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Multiple Users and Multiple Inputs on One Machine? 83

Posted by Cliff from the now-this-is-multi-user dept.
BozoForPresident asks: "Not long after seeing a dual monitor setup for the first time I thought how useful it'd be to plug in another keyboard and mouse for a second user. That $4000 dual headed laptop (reported on Slashdot on Sunday March 16) becomes a more viable purchase when you add a couple of USB keyboards and mice for an additional user. Microsoft will never do it but how difficult would it be to make Linux handle 2 (or more) streams of input and direct them to their respective windows?"
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Multiple Users and Multiple Inputs on One Machine? More

Multiple Users and Multiple Inputs on One Machine?

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  • Congratulations (Score:5, Funny)

    by __past__ ( 542467 ) on Tuesday March 18, 2003 @02:39AM (#5534933)
    You have just invented the serial terminal. Maybe you should apply for a patent.
    • That's the first thing I thought, too.

      How lame is it that a question like this is being asked about a time sharing system like Linux?

      How did something like this get to be an 'ask slashdot' question?

      And why would anybody crowd two people onto one machine in this day and age when most of us have whole networks of multiple machines at our disposal, i.e. single user, multiple machines?

      • You know you're a geek if your home network has two or more computers on it whose only connection is an ethernet cord.
        Unless you are running Power over Ethernet (not likley on a real computers system), this simply means you have some paperweights with a network connection, and no power source.
        (I know what you meant, but as a geek you should apreciate attention to detail.)

      • Re:Congratulations (Score:5, Insightful)

        by tenman ( 247215 ) <slashdot.org@netsuai. c o m> on Tuesday March 18, 2003 @02:54PM (#5538309) Journal
        You haven't been marked at troll yet, so I'll tell you why this is a great ask slashdot post. It boils down to the fact that not everyone knows as much as you, or about what Linux can do for them. It would seem to me that if you could answer this poor guy's question, instead of trying to make yourself sound powerful and mighty, the world just might be a little better place to live. If you don't think what I'm saying is true, then check out the little culture of open Source Developers. And if you don't believe in the Open Source philosophy, then why are you wasting your time with Linux anyway? Why don't you just use some other UNIX? Please stop the high and mighty crap. No body cares that you have more geek'sperince, and the people who might care, can't because your to busy trying to tell them how stupid they are. There was a point in time that you didn't know about serial terminals. There was a point in time where you got introduced to the concept.

        Have a nice day.
        • Just because someone who is clueless asks a question doesn't mean it should make the front page of Slashdot. We could start echoing the Usenet posts to hardware groups asking clueless questions if that were the case.

          Is this gonna turn into a forum for people whining because the connector from their phone doesn't plug into their ethernet jack??

        • You haven't been marked at troll yet, so I'll tell you why this is a great ask slashdot post. It boils down to the fact that not everyone knows as much as you, or about what Linux can do for them. It would seem to me that if you could answer this poor guy's question, instead of trying to make yourself sound powerful and mighty, the world just might be a little better place to live. If you don't think what I'm saying is true, then check out the little culture of open Source Developers. And if you don't belie
        • And if you don't believe in the Open Source philosophy, then why are you wasting your time with Linux anyway?

          Almost modded it as "overrated", as I see your point, but hey - I want to reply this.

          Do you see Linux as your community, guarded by thick-bearded philosophers? Is linux an OpenSource-minded-only-OS? Is no "microsoftian citizen" allowed in your [linuxian] world?

          Otherwise I agree with you. Having funny comments instead of constructive ones brings no more value to people asking slashdot.

          Are these t
      • A good question can come from a "clueless" user.
        Are the answers cluefull?

        why would anybody crowd two people onto one machine in this day and age when most of us have whole networks of multiple machines at our disposal, i.e. single user, multiple machines?
        Single user, no interaction with other users. Might as well use Big Chief tablets or clay tablets.

