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 (plug) for that cable. Some computers have all kinds of cable ports, other computers only have the basic cable ports. 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").
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
- Legacy cables: old cables which are not used much any more
Peripheral Cables
| Name | Symbol | Image | Other names | Description |
| USB |  |
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--- | There are two types: USB 1.1, and USB 2.0. Version 1.1 is very slow, and is use donly for mice & keyboards. Version 2.0 is very fast. |
| Firewire |  |
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IEEE 1394, iLink | There are two types: Firewire 400 and 800. The 400 version is very fast, but the 800 is even faster, and is used mostly by professionals. iLink is widely used for digital video cameras. |
Firewire 400 and USB 1.1 both came out in the late 1990's. At that time, USB was only fast enough for devices like mice, keyboards, and printers. Firewire was about 40x faster, and so was used for external hard drives, optical drives, and video transfer.
A few years ago, both types were upgraded. USB 2.0 was released, and the speed was about the same as Firewire 400. Today, USB 2.0 is quickly becoming the standard cable for most devices, though many devices can use both USB 2 and Firewire.
Firewire 800 was also released. It is about twice as fast as USB 2 and Firewire 400, but most people don't need such high speeds. Firewire 800 is used mostly by people with special high-speed data transfer needs.
More images can be found below.
Audio/Video Cables
Video cables are the important point here. There are two basic types:
- cables to connect to a TV set (non-HDTV)
- cables to connect to a computer monitor or an HDTV
Each type has two cables. For connecting a computer to a TV, you can use RCA or S-Video cables.
For connection a computer to a computer monitor or an HDTV, you can use VGA or DVI cables.
| Type | Name | Plug | Port | Description |
| Video: connect to a TV |
RCA |  |
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Audio/Video combination. Yellow is video, red is right-audio, white is left-audio. |
| S-Video |  |
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Video only (no audio). This is most common type of TV-out port on computers. | |
| Video: connect to a monitor/ HDTV |
VGA |  |
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Most common video monitor cable/port used for computers. Designed for CRTs, but can be used with LCDs. |
| DVI |  |
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Digital connector, designed for better use with LCD monitors. | |
| Audio | Audio |  |
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Used for mono/stereo audio. Most computers use this jack. |
Most people with notebook computers want to connect them to a TV at some point. To do this, you need either an RCA or S-Video cable. Most computers with TV-out ports use S-Video. You must be careful, though--there are different kinds of S-Video cables. Talk to the people at the electronics store to make sure you have the right one.
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NOT ON THE TEST: Because S-Video does not include audio, you also might use an audio cable. If you only need video to go from your computer to the TV, then an S-Video cable only would be fine. If you want video and audio, you should do this:
First, I buy an S-Video-to-RCA adaptor. This can be the hardest: you must make sure that the cable is exactly right for your PC. Ask at the store where you buy it. (For Macs, you should get this from the Apple store.) The other parts are standard: one audio-to-RCA cable; one very long (3m or 5m) RCA A/V cable, and then two (or three) female-to-female RCA connector adaptors. Why do I recommend this? The long RCA cable is convenient to go all the way to the TV set. You could use a long S-Video cable from the PC to the TV, but then you would need a second cable for audio. The way I do it, the audio and video become combined in the RCA cable. |
Network Cables
Computers can be connected in a LAN in two ways: with or without wires. Without wires is called "WiFi" (see next page). With wires is called "Ethernet."
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.
| Ethernet | Telephone | ||
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| 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 to be used.
Using a hub is very simple. Just connect the computers to the hub with Ethernet cables; the rest is automatic.
Hubs are very useful for computer labs, or for connecting all the computers in entire buildings. Here is a layout of the computer network at LCJ:
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The diagram at left shows the LCJ network in rough detail. The red objects belong to the student network, and the blue objects belong to the office network. The big squares on the 2nd floor are the servers, or "boss" computers of each network. The circles are computers; triangles are printers; and green diamonds are Ethernet hubs.
All the objects of the same color can communicate with each other. For example, a computer on the 1st floor could open a document saved on the server on the 2nd floor, then print it out on a printer on the 8th floor. The servers, in turn, are connected to high-speed fiber optic cables (not shown) connected to the Internet. |
All the cables joining these computers are Ethernet cables.
Legacy Cables & Ports
"Legacy" cables are older cables and ports which are not used much any more. These include Serial, Parallel, and SCSI cables and ports.
Serial and parallel cables were too slow to keep. Parallel and SCSI cables were big and heavy. And all three cables were not "hot-swappable."
What is "hot swap"? Today, USB and Firewire cables can be connected and unplugged at any time, without turning off the computer; this is called "hot swapping." Legacy cables were not hot-swappable, which means that every time you wanted to plug something in or unplug something, you had to turn off the computer, do the plugging, and then turn the computer back on again. That was very inconvenient.
You will see serial and parallel ports on the back of most Windows computers; they are kept to help people with old equipment. However, they are disappearing as time goes on. Macintosh computers removed all legacy ports more than 6 years ago.
| Serial | Parallel | SCSI |
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Depending on what you want to do with your computer, the various ports may or may not be necessary for you. Check the computer you will buy to see what ports it has!
REFERENCE CHART (see the cable chart in your classroom for a better look):
| ports |
cable connectors |
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| USB |
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| Firewire (also called IEEE 1394 and "iLink") |
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| Network (Ethernet) |
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| Network (Telephone) |
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| Audio In and Out |
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| Monitor (VGA) |
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| Monitor (DVI) |
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| TV (S-Video) |
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| TV (RCA) |
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