 | PS/2 Ports |
| VGA Monitor Port |
| Parallel Port |
| Ethernet Port |
| S-Video Port |
| DVI Monitor Port |
| USB Port |
| Firewire IEEE 1394 Port |
| Modem RJ-11 Port |
| Mini Audio Jack |
| Routers/Switches & Hubs?? |
Clear Your Mind of Cable Clutter
Back in the early days of computing, it was an easy task to hook up your
PC system (as long as you knew which fitted where as they were not colour
coded). You just had a few peripherals like a
keyboard, mouse,
printer and
modem to connect, and a corresponding number of cables. Now the
landscape has changed drastically, with a proliferation of exciting new
wireless, video and audio enhancements, along with the cables and
connectors to go with them. We now have to deal with USB, FireWire,
network jacks and an assortment of audio and video connections.
Complicating the picture is the fact that many of the audio and video
connections look identical, but serve different functions. The once simple
job of connecting cables has turned into a headache! Not to worry -
we have created this handy little guide to help clear your head of all the
cable clutter.
PS/2 Ports
The PS/2 Ports are simple, 6-pin, low-speed connections commonly
dedicated to a keyboard and
mouse. Although these ports may look identical at first glance, they
are not interchangeable, so you'll need to attach the keyboard and mouse
to their respective PS/2 port. Luckily, all modern computers have
colour-coded connectors, with
keyboards designated as
light purple, with a computer
mouse using
green.
If you elect to use a USB keyboard and mouse, you can typically disable
the PS/2 ports in the system's CMOS set-up and free the PS/2 system
resources for other devices.
VGA Monitor Port
Video Graphics Array: used to connect a CRT monitor or LCD to the computer.
DB25 Parallel Port
The parallel port is not usually supported on modern PCs. Typically used for printers, but also used by some Zip drives, the modern range of printing equipment has preferred to use USB connectivity for single PCs, with network capabilities via Ethernet and wireless for a growing number of network-enabled printers. You'll find some printers do include parallel connections for older computers.
RJ45 Ethernet Port
A local-area network (LAN) architecture developed by Xerox Corporation in cooperation with DEC and Intel in 1976. Ethernet uses a bus or star topology and supports data transfer rates of at least 10 Mbps, with higher rates on Fast Ethernet and Gigabit Ethernet standards. Ethernet is the most widely implemented LAN standard.
A modern version of Ethernet, called Fast Ethernet (or 100Base-T), supports data transfer rates of 100 Mbps, typically compatible with standard Ethernet connections.
The best new major version is Gigabit Ethernet, supporting data rates of 1 gigabit (1,000 megabits) per second.
S-Video Port
Short for Super-Video, a technology for transmitting video signals over a cable by dividing the video information into two separate signals: one for colour (chrominance), and the other for brightness (luminance). When sent to a television, this produces sharper images than composite video, where the video information is transmitted as a single signal over one wire. This is because televisions are designed to display separate Luminance (Y) and Chrominance (C) signals. (The terms Y/C video and S-Video are the same.)
Computer monitors, on the other hand, are designed for RGB signals. Most digital video devices, such as digital cameras and game machines, produce video in RGB format. The images look best, therefore, when output on a computer monitor. When output on a television, however, they look better in S-Video format than in composite format.
To use S-Video, the device sending the signals must support S-Video output and the device receiving the signals must have an S-Video input jack. Then you need a special S-Video cable to connect the two devices.
DVI Monitor Port
Commonly used for flat-screen TFT/LCD monitors, as opposed to the VGA connection which is dedicated to older (CRT) monitors. Short for Digital Visual Interface, a digital interface standard created by the Digital Display Working Group (DDWG) to convert analogue signals into digital signals to accommodate both analogue and digital monitors. Data is transmitted using the transition minimised differential signalling (TMDS) protocol, providing a digital signal from the PC's graphics subsystem to the display. The standard specifies a single plug and connector that encompass both the new digital and legacy VGA interfaces, as well as a digital-only plug connector. DVI handles bandwidths in excess of 160 MHz and thus supports UXGA and HDTV with a single set of links. Higher resolutions can be supported with a dual set of links.
USB Port
Universal Serial Bus: a protocol for transferring data to and from digital devices. Many digital cameras and memory card readers connect to the USB port on a computer. A single USB port can be used to connect up to 127 peripheral devices, such as mice, modems, and keyboards. USB also widely supports Plug-and-Play installation (reducing the need to install special software for connectable devices) and hot plugging (removing and adding of devices without the need to switch off or restart your machine).
These days, you're likely to find USB ports on the front of your machine, as well as the back, as USB devices are universally popular and are in frequent use. Older USB ports will typically be USB 1.1, supporting data rates of up to 12Mbps. Just about every USB device and computer sold these days will work at the high-speed specification of USB 2.0, capable of transferring data at a rapid 480Mbps.
