Extio Technology Guide

Introducing Matrox Extio

With Extio™ remote graphics units, Matrox has introduced a new design layout for computer systems and opened up many new possibilities. Now, the user-interface components of the computer can be separated from the rest of the computer by hundreds of meters of fiber-optic cable. The rest of the computer, typically the most sensitive parts, can be kept in a separate, safe, secure room.

The user-interface components of a system using Extio include, but are not limited to, the keyboard, monitors, mouse, and audio peripherals. In fact, up to 6 USB (Universal Serial Bus) peripherals of any kind can be connected to the Matrox remote graphics unit (RGU). A wide variety of other USB-based input/output peripherals can also be used, including printers and touch-screen controllers. The "Extio" name itself was inspired by "External Input/Output".

Extio was explicitly designed with mission-critical environments in mind. In addition to its remote capabilities and versatile device support, Extio supports multiple simultaneous displays and uses passive (fanless) cooling. The graphics quality, capabilities, and performance of Extio are comparable to having a Matrox multi-display graphics card directly installed in the computer. While there are other extension technologies, Matrox remote graphics technology provides the best combination of integration, reliability, image quality, and distance.

Multi-display support is important when large amounts of information need to be processed, for example, in security monitoring and process control. In such environments, using more than one display at a time is often the norm. By helping to manage large amounts of information, Matrox multi-display support can improve productivity and reduce errors. Various studies report productivity gains between 10 to 50% from using multiple displays. Productivity is improved by reducing the amount of time spent moving information that doesn't otherwise fit on-screen. Errors are reduced by making it more likely that important information is on-screen. Matrox is an industry leader in multi-display technology.

Offering even more flexibility, Extio supports both digital and analog displays. This allows Extio to be used with a wide variety of display technologies. Extio users also benefit from the renowned image quality of Matrox graphics hardware.

Cool parts

Because there are no moving parts, the passive cooling of the Extio unit provides a longer MTBF (Mean Time Before Failure). The wear that even small amounts of friction can cause over time makes mechanical parts more likely to fail than electronic parts. A longer MTBF is very important in mission-critical environments where any down-time can represent great losses.

To minimize down-time, administrators often design redundancy into systems. The capability of Matrox remote technology to separate the user interface from the rest of the computer makes it easier to design redundancy into a system. For example, if a computer connected to an Extio unit fails, the unit can be plugged into another waiting computer with a fiber-optic interface card. The user doesn't need to move to another station. For this reason, the fiber-optic interface cards for Extio are sold separately from the units themselves.

An added advantage for system administrators is that Extio makes it easier to have a separate upgrade path for user-interface components and the rest of the computer. Long Matrox product life-cycles make it even more feasible to upgrade the rest of the computer while maintaining the Extio hardware. An administrator can, with minimal disruption to the user station, upgrade the computer chassis to take advantage of the latest CPU and motherboard technology.

This scenario also shows how IT professionals can maintain systems in a separate room from the unit station. To do this, another set of keyboards, monitors, and mice can be connected directly to the computers in the separate room. Matrox remote technology allows the administration of the systems to more effectively be separated from the use of the system. This can decrease the total cost of ownership (TCO) by making systems easier to maintain and by reducing down time.

Passive cooling has another advantage in that it generates no noise. This is complimented by the capability to place a potentially noisy computer away from the work environment. Minimizing noise is important in areas like dispatch centers where calls need to be heard as clearly as possible, or in audio studios where the advantages of minimizing noise are even more obvious. The small size of the Extio unit and the ability to move the rest of the computer to another room also saves space in the work area. This is an important consideration in space-constrained environments like control rooms.

Expressly designed

Part of what makes Matrox remote graphics technology possible is PCIe (PCI Express). PCIe (not to be confused with PCI-X) is a recent standard for connecting devices to computers. It's software-compatible with PCI but has more flexibility than PCI or AGP. The PCI and PCIe standards are maintained by the PCI-SIG (PCI Special Interest Group), a consortium of over 900 companies. For wider compatibility and because the two standards share a common foundation, most new computers support PCIe in addition to PCI.

