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I know that every operating system worth using supports multiple independent users; this makes it easy for several people to share a single computer, with their own documents and everything. However, there is one small problem: the sharing can't occur simultaneously.

Remote Desktop or other similar software allows people to connect to a computer from somewhere else and log-in as any user, without disturbing other users. However I wonder, isn't is possible for multiple people with different user accounts to use a computer at the same time, locally, via multiple monitors and input devices? I tried plugging in a second keyboard, mouse and monitor, however, Windows will mirror or extend the display to the second monitor and the second set of input devices become pretty much like... well... I can't think of anything useless enough to compare them to.

How would I share a single computer with different people? Assume I have a keyboard, mouse and monitor for everyone, connected to multiple video cards (either multiple outputs on a single video card or one monitor/card).

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I'd like to understand why you want to do this. These days it's affordable for most people to purchase a separate complete computer (or laptop). Especially if you're not Linux-savvy and need this to work on Windows. – Torben Gundtofte-Bruun Aug 19 '10 at 12:25
@torbeng, cheaper, less power consumption, less space occupied. – Mircea Chirea Aug 23 '10 at 9:57
There seems to be a good answer here:… – Jamie Kitson Mar 20 '12 at 14:48
up vote 7 down vote accepted

The answer depends on whether you use Windows or Linux:

  1. If it is a Windows computer, nComputing products will do exactly what you want. They supply the keyboard/mouse/video devices, which cost on the order of $75-200 per added user depending on whether you want to add users via PCI (cheapest), USB, or Ethernet. (Windows licensing note: These products will function with or without additional Windows licensing, but you should be aware that Microsoft may not consider an installation legal unless you purchase a Windows Server license for the host and an RDS CAL for each user. Contact nComputing for details.)

  2. If it is a Linux computer, Userful will do exactly what you want. They supply software only, and you connect the keyboards/mice/displays using Linux-compatible commodity hardware.

I am not personally familiar with Userful, but I am personally familiar with nComputing. I was involved in a test deployment as follows:

  • Before: 14 Pentium 4 workstations, each with an IDE drive and between 512MB-1GB of DDR, running Windows XP

  • After: 3 Core 2 Duo workstations, each with a SATA drive and 3GB of DDR2, each workstation shared between 4-6 users via nComputing X-series hardware, still running Windows XP

The difference in performance was phenomenal, and all of the end-users were very happy with the shared workstations. This type of solution certainly wouldn't work well for high-performance computing applications like CAD, GIS, or video editing, but shared computing makes all kinds of sense for office application users, call centers, cybercafes, etc.

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AFAIK this is only possible with Linux (and *nixes) and X11. You can configure multiple Displays which can each use a video device and their own inout devices.

Here's an example of such a setup: Six-headed multiseat system Here are a few additional links for Archlinux and Ubuntu. Or just google around or X11 multiseat. There's even a Wikipedia article about it!

I don't think that such a thing is possible with Windows. On OS X you may have luck and be able to set up multiple X11 heads, but not with the original Apple GUI. But i'm not sure about that.

It works on linux for sure!

[edit] The Wikipedia article reads like multiseat support is not really there yet. IMHO that's just wrong. It works - if you plan it carefully. But there's also a part about solutions for Windows. I haven't checked out any of them, though.

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Why on earth was this answer voted up 5 times? It is 100% wrong. – Ramhound Jun 21 '12 at 16:17
@Ramhound: 100% are just weasel words, just like the amount of votes on this post. Perhaps you could actually explain objectively why the answer is wrong? +1 – Tom Wijsman Jun 25 '12 at 14:37

There are countless solutions along these lines that might do what you want. I wouldn't like to recommend one over another because I think the ROI on something like this is poor, but if you want to start digging away at this that gives you a place to start.

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Your mileage may vary, but my calculations of ROI were actually quite favorable. The up-front cost including proper Windows licensing is only a little bit less than a PC for every desk, but there are plenty of out-year savings on power consumption (huge), antivirus licensing (paid per-host and not per-user), etc. The way I see it, the main deciding factor is whether you're dealing with power users (who may not be happy) or everyday office users (for whom there is no difference). – Miles Erickson Sep 25 '10 at 17:13
Oh this is definitely a YMMV moment, I should have made it clear... I can't make the figures work for me, but I know that doesn't apply to everyone. – RobM Sep 26 '10 at 18:23

I remember reading an article some months/years ago about a hardware device or set of devices which did this for Windows, basically a connection splitter for the keyboard, mouse and monitor so that two people could share the same desktop. This might fall short of your requirements though.

I've tried Googling to find the original article or other information but have unfortunately failed, someone else (with more time on their hands) might be able to find more information.

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That splitter sounds like plugging two devices into a single port, instead of using two or more. – Mircea Chirea Aug 19 '10 at 14:09
Yes, I didn't think it would satisfy your requirements of "many" people but I thought I would mention it. I think I would echo torbengb's comment and ask that you update the question as to why you need to do this, might help you get more focused/useful answers? – Richard Aug 20 '10 at 5:17

Assuming you're talking about Windows, you would do this with Remote Desktop Services, which used to be called Terminal Services. You connect using the RDP client, and not with multiple keyboards, mice, and monitors.

If you are on Linux/Unix, you can just have multiple users SSH into the same machine. Any modern *nix will handle multiple concurrent SSH sessions with no issue.

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-1... the question is very specific about ONLY having additional keyboards / mice / screens for additional users. None of the solutions you mention work without another computer posing as client. – TomTom Sep 25 '10 at 15:39
Furthermore Microsoft does not allow more than one RDP session simultaneously on most non-server versions of Windows. – LawrenceC Mar 20 '12 at 15:01

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