Firewire IEEE 1394 Port
Very similar in principle to USB, FireWire is a type of cabling technology for transferring data to and from digital devices at high speed. Commonly used with digital camcorders, FireWire is the best way for your PC to capture video, allowing you to edit the video footage, and to record onto DVD-R once the data is inside your computer, using appropriate programs. Also known as IEEE 1394, FireWire was invented by Apple Computer but is now commonly used with Windows-based PCs as well.
Modem RJ-11 Jack
The presence of this usually indicates that you have an internal modem, giving you up to 56kps internet access through dial-up. RJ-11 is short for Registered Jack-11, a four- or six-wire connector used primarily to connect dial-up modems and other telephone equipment. RJ-11 connectors are also used to connect some types of local-area networks (LANs), although RJ-45 (Ethernet) connectors are more common.
Mini Audio Jack
With just about every sound card, you get three 3.5mm sockets. The green socket is known as the 'line-out' socket, and is the most commonly used, as it outputs audio from the PC. Ready for headphone or speaker usage. The blue socket is 'line-in' and as the name suggests, does the opposite of line-out, by acting as an audio input, so you can play audio and have it recorded in certain PC sound programs, using this connection. The pink socket is also an audio input device, and is designated for analogue microphones.
Routers, hubs and switches are all parts of the hardware that makes up a computer network.
Routers
A
router allows connectivity to one or more computers, helping create
a network. For home users, these are particularly useful for taking a
single broadband internet account, and spreading it to at least two or
more computers. Standard routers require the internet connection from a
standalone
modem, but modem-routers are increasing in popularity, which can be
plugged into any broadband-enabled phone line, reducing cable clutter,
and only taking up one power socket.
In the telecoms industry, the backbone of the internet is formed by
industrial routers. They work rather like telephone exchanges, passing
data between network segments to form a connection. Each router has a
configuration table, or routing table, containing information on which
connections lead to certain groups of addresses, which connections have
priority for usage, and rules for handling different kinds of traffic. A
typical home/office router has a very small routing table, but the big
routers that handle the main internet traffic can have huge complicated
routing tables. Each time a router receives a packer of data it will
attempt to send it along the best possible route to its destination,
based on its routing table. If that connection is not currently
available it will send it along the next best route. In this way, the
routers that form the internet can reconfigure the paths packages take
to work around any problems with the network.
The rules for handling traffic are an important part of internet
security. A home/office router may have rules limiting how computers
outside the network can connect to computers inside the network, as well
as preventing private network traffic from spilling into the outside
world. Many home routers include additional security features - they
scan and filter all traffic that passes through them, usually through an
integrated
firewall in the hardware. Some may carry out other useful roles such
as acting as a print server.
Wireless
routers have become more common. A
wireless router does exactly the same job in the home as a regular
wired (Ethernet) router, with the difference that a computer can be
connected to it without needing to run Ethernet cable between the
computer and the router. All you need is a wireless network adapter in
each PC you want to connect, usually in the form of a card in your PCI
slot (or a
laptops's PCMCIA card slot) or an adapter for USB. Wireless routers
generally have four ports to connect Ethernet cable as well, so
computers can be connected by whatever means is most convenient - you
might want to use a cable for your desktop PC which sits right next to the router, but use the wireless
adapter in your laptop.
Switches
A
switch is sometimes called an 'intelligent hub', and now that they are
no longer significantly more expensive than hubs they have almost
replaced them entirely. A switch does the same as a hub, in that it
connects devices to allow them to act as a single segment. However, it
does not automatically send traffic to every other port. Each time a
frame of data comes into the switch, it saves the physical address (MAC
address) and the port it came from in its MAC address table. It then
checks the destination MAC address in the table, and if it recognises it
it sends the frame to the appropriate port. If it is not in the table,
or the address is a broadcast address (intended for every machine on the
local network), then it does the same as a hub and sends the frame
through every port except the originating port.
Hubs and switches are commonly used in businesses to divide up the local
network into a number of subnets. For example, if the creative team are
frequently exchanging large files across the network, their traffic will
slow down the network for other users. Two switches can be used, with
the creative team's computers being connected to form one network while
everyone else's computers are connected to form another. The two
switches can then be connected to the router which sits between the
internal network and the internet. The creative team's traffic is only
seen by the computers on that network, but if they need to connect to a
computer on the other network the data is sent through the router in the
middle.
Hubs
A
hub is a device for connector multiple eEhernet devices (usually PCs) to
form a single segment - a portion of a network that is separated from
other parts of the network. It has multiple ports through which devices
are connected, and when it receives data it sends it out again through
every port except the one it came in through.
Originally Ethernet networks used coaxial cables. Each computer was
fitted with a transceiver, which connected directly into a long piece of
coaxial cable - a bus. This meant that traffic on the network was
visible to every other computer. A hub replaces this cable, making sure
that traffic is seen by every computer on the network, and enables the
network to be connected in the form of a star rather than a bus using
the familiar twisted pair Ethernet cable.