        In this day, what we want is multiple user, multiple machine, which is a hard (ie many-to-many) problem, hence an interesting problem.

  • The Recipe (Score:3, Funny)

    by zapatero ( 68511 ) on Tuesday March 18, 2003 @02:46AM (#5534954) Journal

    For second serving:

    Add video card. Sift in mouse port and keyboard device (USB recommended when serving more than one). Let blend in x11 conf file. Bind X11. Serve.

    Don't forget audio. Can be nice to have multiple
    audio out as well.

    Hilarity ensues as multiple X desktops compete for such things as CD Drives.

  • It shouldn't be hard at all. (Score:5, Informative)

    by PurpleFloyd ( 149812 ) <`zeno20' `at' `attbi.com'> on Tuesday March 18, 2003 @02:47AM (#5534956) Homepage
    Just get a USB hub, a second video card, a USB keyboard, and a USB mouse. Then run two X sessions, each configured to use one K/V/M configuration. The only issue is if you want to run high-end 3D graphics on both monitors, since you can only fit one AGP card into a PC. You might be able to get around this with one of the Matrox or ATI dual-head boards, but I don't know that for certain.

    Incidentally, you may want to check out this review [dansdata.com] of a product that does something similar in Windows, again using multiple video cards.

    Alternately, you may want to cruise Ebay for some secondhand X terminals. While they tend to be ridiculously expensive new (on the order of a whole new PC), you may be able to find someone with a few they just want to get rid of. Of course, check out the specs before hand and cruise Google to make sure that they'll work under Linux without any special hardware or software. X may be an open protocol, but it never hurts to be sure.

    • The sticky problems are still with the Linux Console code, in that it doesn't really believe in more than one console with keyboard. However, USB keyboards are easier than PS/2 keyboards (easier to not route through the console), and mice are a non-issue (again, do not route through GPM).

      As an alt to an X terminal, try a diskless fanless thin-client box. Motium [motium.com.au] make those with some really special features, but I don't know if the whizz-bang ones are ready for sale yet.
      • How would you hang more than one PS/2 keyboard off one machine anyway? I don't think I've ever seen any system that could do that, which is why I recommended USB (although serial mice would work just as well, now that I think about it).

        Also, it seems to me that you wouldn't really need more than one textmode console, since you can run xterm/rxvt/konsole/gnome-terminal on an X-only KVM head. The only times you really need a real console are during bootup and emergencies, when two people using the system

        • How would you hang more than one PS/2 keyboard off one machine anyway?

          PS/2 is PS/2 is PS/2; you can plug two PS/2 mice or two PS/2 keyboards into a standard machine, diddle with the drivers to tell them about the alternate IO and IRQ addresses and you're away. You cal also get multi-PS/2 port adapters and a lot of the "high-speed serial port" adapters are close enough to 5V RS232 (which is what a PS/2 port is) to work.

          it seems to me that you wouldn't really need more than one textmode console

          That's

          • Re:With USB devices and a recent XFree86, no (Score:1, Interesting)

            by Anonymous Coward
            Are you just making stuff up as you go along?

            PS/2 is most definately NOT 5V RS232. For one things, RS232 doesn't has two data lines, not a single bidirectional one, and no external clock. The bit period is between 60 and 100 microseconds, which means less than 19200 bits per second. I wouldn't call serial "high-speed" until you got well above 10 times that.

        • The only times you really need a real console are during bootup and emergencies, when two people using the system simultaneously wouldn't be a real asset.

          <pointy haired boss>
          Actually, that would be a real asset. My database server crashed down last week, and it took my admin 8 hours to bring it back up. If we could have two admins working on it simultaneously, that'd only be 4 hours.