A connection between a PCIe device and the system is known as a "link" and this link is built around a dedicated, bidirectional, serial (1-bit), point-to-point connection known as a "lane". A link can use more than one lane at a time but all links compliant with the PCIe specification must minimally support single-lane connections, referred to as "x1" (pronounced "by-one") links. For better compatibility and easier transmission, Matrox Extio uses a x1 link.

The internal architecture of PCIe is much like a local area network in that each link goes to a central hub in the computer that performs network-like switching. This is in contrast to the PCI architecture, where all devices share the same unidirectional, parallel bus. Because PCIe isn't based on parallel connections that can be hindered by timing issues, PCIe allows data to be more easily and cost-effectively transmitted over longer distances.

To connect a Matrox remote graphics unit to a computer, an interface card is installed in an expansion slot in the computer. Even though the transmission protocol used by Matrox remote technology is PCIe-based, Matrox makes interface cards for both PCIe and PCI expansion slots. In the case of PCI, a bridge chip simply converts PCI data to and from PCIe data.

Go the distance

The interface card installed in the computer converts outgoing bus data to an optical signal and converts incoming bus data back to an electrical signal. The card transmits and receives this optical data to and from the remote graphics unit via fiber-optic cable. The unit also converts incoming data to electrical signals and outgoing data to optical signals. The remote graphics unit has integrated graphics, audio, and USB hardware that process the bus data as if it were part of an add-in card directly installed in a computer expansion slot.

Extio connection topology

The conversions to-and-from optical and electrical signals are transparent to the rest of the computer and to the software – no special software drivers are required for this. Further, because the data conversion is an all-digital process, no data is lost or altered in the process.

What also makes Matrox remote graphics technology possible is the fact that raw bus data is transmitted instead of monitor signal data (that is, instead of what's transmitted over a standard monitor cable). This isn't the case with other extension technologies like cable and KVM (Keyboard, Video, Mouse) extenders. The bandwidth requirements for most bus data are much lower than for the resulting monitor signal data.

Bus data contains concise commands and instructions for hardware devices whereas monitor signal data contains a map of every pixel to be drawn on-screen at every cycle. The processing of bus data is done by graphics, audio, and USB hardware in the Extio unit itself. This is where most of the "heavy lifting" of this bus data is done. For graphics, Extio takes advantage of a Matrox-designed graphics chip and large amounts of local graphics memory to process and buffer screen images.

To give an idea of the difference in bandwidth requirement between bus data and monitor signal data, the bus bandwidth Extio uses is under 250 MB/sec (megabytes per second) for all the devices it supports (monitors, audio, and USB). By contrast, the bandwidth required for 4 monitors each using 1920 x 1200* resolutions, 24-bits/pixel, 60 cycles/second is over 1,318 MB per second, and that doesn't include the bandwidth required for the other peripherals (audio and USB data). The savings in bandwidth is greater than what can be obtained through

lossless compression (that is, compression where no data is lost).

See the light

The fiber-optic cable Extio uses is a standard duplex multi-mode cable available from various resellers. "Duplex" means that the cable is actually contains two independent fiber-optic strands – one to bring data to the remote graphics unit and one to bring data back from the unit. "Multi-mode" fiber is usually used for shorter distances (for example, within buildings) as opposed to single-mode fiber which is used for longer distances. Compared to single-mode fiber, multi-mode fiber also has a larger center core, can carry more data over shorter distances, and the equipment to support this type of fiber is less expensive.

