Cables & Ports

The Spaghetti Behind Your Desktop

You may heave heard their names, but you may not know what they are: USB, VGA, 1394, Ethernet, and so on. You may have noticed that there are several strange plugs in the sides or back of your computer, and you don't know what they are for. Knowing which cables to use can be important. For example, if you have a laptop, your computer can probably plug in to your TV and use it as an extra monitor.

There are several kinds of cablesthe wires with plugs at the ends you can use with your computer. Each cable type can be used for different purposes. To use a cable, your computer must have a porta "port" is a hole, or plug, in your computer which the cable hooks into. for that cable. Some computers have many cable ports, other computers only have a basic few. It may be important to know which ports your computer has.

The part of the cable you plug into devices is called a connector sometimes also a "jack" or a "plug".

Categories of Cables

There are several categories of cables, including:

  • Peripheral cables: used to connect computers to external devices like printers, mice, hard drives, etc.
  • Audio/Video cables: used to connect computers to computer monitors, TVs, microphones and speakers
  • Network cables: used to connect 2 or more computers together in a network

There are a few other categories which we will not focus on. One is "legacy" cables and ports, which refer to old cables and ports which are not used any more. These include serial, PS/2, parallel, and SCSI cables. You do not need to know them, although you may sometimes find them on your computer (especially desktop computers). Some computers still have them so you can continue to use older peripherals.

Peripheral Cables

Peripherala "peripheral" is a device which is outside the main computer box. Although monitors are peripherals, they have a different category of cable. cables are used for many devices, but especially for mice, keyboards, and external storage drives (HDD, DVD, etc.).

Today, there are two main cable types: USB"Universal Serial Bus" and FireWireAlso named "IEEE 1394" (for Windows PCs), and "iLink" (for video cameras). However, USB has become much more popular, and FireWire is dying out.

Name Symbol Image Other names Versions
USB Hi-speed USB (2.0), Superspeed USB (3.0) USB 1.0:
  • Released in 1996
  • Low-speed (mostly just for printers, keyboards, & mice)
  • Connectors are unusual: they have different shapes for each end; one end is for the computer, the other end is for the peripheral device
USB 2.0:
  • Released in 2000 (not fully adopted until 2003)
  • Hi-speed (could be used for almost any peripheral)
  • USB most popular
USB 3.0:
  • Coming out now, won't be fully adopted for a few years
  • "Ultra" speed (speed limit much higher then presently needed)
  • Slightly different shape for connectors
Firewire IEEE 1394, iLink Firewire:
  • Released in 1995
  • Hi-speed (same speed as USB 2 in 2000-2003)
  • Expensive
  • Used especially for HDD, DVD drives, and video transfer
Firewire B (FireWire 800):
  • Released in 2002
  • Double the speed of USB2, but not necessary for most
  • Mostly used by Apple (which helped develop it)
  • Different cable connectors
Firewire S1600 and S3200:
  • Released in 2008
  • Ultra-speed
  • Few people use them
  • Same connectors as FireWire B


Audio / Video Cables

You computer can connect to a variety of audio and video devices. Using the audio connectors (usually just a standard audio cable like you use every day), you can attach microphones, speakers, and other audio equipment. The video ports, however, are mostly just for sending video out to a TV or an extra monitor. It is possible to get video into the computer, but usually that requires a peripheral cable.

Here are the standard video and audio cables:

Type Name Connector Port Description
connect to a monitor/ HDTV
HDMI A new, high-speed video connector used with HDTVs. Recently, computers have included these. Has built-in DRM copy-protection. Carries audio and video.
DisplayPort Similar to HDMI, it can carry audio and video and has DRM copy protection. However, DisplayPort is cheaper.
DVI Digital connector, designed for better use with LCD monitors. It is capable of carrying an audio signal, but usually does not.
VGA Most common video monitor cable/port used for computers. Designed for CRTs, but can be used with LCDs. Carries video only.
connect to a TV
RCA Audio/Video combination. Yellow is video, red is right-audio, white is left-audio.
S-Video Video only (no audio). This is most common type of TV-out port on computers.
Audio Audio Used for mono/stereo audio. Most computers use this jack.

Right now we are in a transition, from old analog "analog" means that data is sent using different-sized waves. This usually means lower quality. "NTSC" TVs to higher-resolution digital "digital" means that the information is translated into numbers, meaning the data is usually exact and is clearly sent HDTVs. The old RCA and S-Video cables will disappear over time as old TV sets are discarded.

You should become familiar with what cable ports are on your computer. Depending on what ports your computer has, you can connect with a variety of displays and TVs. The ports will also tell you what kind of cables you will need to buy.

Many times, your computer's ports will not match the ports on a cable or TV. Usually, this can be fixed with an adaptoradaptors are available at electronic shops. You can find adaptors between most cable types, but not every one.--a cable which has one type of connector at one end, and a different type of connector at the other end. For example, there are cables which have an HDMI port on one end, and a DisplayPort connector on the other, as seen below.

Network Cables

Computers are able to connect together in groups so they can communicate. This is called a "network." When they are connected together in the same location, the network is called a LANLocal Area Network. The cables used to connect the computers in a network are called Ethernet cables. However, because Ethernet is universal, these cables are also called LAN cables and network cables.

Computers can be also connected in a LAN without wires. Without wires is called "WiFi"WiFi" is called musen LAN in Japanese. The name was chosen because it sounds similar to "HiFi," or "High Fidelity," meaning high-quality sound.."

Ethernet cables are very similar to normal telephone cables, except they have 8 wires inside instead of 4. Ethernet cables are also called LAN cables or Network cables. Below are images of Ethernet cables (at left), and telephone cables (at right) for comparison.

Ethernet / LAN / Network Telephone (not LAN)
connector port connector port

Each computer has one Ethernet port. Two computers can be connected directly, with only a cable. Three or more computers require a huba "hub" has many ports, and allows you to take a single cable and spread the connection to many cables to be used. Using a hub is usually very simple. Just connect the computers to the hub with Ethernet cables; the rest is automatic.

More will be explained about networks in the unit on operating systems.