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A four-head multiterminal.

A multiseat, multi-station or multiterminal configuration is a single computer which supports multiple independent users at the same time. The configuration typically consists of a set of input (e.g. keyboard and mouse) and output (e.g. monitor and headphones) devices for each user.

Contents

Motivation

With the increasing capacity of processors and memory, commodity personal computers can now perform significant numbers of tasks simultaneously without slowing down. However, using standard computer configurations, only one user is able to use the computer at a time, limiting the effectiveness of the system as it remains idle most of the time. With a multiterminal, a lot of users can share the same computer, so more of its total capacity is going to be used. For example, if someone is just using a web browser or word processor, no one else can use the computer and 90% of the system's resources may be idle - but with multiterminals, other people will be able to use the otherwise idle resources. However, if someone is using all of the system's resources (playing an resource-intensive computer game, for example) the other users will have a very slow system.

Multiseats are also more cost-effective: it is not necessary to buy separate motherboards, microprocessors, RAM, hard disks and other components for each user. For example, buying one high speed CPU usually costs less than buying several slower CPUs.

History

In the 1970s, it was very commonplace to connect multiple computer terminals to a single mainframe computer, even graphical terminals.

However, the idea to use the more contemporary X11 interface for supporting multiple users appeared in 2001.[1] It was implemented by a Brazilian named Miguel Freitas, using the Linux operating system and the X11 graphical system (in that age maintained by XFree86).[2] The way that Freitas did was a patch in the X server to execute lot of instances of X at the same time such that each one captures specifics mouse and keyboard events and the graphical content. This method received the name of multiseat or multiterminal.

After Freitas, other solutions appeared in 2003, such Svetoslav Slavtchev, Aivils Stoss and James Simmons worked, with the evdev and Faketty [3][4] approach modifying the kernel Linux and letting more than one user independently use the same machine. In that time, the Linux Console Project [5] also proposed an idea to use multiple independent consoles and then multiple independent keyboards and mice in a project called "Backstreet Ruby".[6] Backstreet Ruby is a kernel patch for the Linux kernel. It is a back port to Linux-2.4 of the Ruby kernel tree. The aim of the Linux Console developers is to enhance and reorganize the input, the console and the framebuffer subsystems in the Linux kernel, so they can work independent from each other and to allow multi-desktop operation. The Backstreet Ruby idea was never finished.

In 2005, the team of C3SL (Center for Scientific Computing and Free Software),[7] from Federal University of Parana in Brazil, created the solution based with nested X servers, such Xnest and Xephyr.[8] With this solution, each nested X server runs in each screen of a host X server (e.g. Xorg) and a modification in the nested servers let it get the exclusivity of each set of mouse and keyboard. In 2008, the C3SL group releases the Multiseat Display Manager (MDM) [9] to ease the process of installation and configuration of a multiseat box. This group, also in 2008, conceived a live-cd [10] for tests purposes.

Multiseat is a planned feature for Fedora 12.[11]

Requirements

Hardware requirements

Each monitor will need to be connected to a graphics output from a video card. For example, to make a four-head (four users), would require four monitors, four keyboards, four mice and two dual or four single output video cards. Keyboards and mice would all need to have USB instead of PS/2 connections, after which, they can all be connected to a USB hub. Additional devices and peripherals could also be assigned to each seat.

Software requirements

GNU/Linux

There are different solutions to set up a multiseat and others are constantly being developed. The X.Org Foundation maintains a wiki page with the latest news concerning the solutions. Currently the most pointed solutions by X.Org's wiki are the solutions using either multiple Xephyr servers over a host Xorg or run severals instances of Xorg.

The MDM tool helps to automatize the process of installation and configuration. Users that want to try multiseat are totally encouraged to try such a tool and avoid the old and hard way to set it up through these howtos (evdev, Xephyr), as stated by foundation's wiki page. On the other hand, MDM suffers from lack of updates and releases beyond the initial announcement ([1] and [2]).

Windows

For Windows 2000, XP and Vista operating systems, there are several commercial products to implement multiseat configurations for two or more seats. Within these products we have ASTER, BeTwin, SoftXpand and Friendly Seats .

Case studies

Paraná Digital project

One of multiterminal's successful cases is happening at Paraná Digital project. It is creating multiterminal laboratories on 2000 public schools of the state of Paraná (Brazil). More than 1.5 million users will benefit from the 40,000 terminals when the project is finished. The laboratories have four-head multiterminals running Debian. The cost of all the hardware is 50% less than the normal price, and there is absolutely no cost with software. This project developer is C3SL (Center for Scientific Computing and Free Software).

Notable installations

See also

References








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