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Desktop Connectivity Type Overview

Laptops, Desktops and Office Equipment Connections

When setting up a new desktop or laptop computer, the many different connection types can become confusing. Often times more than one connection is available that can serve the same purpose. If the equipment being connected is outdated, it is possible that complications may arise from the lack of a supported connection types. This guide will help to indentify the purpose of the different connection types found on most computers and suggest options for connecting devices with different connector types.

Video Connections

Almost all computer systems have a 15-pin video connection known as VGA. This connection has been a standard in the industry for several decades for providing analog video. Although VGA actually refers to an outdated video format originally output through a 15-pin connection, the name continued on by users to refer to analog computer video. To make installation easier for users, manufacturers typically follow a color code scheme described in the PC 2001 standard. Computers and components manufactured following the PC 2001 standard, will color code the VGA connector in blue. Cabling is secured to the computer or monitor by thumbscrews that are located at both sides of the connector. Although there have been many attempts in the industry to phase out VGA from computers, its reliable performance and distance capabilities have kept it around for longer than expected. By 2015, VGA will begin to phase out of existence on new computer hardware as many manufacturers have banded together to discontinue support of this video connection.

Some computers and monitors have a connection known as DVI for video output. DVI stands for Digital Visual Interface and was introduced in 1999 to support flat panel LCD monitors. Although a DVI connector can be on either a laptop or desktop computer, it is more common on a desktop computer because of its large physical size. DVI connectors are available in several different configurations such as DVI-D, DVI-I, dual Link and single link. However, DVI-I is the most common DVI connection found on computers and monitors. Since DVI-I supports both analog and digital, if a computer monitor only has VGA, a DVI to VGA adapter cable can be used to make a connection. Manufacturers following the PC 2001 standard will color code a DVI connector in white to indicate digital monitor output. Similar to VGA, the connector is secured to the computer and monitor using thumbscrews on both sides of the connector.

Although S-video is primarily a video connection for consumer audio/video equipment, it has been implemented on many laptop and desktop computers for the purpose of outputting video to a television. The low resolution picture quality is not ideal for most computer content, but it does work well for applications such as slideshow presentations, movies, and video games with decent results. The S-video connection is held in place only by friction, causing frustration since the connection frequently becomes unplugged. Computers that have VGA only can use a device called a "scan converter" to acquire an S-video output. New connection types such as HDMI and DisplayPort have replaced the S-video connection on laptop computers for television output and will work well for all content types.

HDMI, originally released for use in connecting consumer audio/video equipment, is now available on many new computers for the purpose of outputting audio and video to a High Definition Television (HDTV). Similar to S-video, the HDMI connector is held in place by friction and can result in frustration from becoming unplugged accidently. Because HDMI is a digital signal, it is only compatible with DVI by means of a cable or adapter. For computers that do not have an HDMI connection, a VGA to HDVI converter device can be installed or a new graphics card can be added. Since HDMI supports a copy protection algorithm called HDCP, computers equipped with a Blu-ray drive can output protected content to an HDTV. Without HDCP support, Blu-ray movies are incapable of outputting at full resolution.

Released in 2006, DisplayPort is the most recent addition to the category of video connections. With a single cable,DisplayPort can reduce clutter in desktop applications by allowing a single cable to carry audio, video and peripheral signals. Unlike VGA and DVI, which use thumbscrews to install, DisplayPort is held in place with a locking tab, which reduces time during installation and removal. This is also an improvement over S-video and HDMI's friction-held design that results in accidental removal. Using an adapter, DisplayPort can be converted to VGA, HDMI or DVI, providing compatibility for multiple monitor types. Multiple monitor setups can be easily created by chaining monitors together, eliminating the need for additional hardware. On select model of graphics cards and computers, the DisplayPort connection can be of a smaller design and appearance called Mini DisplayPort. The Mini DisplayPort is growing in popularity due to its compact design and is used in the new ThunderBolt desktop connectivity solution.


In the late 1980's the PS/2 connection was introduced as a means for connecting a mouse and keyboard to a computer. Although it was replaced by USB technology in the late 1990's, it still remains on many desktop computers. Manufacturers following the PC 2001 standard will use purple to indicate a keyboard connection and green for a mouse. Many computer manufacturers are scaling back on implementing PS/2 connections on new computers since USB has become the favored connection type.