          Please excuse me now as I have to start dinner. This chicken was supposed to roast for 6 hours, but I'll just turn t
      • A fastish 486 with a decent amount of memory will run as an X client quite happily. It will netboot, and not require a hard disk or CPU fan. Since its power requirements will be pretty low you can probably get away with reducing the speed of the PSU fan too - not much in there to generate heat.
        • True, as long as you don't want to run anything serious locally (like an MP3 decoder or 3D app). Or at a serious res (like 2000x1600x24-or-x32 for a large monitor).
          • Erm, that's not really an X terminal, though, is it?

          • Uhm, on anything faster than a 486, MP3 decoding is not terribly taxing on the CPU. It used to take 100% of my 486DX2/66. (Technically, I was decoding MP2s at the time, but the processing requirements for decode are similar.) Now MP3 decoding takes about 5% of the CPU on my 6-year old Pentium II-300. I can't imagine it taking up more than 1% of a modern machine.

            Perhaps you meant ripping and encoding? Both of those are much more CPU intensive. Or perhaps you mean "Running eye candy visualizations"?

            • It used to take 100% of my 486DX2/66.

              Therefore unusable on even a 486DX4-120, the fastest 486 I know of. If it's sucking 100% CPU locally - make that 50% for a hypothetically faster CPU but IRL probably around 70% - add in the overhead of fetching from the net, try to display something at the same time, and you're a dead duck.

              • If you're running it as a client, it's not actually decoding the mp3 - the server is. So you still don't need much horsepower.

                For a while, I let others log into one of the linux boxes this way, 'cause their boxes were too underpowered to handle both graphics and any real apps.

                • If you're running it as a client, it's not actually decoding the mp3 - the server is.

                  I was speaking of borrowing back horsepower from the client to reduce network load. Playing MP3 or Ogg files locally costs roughly 10x less LAN traffic and is much less laggy. This applies much more so for video or 3D stuff. A 486 is generally not up to decoding MP3s, look toward a Pentium over 100MHz as a working minimum local-Ogg player.

          • if you're using it as a pure X terminal, it's not a problem, because the processing will be done on another machine.
            the 486 will only have to run X, and will be connected to a machine, with a fairly fast connection... like 100mbit ethernet
    • ThinSoft [thinsoftinc.com] also have a product that does it for Windows.

    • Re:It shouldn't be hard at all. (Score:5, Informative)

      by glitchvern ( 468940 ) on Tuesday March 18, 2003 @05:05AM (#5535260) Homepage
      Actually it's harder than this, due to problems in linux with the virtual terminal locking code. You end up having to compile a completely seperate X server with all the virtual terminal code removed. Details here [puc-rio.br]. These guys [sourceforge.net] are working on fixing linux's virtual terminal problems. I think the new virtual terminal code is one of the things not making it into 2.5 which will be put into 2.6 at some later point.
    • The only issue is if you want to run high-end 3D graphics on both monitors, since you can only fit one AGP card into a PC.

      This is partially true, however there are a small number of GeForce4 MX cards available in a PCI version (I use one myself; my desktop system is a strange Athlon server with no available AGP slot). You will not be able to make use of streaming AGP textures, of course, but it's more than sufficient for low- to mid-range OpenGL apps.

    • I've considered this. However I can't figgure out how to make sound work. X11 assumes you have a DISPLAY variable set, and sends data to that, so you can have as many different screens as you wish. (Up to some limit). There is no standard way to do sound in that manor. Many different things are trying, but none are universial, so even if you get something to work, it won't work with much.

      I understand that X11 now has a sound extnetion, which could solve this problem and is standard enough that it is

  • Difficult? You jest, sir! (Score:3, Informative)

    by Pogue Mahone ( 265053 ) on Tuesday March 18, 2003 @02:51AM (#5534966) Homepage
    It's what X is designed to do, right out of the box - provided that your graphics card (and its driver) can configure the 2nd output as a separate display (nvidia can). Just read your XF86Config file one day and see! The only "problem" you might have is allocating the sound channel(s).

