On top of my desk sits a Windows XP box, and an SUSE Linux server sits below; both are set to 1280 x 1024 resolution. I originally hooked them to the monitor, keyboard, and mouse using the BELKIN F1DK102P. For a while, maybe six months, it worked great. And then one day the mouse started acting flaky and then keyboard stopped responding to key-presses. Unplugging and plugging back in fixed it two or three times, but then the keyboard actually died, which was sad because that keyboard and I had been together for a long time and I was very fond of its clickyness.

Next I tried the IOGEAR GCS62. Despite the mouse and keyboard sockets being too close together to accommodate both the AT/PS2 converter and the PS2/USB mouse converter, this KVM worked pretty well. The only problem was that if I shut down the Windows box, which I like to do as often as possible, the KVM shuts down completely: the Linux box is still running and remotely accessible, but the monitor goes blank and the mouse and keyboard turn off (it specifically shuts down when the video card in the windows box turns off, I believe).

Then I tried this Tripplite 2-port KVM. I like this KVM. It's small and simple, comes with its own cables, and can handle the adapters that find their way onto mouse and keyboard plugs with ease. Unfortunately, it behaves exactly the same way as the IOGEAR did. In fact the only KVM I've tried so far that behaves the way I like is the BELKIN (I mean, aside from that whole failing after six months thing).

I've tried shutting everything down and starting them back up in order, Linux first, Windows first... unless the Windows box is on, the inputs and display are all off, which is frustrating because I like to use the Linux box as my default desktop machine.

So, I'd like to have one set of input devices and be able to turn off the Windows box and still be able to see and use the Linux box. If anyone can share a good way to do this, I'd be very grateful.

I use the Trendnet TK-401R. No trouble at all switching between Linux and Windows.

I used to have a Belkin, but the issue was that I could only switch once -- either I could switch from Linux to Window or vice versa, but I could never switch back. The Trendnet KVM didn't have that same behavior. Good luck with it

Thanks for the suggestion, J.W. I was really hoping this was going to do it, but sadly it did not.

Using the Trendnet TK-401R, I still have keyboard in Linux after Windows shuts down, but no mouse. Also, it worked fine *until* Windows was introduced. In other words, I plugged in the Linux box first and ran it by itself and everything was fine. It wasn't until I turned on Windows and then shut that box down again that the mouse stopped working in Linux. Turning the Windows machine back on returns mouse functionality to the Linux box.

Super frustrating. Clearly, I am cursed or something.

A friend suggested that logging of the PS2 port in Linux is conceivable. Anyone know how to turn that on? Anyone know if that would do me any good? Maybe I should just buy a second mouse?

For the record:

Windows XP
Abit KT7E
AMD Athlon

SUSE 10/KDE
ASRock 939Dual-SATA2
AMD 64-bit

Microsoft Optical Intellimouse USB/PS2
Suntouch K101 keyboard AT/PS2

One trick I used with my KVM that had similar probs with mouse was to switch to full screen console (Ctrl-Alt-F1) and then back to X (Ctrl-Alt-F7). That seemed to reinitialize the mouse driver.

Starview SV411, a 4 port KVM that I use, with client's windows boxes and my linux workstations and server I have never had a problem.

no software install for any functionality.
left control, left control, 1-4 to switch systems.

Starview does have 2 port KVM's configured the same way.

ps2 ports for keyboard and mouse on the switch
svga port for monitor.
included cables have one switch connection, svga style, with two colour coded ps2 connectors and the svga connector on the other end.

Thanks for the suggestions. Wasn't prepared to buy a fifth KVM, so I started looking into other options.

VMware was the first thing I thought of. I may still check that out just because it sounds interesting and it's free http://www.vmware.com/products/player/

A friend suggested an even more novel solution: http://synergy2.sourceforge.net/

Synergy shares mouse and keyboard between as many computers of whatever OS as you might have on your desk. It's typically for computers that have their own monitors. At work I've started using it to operate both my OSX desktop with the little Windows laptop that sits beside it. No more leaning over to screw with that tiny, annoying trac-pad. I now control both computers seamlessly with the same mouse and keyboard.

