Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Two computers, one monitor, zero fiddling (2025)

alexplescan.com

Post reply on HN
Print view View original

111–120 of 153 posts

Re: Two computers, one monitor, zero fiddling (2025)

#111

Post by tim-- »

heatmiser wrote: post #56

I solved the multi-computer-to-multi-monitor problem with a Level1Techs KVM[1]. The price (~$500 for the variant I purchased) initially gave me pause, but the longer I've had it, the happier I am with my decision. It handles all the switching at the hardware level and thus has no perceptible lag for video or anything else. I'm able to connect a single set of peripherals, in my case, two monitors, a keyboard, a trackb…

I went down a similar rabbit hole a while back and ended up building something that attacks the same problem from the opposite direction: instead of just a hardware box that switches everything (video + USB), I wrote Fence[1], a software layer that automates switching USB input devices when you glide the mouse to the edge of the screen.

The idea is basically "Synergy's convenience, but with real hardware switching." You run a tiny client on each machine. When your cursor hits the left edge of your desktop, Fence tells a USB and HDMI Switch to physically redirect your keyboard and mouse to the next PC.

The switching happens in hardware and you can design your layout per-direction and per-device.

Where the L1T KVM is the "one box handles video and IO beautifully" approach, Fence is more of an "IO routing layer" that lets you keep your existing monitors and their auto-input-switching (or a separate video path).

I built it specifically to be cross-platform. You don't pass clicks/keystrokes over the network, just a "switch to pc2 PC, left edge" message.

Not a replacement for the L1T if you want one-button video+peripheral switching, but if someone likes their monitor's own input handling and just wants the "mouse to edge" workflow it's a nice middle ground.

I like the fact that moving the mouse to different edges of the screen can show exactly the source to the sink that I want.

I originally built it for live streaming with OBS, but now, I miss it when I have more than one computer I need to deal with at a time.

[1] https://github.com/timgws/kvm-switch

Re: Two computers, one monitor, zero fiddling (2025)

#112

Post by tim-- »

seany wrote: post #93
heatmiser wrote: post #56

I solved the multi-computer-to-multi-monitor problem with a Level1Techs KVM[1]. The price (~$500 for the variant I purchased) initially gave me pause, but the longer I've had it, the happier I am with my decision. It handles all the switching at the hardware level and thus has no perceptible lag for video or anything else. I'm able to connect a single set of peripherals, in my case, two monitors, a keyboard, a trackb…

I really wish some one made one of these as a DP 1.4 _matrix_ instead of a true KVM. 8in 8 out would be amazing

These exist, but are exceptionally niche, and very, extremely expensive.

Re: Two computers, one monitor, zero fiddling (2025)

#113

Post by onceler »

Yondle wrote: post #110

Thank you! I hadn't thought of using software to handle monitor switching.. I have a very similar setup but my monitor doesn't support usb upstream so I have a dumb usb hub with a button to switch sources then still have to manually use monitor input change. You gave me the idea to setup scripts on the windows / macos system to 'react' to hub detach events (which I click the button) and execute cli commands to change…

This is the setup I (used to) use. My monitor doesn't do usb switching, so I got a cheap ($15ish?) usb switch (one downstream port (connected to a hub), two upstream ports, and a button to switch between them), and run a script on my desktop to send ddc commands to the monitor to switch inputs when it receives usb attach/detach notifications. No keyboard shortcuts, but one button next to my keyboard switches everything.

: I've since replaced the monitor, and found that the new one doesn't support input switching via ddc, at all. But it does switch if only one input is active, and I rarely use both computers at once, so I cope.

Re: Two computers, one monitor, zero fiddling (2025)

#115

Post by vogelke »

m463 wrote: post #105
heatmiser wrote: post #56

I solved the multi-computer-to-multi-monitor problem with a Level1Techs KVM[1]. The price (~$500 for the variant I purchased) initially gave me pause, but the longer I've had it, the happier I am with my decision. It handles all the switching at the hardware level and thus has no perceptible lag for video or anything else. I'm able to connect a single set of peripherals, in my case, two monitors, a keyboard, a trackb…

kvm usb switching is always broken, sometimes subtly, sometimes obvious I use mechanical USB switches to individually switch USB lines like this: https://www.amazon.com/dp/B01I0Y3GEE one for keyboard, one for mouse Problems it avoids - cable speed usb - no extra latency - using boot-up hold-key-down sequences on macos works fine - keyboard doesn't get hung in weird states - no hotkey conflicts - no mouse gets in weir…

I have a Dell 2208 monitor with 4 USB-2 ports. If I bought three of these switches, would I be able to share keyboard/mouse/monitor between two machines? My monitor does not have HDMI, just VGA.

Re: Two computers, one monitor, zero fiddling (2025)

#117

Post by thangalin »

For a run-down of various hardware KVM solutions that can handle high-resolution video at high refresh rates, see:

https://hardwarerecs.stackexchange.com/q/18561/7591

The UGREEN 8K Displayport KVM Switch has been running flawlessly for four months of continuous use.

https://www.amazon.ca/gp/product/B0CFFFHFJT

Re: Two computers, one monitor, zero fiddling (2025)

#119

Post by fiddyschmitt »

Yondle wrote: post #110

Thank you! I hadn't thought of using software to handle monitor switching.. I have a very similar setup but my monitor doesn't support usb upstream so I have a dumb usb hub with a button to switch sources then still have to manually use monitor input change. You gave me the idea to setup scripts on the windows / macos system to 'react' to hub detach events (which I click the button) and execute cli commands to change…

:) yes. For Windows, that's exactly what SimpleKVM does

https://github.com/fiddyschmitt/SimpleKVM

Re: Two computers, one monitor, zero fiddling (2025)

#120

Post by m463 »

vogelke wrote: post #115
m463 wrote: post #105

Earlier quoted context omitted.

kvm usb switching is always broken, sometimes subtly, sometimes obvious I use mechanical USB switches to individually switch USB lines like this: https://www.amazon.com/dp/B01I0Y3GEE one for keyboard, one for mouse Problems it avoids - cable speed usb - no extra latency - using boot-up hold-key-down sequences on macos works fine - keyboard doesn't get hung in weird states - no hotkey conflicts - no mouse gets in weir…

I have a Dell 2208 monitor with 4 USB-2 ports. If I bought three of these switches, would I be able to share keyboard/mouse/monitor between two machines? My monitor does not have HDMI, just VGA.

I bought two 4x1 switches and stacked them on top of each other.

One was connected to my keyboard and (up to) 4 machines.

The other was connected to my mouse and (up to) 4 machines.

for each machine, I need 2 cables from 2 usb ports on the machine to the switches (one for keyboard, one for mouse)

there no multiplexing, there is no hub, there is just a dedicated cable for each device. It works well though it is a little clunky to throw the mechanical switches.

I don't use the usb ports on the monitor.

Post reply on HN