    BTW did you know that you can also run multiple virtual X sessions (similar to the virtual terminals but graphical) on the same display/keyboard/mouse? I have 2 sessions running on my machine at home.

  • There is software for windows to do up to 5 (Score:5, Informative)

    by stienman ( 51024 ) <adavis&ubasics,com> on Tuesday March 18, 2003 @02:56AM (#5534982) Homepage Journal
    A company called thinsoft has a product called BeTwin [thinsoftinc.com] which does exactly what you're asking.

    Hook up to four additional USB keyboards and mice, and a monitor for each station (obviously you'd need more video cards if you want more than two stations) and it treats them all as seperate computers.

    I found out about it because MSI bundles a two station version with the geforce 4x00 cards. I haven't tried it, though.

    It works for windows.

    -Adam
  • While I haven't done this with Linux PCs, I have seen it done with some of our SGIs at work. The big Onyx systems can be easily configured (just a few tweaks to the X server setup files) to support mutliple users, each with their own keyboard/mouse and one or more gfx subsystems. It's even easier on the Onyx 300 and 3000 series, as all the keys and mice can be run off one USB channel.

    This can also be done on the Octane, but requires a PS/2 keys/mouse interface PCI card.

    I would suggest looking at the XFree
  • The xfree86 server can do this as-is. When I was trying to setup my dual video card I remember a guy that has posted his xfree86 config for 2 keyboards, 2 mice and 2 monitors.

    You just play with the input and output methods and create two screens.
  • Could someone please clarify why 2 people on one bastard PC would be better than 2 people on two normal PC's with some Cat-5 between them ? Here we actually have two _interactive_ users running amok on the same system, twice as likely to crash something. Or have we invented a PC that can reboot one-half at a time ? This isn't like high-end citrix servers which actually run everything remotely, but those machines usually have a truckload of ram and diskspace. THAT system is suited to concurrent interacti

    • Re:and then ? (Score:2, Funny)

      by Anonymous Coward
      no and then!!!

    • Re:and then ? (Score:5, Interesting)

      by Pathwalker ( 103 ) <hotgrits@yourpants.net> on Tuesday March 18, 2003 @04:03AM (#5535158) Homepage Journal
      Could someone please clarify why 2 people on one bastard PC would be better than 2 people on two normal PC's with some Cat-5 between them

      Software Licensing - or at least that's why I was asked to look into some bizarre korean multihead cards back in 1999.

      At the place I was working at that time, they used some expensive software that was licensed per processor. If one user used the software on a dual cpu machine, 2 licenses would be checked out. If he was on a single CPU machine one license would be checked out. Multiple instances of the software running on the same machine did not check out any additional licenses.

      The idea was, to stick some of these strange cards into a bunch of machines, and put the users who were in training on these boxes. The resule: 2 users per license, saving up some licenses for the people who needed to run the program on the multicpu boxes.

      The cards were completey unsuitable, and burned out quickly, so the project never went anywhere.
    • people keep implying that computers are nice and cheap, so just go buy another one. For some this is not really an option. All those unemployed geeks out there are looking for neat projects that may not cost much. Cheap is relative.

      Also, this just has the interesting factor. Sure you could just plug in another computer but why not try to optimize the hardware that already exists. Many people own a ghz level processor and still only need to surf the web and read email. A setup like this would work fin
      • For the web-surfing email-sending crowd, the world had thousands of old sleeping 300mhz systems just waiting to be powered on. I actually have 4-5 of those junkers lying around waiting for a project to happen upon my sick mind. I keep the multi-ghz PC for my main carnal use.

  • Troll? (Score:2, Troll)

    by vandel405 ( 609163 )
    "Microsoft will never do it but how..."

    Whats up with the ask slashdot trolls as of late... come on!

    Last time i checked Windows already supported -
    Fast User Switching
    Multiple Mice
    Multiple Keyboard
    Multiple Monitors

    Try windows XP for the fast user switching,
    Multiple monitors have been there since win98.
    And just try plugging a USB keyboard/mouse into your laptop and you'll see that the orginals and usb ones work at the same time!