The most popular and widely used connection on the back of a computer is a connection known as the Universal SerialBus (USB). USB was introduced in the late 1990's to eliminate the complexity of installing peripherals. Using a hub device the number of USB ports can be theoretically expanded up to 127 on a single computer. USB is commonly used to connect peripherals such as keyboards, mice hard drives and printers. Since its introduction, USB has undergone several revisions to accommodate the need for increased bandwidth and power. Since USB devices are not backward compatible with older technologies, computers without USB ports will need to install a USB host adapter card to use USB devices. USB can, however, adapt to older devices such as parallel printers, serial modems and PS/2 keyboards and mice.

IEEE-1394 also known as Firewire, DV, or iLink was developed by Apple and released in the mid 1990's as a faster solution than USB technology. Initial IEEE-1394 standards had a transfer rate that was 33 times faster than USB's initial standard that had a maximum transfer rate of 12 Mbps. This gain was short lived when the release of USB 2.0 surpassed IEEE-1394 by 80Mbps contributing to USB's strong lead as the preferred connection type. To compete with USB 2.0, an 800 Mbps version of IEEE-1394 was released using a 9-pin form factor connector. Recently, the release of USB 3.0 again surpassed the transfer rate of IEEE-1394 standard with a rate of 4.5Gbps. Although fewer devices are entering the market today with IEEE-1394, it is still available on many computers for transferring video from digital camcorders and external hard drive bay enclosures. Due to the differences in signaling and standard between IEEE-1394 and USB technology, the two are not adaptable to one another. As a result, computers without IEEE-1394 ports will need to install an IEEE-1394 host controller card to use equipped devices.

As technology matured, hard drives became faster at accessing data than it could transfer back along IDE cabling. The need for a faster hard drive interface gave rise to the wide spread implementation of Serial ATA, also known as SATA. SATA currently offers the fastest connection type available and has a transfer rate of 6Gbps. Although it is most common as an internal connection, an external version was introduced to allow the use of external hard drives. The external version is referred to as eSATA with the "e" indicating external. By using a combination of USB and SATA technology together, eSATAp supplies power to devices without the need for a separate cable. Since SATA drives are not compatible with older technologies, SATA drives must be connected to a SATA or SAS controller. Computers without either controller type will need to add an upgrade card. Since SAS controllers are primary an interface on enterprise server systems, a SATA controller will be the most compatible and cost effective upgrade option for a desktop user.

In the past, peripherals such as modems, joysticks, or printers were connected by either a DB25 or DB9 connection. Both connection types supported only one device connection at a time. If a device needed to be removed and a different one connected in its place, a reboot was necessary for proper operation. Some devices required a unique cable that was specific to a manufacture's requirement. Both connection types have been phased out and are rarely available on new computers. Users that have older devices with these connection types can use a USB adapter solution to allow a connection to a new computer.


To connect to the internet and share devices and files, the RJ45 connection is used to connect to a wired LAN. The connection, which appears similar to a large telephone jack, can achieve a transfer rate up to 1Gbps in most consumer applications. Although many computers utilize 802.11 technologies (Wi-FI), to connect to a LAN, RJ45 is often preferred because of its fast transfer rate and reliability. Users that wish to use a wired connection, however their computers lacks an RJ45 connection can install a USB adapter solution.


Sound has become an important part of most computer setups for media content such as music, video, presentations and video games. The most common audio connection on a computer for the past several decades has been the 3.5mm audio jack. This connection is commonly used for desktop speakers and headphones, however using a 3.5mm to RCA adapter cable, can allow for a connection to a larger audio system.

Although the 3.5mm jack is beneficial for a simple stereo audio desktop speaker setup, applications in which a computer is part of a home theater setup will have requirements that cannot be fulfilled by a single stereo audio connection. To support high performance audio setups, digital audio connections are becoming more popular on new computers. A digital audio connection type can be either an orange colored RCA known a digital coax, or an optical connection called Toslink. Digital audio has the ability to support multiple audio channels found in 5.1 or 7.1 surround sound tracks. If the digital connection does not match on both pieces of equipment, then a bi-directional digital audio adapter can be installed.

This white paper is for informational purposes only and is subject to change without notice. C2G makes no guarantees, either expressed or implied, concerning the accuracy, completeness or reliability of the information found in this document.