Fiber-optic cabling has several advantages over electrical cabling:

• Because of its low-signal-loss and high-bandwidth properties, fiber-optic cabling is capable of longer distances and higher bandwidths.
• Fiber-optic cabling is immune to problems with EMI (Electro-Magnetic Interference) which can wreak havoc on signal integrity, especially over long distances.
• In dangerous environments like chemical plants, optical signals can't trigger an explosion though a spark.
• Because fiber-optic cables are non-conductive, they don't need electrical isolation, for instance between buildings where copper cables would require cross bonding to eliminate differences in earth potentials.
• Providing more security, it's more difficult to tap into a fiber-optic cable to read the data signals.
• Fiber-optic cables typically weigh less and this can make them easier to place.

Other extension technologies

While the combination of features provided by Matrox Extio is unique, there are other extension technologies. The existence of these other extension technologies is evidence that there's already a need to separate various hardware components over longer distances. These other technologies include cable extension, KVM extension, and bus extension. Each technology has advantages and disadvantages, but which technology to use depends on the requirements for a particular system.

Passive cable extension Cable extension simply involves the passive extending of cables over longer distances. These extensions are "passive" in that they don't involve extra devices to process the signals. Normally, monitor, keyboard, or mouse cables are less than 2 meters (6.6 feet) long and they're limited by the degradation of the electrical signal that occurs over longer distances. Some cable extensions are merely higher-quality cables with better contacts and insulation to minimize signal degradation. In some cases, this relatively low-cost solution may work well for short extensions, for example, going from 2 meters to 5 meters (16.4 feet). There are claims that higher-quality cables can support distances up to about 75 meters (250 feet) but, at such distances, the signal quality may be susceptible to many issues. With analog monitor signals, degradation problems such as blurring or ghosting may appear, while with digital monitor signals, problems may appear as dropped or blank pixels. The cost of simply longer cables is lower than other extension technologies, but the quality and reliability may be unacceptable at greater distances.

Passive cable extension (analog)

Active cable extension Devices may be available to enhance, boost, or otherwise attempt to improve the signal on a cable extension. This "active" type of cable extension may allow for longer distances but also increases the cost and/or complexity of the solution. Some overhead may be associated with such a process and this may result in performance issues. For example, USB repeaters are available that essentially resend the signals at intervals, but the usb.org FAQ advises to "not bother" with such solutions because they don't properly deal with maximum signal delay requirements in the USB specification.		USB repeater cable
For digital signals, there are solutions that convert an electrical cable signal to a fiber-optic signal and then back again to an electrical signal. For example, such solutions are available for DVI (Digital Visual Interface) monitor connections. This optical/electrical conversion process is similar to what Extio does but, with cable extension technology, this is limited to the cable for a single device. A fiber-optic cable extension offers the flexibility of extending a single device at a time and offers similar distances to Extio, but the price per device is higher and this solution is less integrated.		Fiber-optic DVI extension cable

KVM extension With KVM extension, the signals for the user-interface components of the computer – the keyboard, video (display), and mouse – are extended. To do this, the signals for these devices are serialized (made into a single, consecutive stream of data) and packetized (organized into small groups of data). To make the transfer of this large amount of data more feasible, lossless compression (compression with no loss of data) may also be applied to the data. This conversion process allows the data to be carried using network protocols over network cables, typically UTP (Unshielded Twisted Pair) cable or, more specifically, Cat-5 (Category-5) cable.		RJ-45 connector for Cat-5 cabling
The advantages of KVM extension over standard electrical network cabling are that the cabling is less expensive and already used in many environments. Further, because network protocols are used, network switching is possible and thus a point-to-point connection (a dedicated connection between 2 points) isn't required. The disadvantages of using network technology for KVM are that it introduces signal overhead and possible latency which could result in problems with performance and quality. This may be especially evident when using more than one display, higher resolutions, and/or longer distances. Fiber-optic technology can also be used with some KVM solutions but this negates the cost advantages of using standard electrical network cabling. While the "KVM" acronym implies that audio and other peripherals (for example, USB peripherals) aren't included, some KVM solutions may accommodate peripherals other than the keyboard, video (monitor), and mouse. By the same token, KVM technology can also be used on a subset of the keyboard-video-mouse mix. For example, some so-called "cable extension" solutions that act only on monitor connections are more like KVM solutions in that they involve the transmission of processed monitor signals using network protocols and connections. Specialized KVM solutions also exist to support more than one monitor at a time at a user station. However, such solutions cost more, may still not include all the functionality of Extio, and are more likely to encounter the bandwidth limitations of network technology.		KVM extension topology