    So it isn't like they're that far from alre

    • ...and no one likes people who don't read the question.

      How exactly are you proposing to bind one keyboard/mouse pair to one monitor using XP? Are you suggesting that different users could be logged in to different displays at the same time?

      • Re:Troll? (Score:1, Redundant)

        by jquirke ( 473496 )
        And no one likes people who don't read the comment.

        He wasn't saying it was possible, but that it was hardly a long way off for Windows NT.
        • Um, even if support is JUST about there, it's not there. Remember - you are dealing with a closed source system. Kinda like being in a jail cell with the keys hanging on the wall outside that you can barely feel with your finger tips. They might as well be on the far side of the room though.

          With open source, you have the power to do whatever you need to do. See this project [puc-rio.br] on multi-user X for an example. It's not pretty, but someone got it to work.

          The original poster was quite correct. MS will Never supp

          • Remember - you are dealing with a closed source system. Kinda like being in a jail cell with the keys hanging on the wall outside that you can barely feel with your finger tips.

            Windows YP, codename: Tantalus [mac.com]

  • Back in early 1999, a couple of jobs ago, I saw a strange device to do this under windows.

    A manager had been somewhere in southeast asia, and had picked up a few sets of a very strange device. They were pci cards that packed a low end video card, and some logic into a single package. Each one had a RJ-45 jack on the back, that connected to a little pod which hooked to a keyboard, monitor, etc to allow a second (third, etc...) user to have their own workspace and desktop on the host machine.

    They only w
  • The way microsoft works, for each person on the computer:

    XP: $300
    Office XP std: $480
    Monitor, KB, mouse: $200
    Cost of HW for extra kb, mouse and monitor?

    Plus the convienance of something freezing for one person and then having more than one person wait on a reboot.
    That is $980. A new PC is $1000. Where are your savings? The $1000 is a new dell with a refurb monitor with XP pro and Office Standard. Plus 256MB of mem.

  • Prior Ask /. on the same topic (Score:5, Informative)

    by Andrew Lockhart ( 4470 ) on Tuesday March 18, 2003 @04:10AM (#5535170) Homepage
    This question was asked quite awhile ago here [slashdot.org].
    There was a tutorial [linuxplanet.com] mentioned in the comments.
  • You can start multiple X Servers, so start another server for the second monitor using a separate XF86config file. In the XF86config file, you configure the input from the other keyboard and mouse. You must start the second X server by hand, because the USB keyboard and mouse won't be connected all time. If it's a PC and mouse/kbd are connected always, you can add the X server startup to the appropriate config file for your xdm. But for a laptop, I would suggest to write a short script to start the X server

  • Was on LKML recently (Score:4, Insightful)

    by ggeens ( 53767 ) <ggeens AT iggyland DOT com> on Tuesday March 18, 2003 @05:28AM (#5535295) Homepage Journal

    This question was asked on the Linux kernel mailing list a while ago. The response was (from memory):

    Yes, you can have 2 keyboards, mice and video cards in a single PC. And you can run 2 instances of X on different virtual consoles. But, there can be only one active VC at any time, and it's hard to change that limit.

    The conclusion was that it would probably be easier and cheaper to set up an X terminal.

  • you can do it on windows already (Score:3, Informative)

    by aderusha ( 32235 ) on Tuesday March 18, 2003 @09:33AM (#5535808) Homepage
    sorry to shoot down the trollish anti-ms nature of this post, but this has been available on microsoft platforms as far back as NT 3.51. the first terminal server/citrix platform utilized this technology (multi video/key/mouse, not terminal sessions over ipx/ip). it's now called "ultra thin client" technology.

    check here [igcinc.com], here [thinsoftinc.com], or here [cyclopstech.com.hk].
  • Back in MSDOS days there were companies that sold you cards that let you run a 2nd, 3rd, and so on user. Each card had a CPU, keyboard connection, video connection. The different users shared the disk drives, printers. Cheap networking was one of the claimed advantages.