At home, I run the Synergy server on my Linux box and the client on the XP box. That frees up my concerns for the mouse and keyboard. Using a simple A/B switch for the video that I had lying around, I can easily switch the video.

Unlike the KVMs I tried, the A/B switch doesn't care in the slightest whether either box is on or not, and the Synergy client in XP automatically connects at startup. When the XP box is off, the Synergy server waits quietly for it to return.

My only problem now is that my A/B switch is kind of old and degrades the video signal. So I need a new one of those.

Otherwise, I'm happy to report that my office is now a lot quieter.

Sean

Just a quick question, but are all of the KVM's you tried powered by the pc's themselves, so whithout external power supply?

If that's the case it might be the case that's there's just not enough power to keep both systems going. You're problems might be caused by the tiny bit of standby power coming from the windows box. Some KVM manufactors recognize this problem and add a power port to their products. Since you seem to have quite the collection you might want to check and if it does hook up a universal transformer or something. Most KVM's are 5V.

All have been powered passively. The concept occurred to me vaguely, but I never reconsidered it. Now that you bring it up it sounds plausible. And a power supply should be cheaper than buying a new, high-res A/B switch.

Will report back.

Power supply enables the linux box to remain on even after the Windows box shuts down. So, that's cool.

However, now I have a very greenish screen in Linux (looks fine in Windows), and the scroll wheel on the mouse in Linux no longer works right: only scrolls down regardless of which way the wheel is turned.

Solved one problem, two new ones appeared.

Perhaps computers just hate me?

Not computers, electronics rather in this case, well, as far is I know...

Anyway, the problems you describe might be caused by (you won't be glad to hear this) the power supply. Either it's underpowered or it's sending out it's DC power with a ripple. Try switching it with a model that can deliver more (milli)amps.

I've had some problems with various os's and KVM's as well, from being unresponsive from time to time to whole batches of keys not working. Very helpful when you're just hooking up a server to start ssh and the 'h' key won't work. The problem is universal, and happens on both your cheapass KVM to expensive rack switches, it is all caused by some manufacturers not reading (or just ignoring) the fine print in specifications for a certain standard.

Fascinating. I pirated a power supply of the same volts and amps, and now the scroll wheel works properly. The screen, sadly, is still very greenish.

According to Trendnet, the TK-401R wants a 12V DC, 1A power supply, or a 9V DC, 1A power supply. And the 12V/1A one I bought from Radioshack doesn't work as well as the cheap no-name one I had laying around.

So my question now is how many more milliamps is it safe to add? At what point will I be risking a melt-down?

Thanks.

Green screens (or yellow or blue) are sometimes an indication of a connector that's having a bad contact, causing you to miss a color in the RGB mix. I think you're ok with the power supply if your keyboard and mouse work, since KVM's seldom manipulate the signal coming from the VGA as they do with the ps/2 signals (this is because for vga signals have 2 incoming and 1 outgoing and the other way round for the keyboard and mouse).

Current can be equal or greater than the device wants. Voltage have to be equal that the device wants or else it does not work well or it gets fried (damaged). For any DC power supplies, you have to watch the polarity. I suggest power supplies from Jameco or other electronic stores. When buying switch-mode power supplies, I suggest finding low ripple voltage. For any type of power supply, I suggest voltage regulation is with in 1% or lower.

KVM switches that gets their power from PS/2 connections can be modified to get power from an external sources (AC/DC adapters, DC-DC adapters, batteries), but only if a diode is used. Diodes are one way valves when connected in series with the circuit, so the external power source will not get fried by the PS/2 connectors.

KVM switches are constructed differently. Also mice and keyboards are constructed differently. Buying favorite KVM switch does not always work because it depends on the inputs devices too. Unfortunately, you have to try several input devices that works best for your your KVM switch. Lucky for me, the IOGEAR 4-port PS/2 KVM switch works well with my Hitachi CM771 (monitor), Microsoft Natural (keyboard), and Logitech MX300 (mouse).

OK, switched cables with the XP box, and the green screen went away. Everything looks lovely now. Scroll wheel works. Linux box is running while the XP box is off. I'm guarding my excitement, but it looks like I've finally reached the end of this saga. I think I'll purchase a really nice KVM cable, just to hedge my bet.

Thanks everybody for your help, especially Kater0000.

Sean