Multi monitor

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Dual Apple Computer Cinema displays allow for increased desktop space, as well as a wider area of vision.
Dual Apple Computer Cinema displays allow for increased desktop space, as well as a wider area of vision.

Multi-monitor or multi-head are synonymous terms referring to the use of multiple physical display devices such as monitors, televisions and projectors in order to increase the area available for computer programs running on a single computer system.

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[edit] Single PC multi-monitor

Setting up multiple monitors can be an inexpensive way of improving computer usage. It increases the display area, although it is still limited by the size, resolution and number of the monitors. The monitors used for multi-monitor can be different types (LCD or CRT) and sizes. The operating system manages the monitors' resolutions independently.

Video output on a computer is generated by a video card and is interpreted and displayed by a variety of devices. Video cards are typically connected to a monitor (of either the CRT or LCD type), however they are increasingly being connected to projection equipment or television sets. As a result of this trend, manufacturers have produced video cards which can connect to several types of display devices using the appropriate interface. A video card that has two sockets on it (for two monitor cables) is referred to as Dual Head. Two separate video cards are just as acceptable, and so is using the motherboard video socket plus a second video card.

The latest versions of Windows support up to 64 monitors.

Dual monitor support once depended on specialized proprietary video drivers supplied with few video cards, but recently, support for dual monitor configuration comes as a standard feature in Microsoft Windows, Apple Computer's Mac OS X, and on the X Window System.

Initially, the multiple output interface was designed to display the same image on all output interfaces (sometimes referred to as mirroring or cloning). This reflected the fact that these video cards were originally used in presentations where the user typically had his or her face to the audience with a duplicate of the projected image available to the presenter. This concept was further developed by manufacturers and led to the "extended" or "independent displays" mode and the "spanning" or "stretched" display mode. In both these modes, display devices are positioned next to each other in order to create the illusion that the two displays are logically contiguous.

In "extended" mode, additional desktop area is created on additional monitors. Each monitor can use different settings (resolution, color, refresh rate).

Alternately, some video cards are able to "span" the existing desktop area across two monitors rather than create additional desktop space. This is accomplished by using a widescreen resolution such as 2048x768. That is, 2 monitors at 1024x768 resolution each. Each monitor needs to have the same resolution and color depth settings, and often the same refresh rate.

Three main commercial competitors are ATI Technologies with its Hydravision, Matrox with its DualHead Multi-Display and NVIDIA's nView. The technology was once limited to the professional graphics market, but with the advent of more powerful graphic processing units, and the bundling of the software with the respective display cards, penetration into the consumer market has been enabled.

[edit] Multiple PC multi-monitor

Using Xdmx, which is an X Windows proxy, it is possible to have many many more monitors displaying as a single virtual desktop. The LambdaVision display [1] uses 55 LCD monitors which are connected to 32 PCs. This results in a 17600 x 6000 pixel display. As long as the xinerama extension is enabled, GNOME can use the entire desktop.

On Windows PCs, Maxivista and Zonescreen let you setup multiple PC multi-monitor mode through virtual display drivers and client-side software. Multiplicity performs a similar function, though it manipulates the existing client desktops rather than projecting a remote image.

On Macs ScreenRecycler lets you quickly setup multiple PC/Mac multi-monitor mode through virtual display drivers and VNC.

Each of these can also be setup to allow desktop sharing.

[edit] Disadvantages

The primary disadvantage to the usage of dual monitors is that the resources of the video card are effectively halved when the second display device is connected. The decreased processing power and VRAM available to each display may lead to unacceptable performance on both devices. In this case, the second display device may be connected to an additional video adapter installed in the computer allowing the full processing and VRAM capability for each device. However, as newer and more powerful graphics cards are introduced, this problem is not so much of an issue.

[edit] Tools

The multi monitor tools available with the operating system, such as Microsoft Windows can be very limiting. Most of the drivers for video adapters capable of managing multiple monitors enhance the OS's features by their own. Aside from the VGA drivers few third party applications have been created to fill the gaps that the operating systems have not fulfilled. For Windows, Ultramon is a shareware utility that gives you much more control over multi monitor set-ups. ATI provides the free Hydravision software for its cards.

[edit] Graphics cards

The interface of the systems graphics cards governs on what is needed for the setup. Newer graphics cards usually come with 1 DVI port and 1 VGA port or 2 DVI ports. CRT monitors usually utilise the VGA port but higher end CRTs can use the DVI and LCDs depending on the model can support either. Users who have a Graphics Card with 2 DVI ports will need to use a DVI-VGA converter to use a CRT monitor in the setup.

The most common setup for a pair of monitors is side by side (as pictured above) however it isn't uncommon for those who work with graphics to place (sometimes for short periods of time) a monitor above another.

[edit] More than two monitors

Since computers with two or more PCIe interfaces and dual core CPUs are getting more popular, high-end computer users no longer feel limited to two monitors driven by a single main graphics adapter. It is not too uncommon to see users with three or even four monitors connected to a system with multiple graphics adapters. If a dual PCIe interface is not available, a standard PCI graphics card can be used along with a PCIe or AGP card to extend to two or more monitors. Also, some specialized cards support more than two monitors with a single card.

[edit] Multi-display setups in the workplace

In many professions, the use of two or more monitors being driven from one machine is not a new one. While in the past, it has meant multiple graphics adapters and specialized software, it was common for engineers to have at least two, if not more, displays to enhance productivity.[1]

Now that Multi-Monitor setups are more budget-friendly, it is not uncommon to see other professionals use two monitors to quickly view documents side-by-side. This advantage helps push the idea of a paperless office, and is helping to make it more feasible. However, the use of one widescreen monitor also permits viewing of two documents side-by-side.

[edit] Other uses

[edit] Older uses

It was, for a time, a popular configuration for software developers to have a VGA display for the program under development and an independent monochrome Hercules card driving a separate monitor for debugging. The first Macintosh computer to support multiple monitors was the Macintosh II. The Macintosh SE/30, which had one slot in it, also supported a second monitor which could be colour even though the main monitor only supported grey-scale.

[edit] Other Items of interest

  • The Nintendo DS handheld system has two color LCDs placed vertically.
  • The Wacom Cintiq [2] is a drawing tablet/monitor combo, sometimes used alone, but it is often used as a secondary monitor.
  • The PC game Supreme Commander supports Multi-monitors in a dynamic way, effectively displaying two aspects of the game simultaneously.
  • The PC game X2 - The Threat often cited as one of the first video games to utilize a multiple monitor setup.

[edit] References

  1. ^ Bill Gates. April 7, 2006. How I Work. Fortune.

[edit] External Links

[edit] See also

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