KVM video to a monitor, connect it to the Dell 2320 VGA input. The 2320 doesn't come with a VGA cable, so I scavanged an old one from my recently deceased 19" flat panel.
To control the 2320, select a KVM cable and plug in only the USB connector to provide mouse and keyboard input, and the audio connector to the audio output. I didn't connect the KVM cable's VGA connector to the Dell 2320 VGA output.
To use the Dell 2320, make sure your video input selection switch is set to COMPUTER, i.e., your Dell 2320. Make sure your KVM switch is set to your Dell 2320, too, so that you can use your mouse and keyboard.
For the other systems, make sure your video input selection switch is set to VGA. Use your KVM switch to select the system to use.