CPS100 • Introduction to Computers


Lakeland College • Japan Campus

Cables, Connectors, and Ports

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.


The Spaghetti Behind Your Desktop

There are several kinds of cables you can use with your computer. Each cable type can be used for different purposes. To use a cable, your computer must have a port (a hole, or socket, which the cable goes 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

Peripheral 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 FireWire (alternately called "1394" on PCs). However, USB has become much more popular, and FireWire is dying out.

Name Images Versions
USB

[Hi-speed USB (2.0), Superspeed USB (3.0)]

Computer connector:




Peripheral connector:



USB 1.0:

  • Released in 1996
  • Low-speed (12 Mbps), for printers, keyboards, & mice
  • Different shapes for the computer and peripheral connectors

USB 2.0:

  • Released in 2000 (not fully adopted until 2003)
  • Hi-speed (480 Mbps), could be used for almost any peripheral
  • USB most popular
Computer connector:




Peripheral connector:



USB 3.0:

  • Connectors are blue
  • "Ultra" speed (4 Gbps)
  • Slightly different shape for connectors



USB 3.1:

  • Uses Type-C connector, similar size to mini/micro connectors
  • Higher "Ultra" speed (10 Gbps)
  • Connectors are reversible
The cable type below, Firewire, is mostly discontinued, but is still found on many computers.
Firewire

[1394,
IEEE 1394,
iLink]




Firewire:

  • Released in 1995
  • Hi-speed (400 Mbps)
  • Expensive
  • Used especially for HDD, DVD drives, and video transfer



Firewire B (FireWire 800):

  • Released in 2002
  • Double the speed (800 Mbps)
  • Mostly used by Apple
  • Different cable connectors; not backwards-compatible

Firewire S1600 and S3200:

  • Released in 2008
  • Ultra-speed (1.6 & 3.2 Gbps)
  • Few people use them
  • Same connectors as FireWire B


There are a large number of "mini" connectors for USB and other cable types. The more common USB connectors are:


Tech in Your Life

Never Works on the First Try

Isn't this just so true?

There is one way to plug in a USB cable the right way on the first try: look at the connector for a logo. The logo, which is always on a specific side of the connector, usually goes up. However, this does not always help, as some USB ports are sideways. In such a case, if you use the port often, you can try to remember which side it "up."

There is another way, however: a new type of cable becoming available: reversible USB. This allows you to plug in a USB cable correctly on the first try.

The new USB 3.1 Type C connector (pictured previously on the page) is also reversible, but has not yet been widely used.


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
Video:
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. Part of the new Thunderbolt technology.
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.
Video:
connect to an old analog 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 "NTSC" TVs to higher-resolution digital 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 adaptor—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 LAN (Local 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.

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 hub (a device to connect multiple devices) 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.



Other Ports

There are a wide variety of cables, and it would be impossible to review them all quickly. However, here are a few more cable types that you might encounter on your computer:


Thunderbolt Now found mostly on new Macintosh computers, Thunderbolt is a recently-released high-speed peripheral cable. This cable is able to connect to a variety of devices, including video, network, and storage devices; the idea is to consolidate cables into just one, instead of having several different cables connected to the PC.
S/PDIF S/PDIF (Sony/Philips Digital Interconnect Format) is a special audio connector; instead of plugging in several cables, you can use this one cable (either co-axial or optical) for home-theater sound output.
PC Audio ports


On Windows PCs, especially on the rear panel of desktop machines, audio ports are often color-coded. While some may only have two audio ports (line out / speaker-headphones, and line-in / microphone), some have three to six, and these can be used for home theater sound systems. Very simply, the colors represent:

  • Blue: Stereo Line In; plug in audio-out from CD players and other devices
  • Green: Stereo Line Out; use for speakers or headphones
  • Pink: Microphone
  • Orange: Subwoofer and Center out
  • Black: Rear Surround Speakers for 5.1 and 7.1 home theater systems
  • Gray: Middle Surround Speakers for 7.1 systems (not included if the computer only allows for 5.1 systems)
LEGACY PORTS (ports which are old and often not used any more)
PS/2 PS/2 ports were used for mice and keyboards. This is perhaps the most common legacy port; it can still be found on most desktop computers. It is a very low-speed "serial" connector, which works fine with keyboards and mice, because they do not transmit much data and do not require high-speed connectors. Although any PS/2 device can be used with a PS/2 port, color-coding usually indicated that purple ports are for keyboards, green ports are for mice, and both colors together can be used for either.
Parallel Parallel cables were often used with printers, and may still be on some devices to allow the use of very old printer devices used by some people or companies. It is becoming more uncommon, perhaps due to the fact that its large size takes up too much room on a motherboard.

Terms to Know

cablea wire with connectors at either end, used to transfer data from one device to another.
porta hole or socket in a device which can receive a cable connector.
connectoralso "jack" or "plug"; the metal part at one end of a cable which plugs into a port on a device.
peripherala device outside the computer's main chassis.
networkmultiple computers connected together so they can share data.
USBthe most popular peripheral connector, used on virtually every personal computer as well as many other devices.
Firewirea high-speed peripheral cable, now relatively unused.
HDMIa high-speed HD video and audio cable, used especially for televisions and gaming devices.
DisplayPorta high-speed HD video and audio cable, not very common; now part of the newer Thunderbolt technology.
DVIa digital video cable.
VGAan older analog video cable; very standard, it can be found on most video devices.
RCA (composite)a set of cables used for low-definition video and audio.
S-Videoa now-rare type of low-definition video cable.
LANLocal Area Network; a group of computers in a building which are connected together to share data.
Ethernet cablealso called a "LAN cable" or "network cable"; the common cable type used to connect computers in a local network.
huba device which allows multiple devices to connect to each other.
Thunderbolta new, high-speed peripheral cable (found on all new Macintosh computers) capable to connecting multiple peripherals of various types; newer types use fiber-optic connections.
S/PDIFa high-quality audio connector.
legacy cables/portscables and ports which are outdated and no longer used; some computers offer these ports to allow the use of old equipment.
PS/2a mouse and/or keyboard connector.
parallela legacy peripheral connector.
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