multiseat computer with ubuntu

Multiseat computer with Ubuntu

After having spent many hours working with the goal in mind of

achieving a multiseat (also called multiterminal) computer, I have

decided to write some lines to help anybody interested in building

this kind of system.

The concept of multiseat

A multiseat computer is a particular configuration which allow a

computer to be used for several people simultaneously. There are many

fields of application of such kind of systems: Companies can achieve

big savings on hardware and maintenance while giving service to many

users. The main sites where this can be useful are all those in which

users do not have great graphical requirements, i.e. almost everything

except CPU hungry applications, such as recent 3D games or video

encoding.

The sites which most can benefit from this technique are typically

libraries, schools, public Internet access sites, and in general

almost every site intended for administrative work.

Obviously the underlying operating system is a Linux distribution.

Unfortunately, nowadays there are still too much sites tightly tied to

proprietary operating systems, due to the fact that they must use some

corporate applications developed for exclusive use on such proprietary

operating systems. I hope in a near future that will be just bad

memories belonging to the past, since the main trend in current

developments is based on corporate intranets offering the necessary

tools and software to the employees.

The configuration

I have choosen Ubuntu 6.06LTS as the OS, and a dual head video card to

obtain two seats from a computer.

Why Ubuntu?

Yeah, why Ubuntu?... I have also made myself this question many times

in recent days! I must confess that almost all my previous Linux

experience had been with Fedora Core / RedHat systems (dealing with

them since RedHat 5.x versions). I had only worked previously with

Debian and its derived distributions in just a few ocasions, so

obviously there were some new things to learn.

The reason for choosing Ubuntu is its popularity as a desktop based

distribution. Several governments are choosing or creating Ubuntu or

other Debian based distributions, and the supporting community is

growing quickly. I think it is the distribution in which this kind of

systems can catch most interest.

Why the 6.06LTS version?

A system based on recent software is easier to be reproduced, and will

be more interesting for users willing to reproduce it than an

alternative based on outdated software. Apart from beta versions, this

is the latest Ubuntu version available right now.

The main goal is to give here the necesary steps to reproduce this

configuration. A second goal is to ease the installation as much as

possible. The ideal scenario would be to install only standard

packages, without the need to use patched pieces of code. With the

latest kernel inprovements, and the changes in xorg this is already

possible in some cases.

Why a dual-head video card?

Let's start saying that the use of different cards with one video

output each one would result in

a easier configuration, involving less packages of software. The

reason to use dual head cards is just to adjust to a more realistic

situation. The use of different cards, means either using additional

PCI or PCIe cards.

The first ones (PCI) are almost impossible to obtain in most local

stores (at least in Spain). You will have to buy them in sites such as

eBay or you will have to use old recovered computer parts.

Our particular case was to create a prototype with evaluation

purposes. Depending on the success of the prototype (stability and

users satisfaction) the project can be extended to about 50 computers.

We worked initially with cards coming from dead computers (very old

cards manufactured between 1994 and 1997). That was a total waste of

time: problems with video drivers, available video modes too poor for

today screens, and the impossibility to extend the prototype for a

large number of computers.

The second option is to use a modern motherboard having PCIe slots,

but that means spending money in buying new hardware. In our project,

the plans are intended to use computers whith motherboards having AGP

slots. The only reasonable option for such computers is to plug in

every computer a dual head AGP graphic card.

The last step was choosing the graphic card. We decided to use a card

widely available and supported (i.e. using ATI or nVidia chips) with

dual output, and in the lowest price range. The first prototype was

built using a nVidia 5200 AGP 8x, with VGA output (D-sub), TV output

(unused) and DVI-I output (either analog output using an adaptor or

digital output). This card is well supported and widely available for

about 30 euros (40 USD). For the second prototype, we are using a ATI

9250 AGP 8x.

(Continues on step II ...)

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