Bus extension Another alternative is bus extension technology. As with Extio, bus extension involves the transmission of bus data over long distances. However, with bus extension, the data goes to remote expansion slots instead of remote graphics unit. The expansion slots are like the slots found inside a computer and various add-in cards can be added to them. In fact, Matrox graphics cards are often used with bus extension technology. To have the functionality of Extio, a multi-display graphics card, audio card, and USB controller card would have to be added. Even then, depending on the add-in cards chosen, all the functionality of Extio may not be there. With functionality comparable to Extio added to bus extension technology, the cost of such a solution may be more expensive. Bus extension technology offers flexibility but may be limited to one type of slot (for example, PCI), and the better integration of Extio makes setup, certification, and support easier.

Bus extension topology

Thin clients Finally, there's thin client technology. While this isn't necessarily considered an extension technology, it shares some properties with such solutions. With thin clients, a small, relatively inexpensive computer is at the user station and it's connected to a more powerful server through a network connection. Because of the limited capabilities of the thin client, some of its capabilities are provided by the server. For example, thin clients typically have limited local storage and rely on the server to run much if its software. The advantages of the thin-client approach are that each thin client is relatively inexpensive, network distances can be greater than with Extio, network switching can be used, and an administrator can manage most of the system from anywhere on the network. The main disadvantage of this approach is that performance is limited by the basic hardware in the thin client, the shared nature of the network, network protocol overhead, the latency associated with longer network distances, and the shared resources of the server. Thin clients are well suited for basic applications like word processing and database access while Extio may be better suited for applications that require more dedicated resources.

Thin-client topology

Advantage summaries

The following are summaries of the advantages of various technologies related to Matrox Extio.

Extio advantages

Separates user-interface components from the rest of the computer Matrox multi-display support Fiber-optic cabling     - longer distances     - higher bandwidth     - no EMI     - no sparking     - no conduction     - more secure     - easier to place

Integrated USB support Integrated audio hardware Passive cooling     - longer MTBF     - silent PCI and PCIe support Space-saving remote graphics unit Matrox certification and support Long Matrox product life cycles

Fiber-optic cables vs. electrical network cables	Fiber-optic	Electrical
Higher potential bandwidth
Longer potential distances at high bandwidth
Immune to EMI (Electro-Magnetic Interference)
No sparking
No electrical isolation required
Unauthorized tapping more difficult
Lighter cabling
Less expensive
More existing infrastructure
Easier to splice (shorten or lengthen)
Longer distances possible at lower quality

Extio vs. passive cable extension	Extio	Passive cable extension
All the advantages of fiber-optic cabling (see above)
More reliable
More integrated (one cable for several devices)
More modular (one cable per device)
Simple
Less expensive

Extio vs. active cable extension	Extio	Active cable extension
Less expensive per device (than fiber-optic cable extension)
More integrated (one cable for several devices)
More modular (one cable per device)

Extio vs. KVM extension	Extio	KVM
Less expensive with comparable functionality
Higher-quality, more reliable
More integrated (graphics hardware, audio hardware, USB)
Better performance
More flexible network configuration possible
Less expensive configuration possible

Extio vs. bus extension	Extio	Bus extension
Less expensive with comparable functionality
More integrated (several devices in one unit)
Smaller, more compact
Passive cooling
Better performance
More flexible (through different add-in cards)

Extio vs. thin clients	Extio	KVM
No special client-server software required
More powerful, dedicated resources
More flexible network configuration possible
Less expensive

* For stretched and independent mode support for quad-display products, click here. Earlier versions of Matrox Extio support a maximum resolution of 1600 x 1200.

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