Multi monitor
From Wikipedia, the free encyclopedia
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.
Contents |
[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 dual head can be different types (LCD or CRT) and sizes. The operating system manages the monitor’s resolutions independently.
Video output on a computer is generated by a video card and is interpreted and displayed by a variety of devices. Though typically video cards are connected to monitor (of either the CRT or LCD type) 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 device using the appropriate interface.
Dual monitor support once depended on specialized proprietary video drivers supplied with few video cards. However, since that time, 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 reflects the fact that these video cards were originally used in presentations where the user typically has his or her face to the audience and having a duplicate of the projected image available to the presenter is a valuable feature.
This concept was further developed by manufacturers and led to the "exended" or "independent displays" mode and the "spanning" or "streched" 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 only limited to the professional graphics market but with the advent of more powerful graphic processing units, the software comes bundled with the respective display cards and enables penetration of the consumer market.
[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 (http://www.evl.uic.edu/cavern/lambdavision/display.html) 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, on Macs ScreenRecycler,lets you quickly setup multi-monitor mode also.
[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
Additionally, a laptop or tablet pc can be used as an additional monitor, on the PC by using specialized multi monitor software such as MaxiVista, or natively on the Mac.
The multi monitor tools available with the operating system, such as Microsoft Windows can be very limiting. Most of the drivers for video adaptors 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. Some useful features provided by it include better wallpaper management and better window management. ATI provides the free Hydravision software for its cards.
For the Mac there is ScreenRecycler available for using any networked computer as additional display.
[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 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 off of one's main graphics adapter(s). It isn't all too uncommon to see users with three or even four monitors connected to a system with multiple graphics adapters. If dual PCIe interface is not available, a standard PCI graphics card can be used along with an PCIe or AGP card to extend to more than two monitors. Also some Matrox cards support more than two monitors with a single card.
Computer enthusiasts who have the time and money often enjoy creating setups that push the limits of software. Some such power users have created 2 x 4 monitor arrays, that is, two rows of four monitors. While at the moment there are few practical uses for this type of setup outside of immersive simulations, the possible uses are intriguing.
[edit] Multi-display setups in the workplace
In many professions the use of more than two monitors being driven off of one machine is not a new one, while in the past it has meant multiple graphics adapters and specialized software, it was always 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 isn't uncommon to see accountants or lawyers 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.
[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 [1] is a drawing tablet/monitor combo, sometimes used alone, but it is often used as a secondary monitor.
[edit] References
- MaxiVista - software to use an additional networked computer as secondary display Windows
- ScreenRecycler - software to use an additional networked computer as secondary display Mac
