Two Headed Penguins? 50
dmendesf asks: "The
Octane2 workstation from SGI has a neat trick called PowerDuo
that enables a single station to be driven by 2 keyboards, 2
mice and 2 monitors. Is it possible to do the same with Linux and
USB mice, keyboards plus Dual Head videoboards?" How difficult
would it be to develop an X11 solution to do this? Now take this
a step further: could this be done with the secondary machine
a network connection away?
Yes, easily, surely? (Score:5, Insightful)
Of course, you'd need a second sound card for seperate audio, but again that's not too hard.
As for the suggestion that you could do that with X11, well, I laughed when I read that. That's exactly what X and XDMCP is designed for! Have you never heard of X terminals (not xterms)?
When X was developed, the idea was to have lots of thin X terminals and then one big beefy UNIX box to run the applications. Then windows and PCs came along, and they didn't run apps over the network (or at least not until recently).
When I was at college, I had my PC running Linux as a single head, and an NCD X terminal which I'd scrounged from my brother in my room, and in the college's computer room they had some old HP workstation being used as an X terminal. I could easily have 3 people running web browsers, e-mail and news through the one PC (+2 dumb X terminals)
Both of these X terminals were cut-down custom made machines which booted over the network, ran an X server, and broadcasted XDM/CP for any hosts that wanted to offer them a session. It presents a list of machines running XDM, and you simply double click on one, and you get a login screen. Main problem is that both of these "thin terminals" were crap - fixed resolution (at 1280x1024, so usable), but only 8 bit colour depth. Of course, a PC with no hard drive and a decent graphics card would make a better X terminal. NCD still make them - here's a more modern and useful X terminal [ncd.com]
The problem is though, that bandwidth over the network is very much less than you get on a PCI or AGP bus - not enough for comfortably doing very graphics intensive stuff with.(back then, I was using 10Mbit, but there are still problems at 100Mbit). Fine for checking e-mail, reading news, even web browsing, but 2D graphics was painful. 3D graphics would be as well - remember that to use things like the renderer extension, (i.e. any fancy 3D GL stuff, or alpha-blending), requires the application to run on the same host as the video card is in, as the app talks directly to the video card; X is only used for the windowing bit, and for drawing basic stuff like text and buttons.
Really, to do this properly requires compressing the X traffic, like lbx or (plug) Tarantella [tarantella.com], otherwise it's unusable.
Re:Yes, easily, surely? (Score:2)
Re:Yes, easily, surely? (Score:1)
X is extremely flexible in using multiple input and output devices, but because most people have a very straightforward setup, your Linux (?) distribution doesn't bother you with all the posibilities.
Unfortunately my desk is too small, or else I would be running both my 24" and my 20" dual headed
Re:Yes, easily, surely? (Score:2, Informative)
hostname:0.0
Where I put "hostname", is of course the name of hte machine. The next section, after the colon, X calls the "display", and this refers to a complete set of input and output devices for a single user. The last section, after the dot is called a "screen", which is a bitmapped output device for X (basically another monitor.)
Things like VNC and ssh's X forwarding set themselves up as additional displays (screen, keyboard, and mouse combos) and proxy the X events that they receive to the machine at the other end of the network link.
So X itself is designed for multiple users per machine. (think about it, a lot of the original work on X was done at DEC. They had a motivation to support big multiuser machines.) The issue here is whether linux's USB support allows you to read from a single keyboard on the USB bus and ignore key events from other keyboards.
Consider this... (Score:1)
Re:Consider this... (Score:1)
Optimal number of terminals per computer (Score:2)
I agree that cabling and reliability issues would probably make it unoptimal to run all of the displays in a class room from one computer. However, you could still get considerable cost savings by, say, running four or five displays per computer, where those displays were in adjacent carels or clustered together on a table, or even in four cubicles in a commercial environment in a "+" shaped arrangement.
Re:Consider this... (Score:2)
I use an (good) 3 meter cable at home and i see no distortion at all at 1600x1200@100Hz even when the phone rings.
Overly simple solution... VNC (Score:3, Informative)
Re:Overly simple solution... VNC (Score:3, Informative)
The problems here are many. One, your solution uses two computers and just shares some resources - the question was really a means to have one box that acts like two distinct computers. Secondly, for those who don't know nvc is like norton pc anywhere, only it's thinner, cross platform, java client, etc... - so, what you get with it is a server being controled by a client and thus you've turned two computers into
Re:Overly simple solution... VNC (Score:1)
VNC would work perfectly (may be a little slow, however) for having two diffent monitors, keyboards, and mice use the resoures of a single computer over a network connection.
Re:Overly simple solution... VNC (Score:1)
Two Headed Penguins? (Score:1)
What second machine? (Score:1)
Dual Head cards (Score:1, Offtopic)
The main implication of this is that most applications (and X) have no idea they are running on a dual display, they just think I have one huge monitor. For me this means that they throw up dialogs and windows that land accross both displays which is a bit annoying, but in the project the poster mentions I could see problems if X can't recognise each monitor as an entirely separate display device.
--
Andy
Matrox cards work.... (Score:3, Informative)
You could certainly do this with a Matrox G450 dual-head. I did this acidently while trying to setup and dual head linux box to use xinerama :). IIRC the only thing needed was to not specifiy xinerama.
The upshot was I got a machine which proceeded to load up two separate desktops with their own task bars - which you could not drag applications / windows between.
The problem with this was that xdm only ran on one display and on login you got both desktops at once. However, both monitors were acting as an independant display so this kind of thing must possible, maybe just some xdm config tweaking to get this right.