    The idea seemed cool to me, at first. But the inconveniences didn't seem to balance the cost-savings.

    And with powerful new computers so cheap now, I think it makes even less sense today. How much did an ethernet card cost back then?

    • There are certain advantages. Firstly, you pay for the cost of an additonal monitor, keyboard, and mouse. You are left with several hundred dollars, which if you wanted could be used to improve the specification of the host PC.

      Now if both users were continually running CPU intensive tasks, then there wouldnt be that much of an advantage. But in many cases such as web surfing, word proccessing, programming, etc, there is a lot of CPU cycles which are simply wasted - CPU usage is NOT constantly at 100%. In a
  • I think what the poster wants to do is be able to use something like the dual-display laptop with two users. The suggestion of thin clients doesn't seem to really answer what the poster wants. That would make for a very useful mobile computer. Instead of each person lugging around a computer, getting their computers connected, and then starting to work, the second person plugs in a keyboard and a mouse and they both can begin working. For projects that require a lot of co-operation, this would be great.

  • Already done (Score:3, Interesting)

    by Yenya ( 12004 ) on Tuesday March 18, 2003 @12:43PM (#5537190) Homepage Journal
    I use this setup for ~1 year now - two VGA cards (one AGP, one PCI), two keyboards (PS2 and USB), two mice (PS2 and USB). You need to patch the XFree86 server. More info here. [puc-rio.br]
  • A while ago my organization had this setting: a bunch of tiny little boxes that are designed to run only X, and have everything run on the power horse servers.

    This centralized computing model saved some HP-UX licenses. It later became obsolete when we started adapting linux.

    anothe roption I would probably look into is Xvnc. (Real VNC [realvnc.com]) Unlike it's Windows counter part, it allows you to set up multiple independent desktops.

    • Yes, and sun has them they are called the Sun Ray. More about them here. They are priced at 525 you add keyboard, video, mouse, and end user ;-) http://store.sun.com/catalog/doc/BrowsePage.jhtml? catid=40767

      I actually got to use them at the benchmarking center and you could not tell they were not running x native (IMHO). Well this is not a Linux solution it is an X / Unix solution and the Sun Ray may even work with a Linux X server. Something to look at at least.

  • Wow, talk about niche markets! (Score:1, Funny)

    by Anonymous Coward
    Aiming at siamese brothers, huh? Smart kiddo!
  • Couldn't a windows user put a full screen VPC session on one monitor, assign a keyboard and mouse to it, and continue working with the host on the other monitor? Shared Folders would allow simultaneous use of the C: drive (or shared networking).

    Haven't tried it, but sounds like its worth a try for the windows side...

  • You are probably best off getting yourself a bunch of low-cost computers like a mini-itx [mini-itx.com] or Walmart PC [walmart.com]. If you are really pressed for cost, you can get a bare mini-ITX motherboard for abour $80 and add an ATX power supply for another $20, and whatever keyboard and mouse you like, and stick it into a cookie tin.

    You can then either boot the machine from an Linux Terminal Server [ltsp.org] floppy or CD, or from something like a Knoppix CD [knoppix.de], or you can netboot them; you don't even have to bother installing anything loca

  • http://pxes.sourceforge.mot.com/

    1 server and N diskless PXE enabled machines. You can do it for about $150 per machine.

  • Latest linux Journal has article on synergy which allows you to use the same mouse and keyboard on multiple machines. I easily scoot my mouse pointer off the screen and the mouse pointer on the other machine moves.now mouse and keyboard events are sent to the second macine. There's no limit to the number of machines you can hook up this way. I have two linux boxes and my laptop all in a row using the same keyboard and mouse. The best part is that each machine's keyboard and mouse still work. So two people

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