Re:Dual Head cards (Score:2)
But first (Score:2, Interesting)
I don't get what the breakthrough is. Many moons ago I deployed and supported 400 users with 20" color screens and keyboards and mice, with the full office-like suite of applications (with shared licenses) all running off one or the other of two Sun 4/330's runing SunOS (BSD Unix) over 10BaseT. It was called "an X-terminal." It performed so well that users would favor them over PCs.
The coolest thing was getting a shipment of 30 new desktops in the morning and having them all working in front of the users by lunch time. Those were the days...before we got this advanced new easy-to-deploy, easy-to-train stuff like Windows.
I remember reading about this before... (Score:5, Informative)
I believe the following HOW-TO is what you're looking for is here [linuxplanet.com]
http://www.linuxplanet.com/linuxplanet/tutorials /3 100/1/
I've been thinking about doing the same thing myself. With a dual-processor machine, I'm sure I wouldn't notice a change in system performance.Thanks (Score:1)
clarification (Score:5, Informative)
That's not what the question-asker-person was talking about.
The Octane system that was referred to in the question is designed to support two users logged into the machine at the same time, each using a fully functional hardware graphics pipe. From the user's point of view, it's exactly like having your own Octane, complete with V12 ("really fast") graphics.
You can't do that with VNC or an X terminal, because those both involve running your application on the server and displaying its output over the LAN. That's not as fast as working on the local machine, and it doesn't provide you with hardware-accelerated graphics.
A dual-head output from your graphics card also wouldn't be enough, because to implement a system like this you'd have to have two graphics cards, one for each user.
SGI Onyx systems have supported this kind of thing for years; at one point it was marketed as a product called "GroupStation." The way they set it up wasn't particularly exotic, although it may depend on some features unique to the Xsgi X server. For instance, Xsgi has a "-pipe" option that tells it to manage the given graphics pipe; graphics pipes are numbered by the kernel at boot time, so on any multipipe machine you can refer to a specific pipe as 0, 1, 2, or whatever. I don't know if that option is unique to Xsgi or what.
Each user gets a mouse, keyboard, and monitor. The X server on the Onyx would be configured to run one instance of X on each graphics pipe, instead of one instance of X with a screen for each pipe. (In other words,
It should be possible, at least in theory, to do this with XFree86. I know multiple X sessions on one Linux machine are supported; I've done it myself with multiple XDMCP clients running at the same time. If XFree86 supports binding mouse and keyboard devices to X displays, then you should be ready to roll.
The only bad news is that you'd be limited to PCI graphics cards for your 2nd through nth heads, unless you have a motherboard with more than one AGP slot. None of the PCs at my office have more than one, so I'm not even sure whether such a beast exists.
So to sum up, I think this depends more on XFree86 than it does on Linux. If you want to try it, I'd start with the XFree86 documentation to find out if the features you'd require are supported.
Re:clarification (Score:2)
Re:clarification (Score:1)
Re:clarification (Score:2)
Re:clarification (Score:2)
Directly supported by xfree86. You can specify several virtual servers in the xf86config file all of which can have their own mouses, keyboards and monitors.
Just hook up a couple of usb keyboards and mouses to a computer along with a dual-head or two video cards and set them up in the config file.
For sound you'd just have to have two sound cards and configure programs in different servers to use different dsp-devices(which hopefully are not hard coded)..
I don't see the point (Score:2, Interesting)
Sure, the concept is neat, but I don't see how practical this really is. If the person can afford this whiz-bang SGI box, they can probably afford two lesser SGI boxen instead. I don't expect the added space taken by the case to be a major issue, SGIs are usually quite slim.
Maybe... (Score:2, Interesting)
Also maybe the person only needs a second 'computer' occasionally.. or some other strange condition.
(maybe they just want to know for the heck of it)
Although you are correct that it may be more economical to have just multiple boxes.
Re:Maybe... (Score:1)
Re:Maybe... (Score:1)
With two people sharing one box you have one point of failure. With people sharing a server you have aswell a single point of failure. Now just to get your mind thinking, ponder some distributed systems (make lamport logical clocks and other fun things come to mind) and think about n points of failure...
Re:I don't see the point (Score:2)
It worked a treat, it kept costs down, it kept heat and noise down and most users didn't know they were sharing their PC with their co-workers.
The company eventually went full networked Xterms which is a better solution if you have the bandwidth and the server horsepower.
multiple displays (Score:3, Informative)
Just look at an XFree 4 XF86Config file, it's not that big a deal. There's plenty of information about using multiple video cards under XF4 alerady out there, as that capability's been easy to use for a couple of years now.
How bout the same X session and two cursors? (Score:2, Interesting)
Re:How bout the same X session and two cursors? (Score:1)
With many computers, if you connect a secondary pointing device, keyboard and display, you'll have exactly what you're talking about. Haven't tried it with a desktop, but I'd be surprised if it didn't work. I would avoid using identical devices. Just put one user on PS/2 and the other on USB.
Re:How bout the same X session and two cursors? (Score:2)
Not sure linux can do this (Score:1)
Re:Not sure linux can do this (Score:2)
XFree86's VT handling SUX
a quick'n'dirty workaround is described in a link posted in the message (#2936738) above.
Surely if Windows can... (Score:1)
Two Headed Penguins? (Score:1)
Oh you mean two headed computers...
Very possible. (Score:2)
Re:Very possible. (Score:1)
Imagine... (Score:1)