Networking and Telecommunications

You will often have the need to connect your computer to other computers in order to share information. This is typically done with a connection to a data network, or with a connection over a telephone line.

Networking

A Local Area Network (LAN) is used to connect computers spread over a relatively small area, such as a university campus, or several offices in a building, or a home. The computers on the network can share data, and they can also access printers connected to the network. All of the computers and printers on the network are called nodes of the network. 

If your personal computer is connected to a network, it is called a network workstation (note that this is different form the usage of the term workstation as a high-end microcomputer). If your PC is not connected to a network, it is referred to as a standalone computer. 

In order to connect to a network, your computer will need a network adapter. This circuitry and port could be built into the motherboard or it could be on a network interface card (NIC) in one of the computer’s expansion slots. Your computer will also need the necessary networking software installed. Ethernet is the most common networking technology used. 

If the computers connected to a network have equal status, it is called a peer-to-peer network. A typical home network might be done this way.

Larger LANs usually have one or more computers that act as file servers to provide data and software to the other computers on the network. The other workstations are referred as client computers, and this is a server/client network. You may also find terminals connected as nodes on a network (terminals have only a screen and a keyboard, and no processing power; they connect over the network to a computer that does the actual processing).

At UNM-A, we have a server (named Chicoma, after the tallest mountain in the Jemez) on our campus LAN that validates your login name and password when you use one of our PCs as a client workstation, and provides files to network clients. Students can also use terminals in building 3 (if we still have any in Room 306) to connect to Chicoma to run software for some of our programming classes. In our Mac lab, we use a peer-to-peer setup to allow the students to get files from the teacher’s Mac.

It is also possible to do wireless networking, and you will see more of this in the future. A wireless LAN (WLAN) uses radio waves to carry the network traffic. They are usually based on the IEEE 802.11 specification, also called Wi-Fi.

Telecommunications

Telecommunication refers to transmitting data over a long distance. For personal computers, this usually entails connecting to other computers over a telephone line or other connection.

A telephone line carries an analog signal, one that has a continuously varying waveform. This is different from the discrete digital signals that represent numbers in your computer. To communicate over a phone line, you computer needs a modem (which stands for modulator-demodulator). The modem takes the digital information from your computer and modulates it onto an analog wave in the range of sound frequencies that can be carried over phone lines. The modem also takes analog signals from the phone line and demodulates them to extract the digital information, which it passes to your computer. The computer on the other end of the phone line is also equipped with a modem.

Computer modems typically communicate at 56K (56 kilobits per second), but if your phone connection is not good the modems will shift to a slower speed at which a reliable exchange of data can take place. A telecommunications connection via a phone modem is called a dial-up connection.

Many modems can also function as fax machines. You can “print” a document as a fax image to send to a distant fax machine.

Broadband
Many users found 56K telephone modem connections too slow (especially with increased popularity of the Internet). Broadband connections allow faster transfer of information. The most popular kinds are DSL, cable, and satellite. A DSL (Digital Subscriber Line) connection works over your telephone line and requires a special DSL modem. Unlike a regular modem, the DSL modem signal is carried at higher frequencies, beyond those of sound. It has a wider bandwidth since it is not limited to the audio band, and it has the advantage that you can use the telephone line simultaneously for voice and DSL communications. DSL requires special equipment installed at the phone company end, and you must not be located too far from the phone company’s junction.

A cable connection (requiring a special cable modem) uses your cable television line to transmit and receive data. Similarly, a link to satellite TV broadcast satellites can be used to provide broadband access to areas DSL or cable TV can't service.

Internet
One of the primary reasons for getting a network or telecommunications connection for your computer is to access the Internet. The Internet is a wide area network (WAN) that spans the globe and uses the TCP/IP protocol to transmit information. To access the Internet, you need a dial-up or broadband connection through an Internet Service Provider (ISP), or access to a network that has a gateway connection to the Internet.  Many information resources and services are available via the Internet; the two most popular are electronic mail (e-mail) and the World Wide Web (the Web). Both of these services use a client/server model: there are servers on the Internet that handle e-mail traffic or offer web pages. To access these, you need to run appropriate client software on your computer. Popular e-mail clients include Thunderbird, Apple's Mail program, and Outlook Express. World Wide Web client programs are called web browsers, and popular examples are Internet Explorer, Chrome, Netscape, Opera, Firefox, and Safari. Electronic mail entails sending and receiving private messages between users connected to the Internet. (This is different from public posting of messages on electronic forums such as Usenet Newsgroups or web forums.) Your messages are held for you on an e-mail server until you access them using you e-mail client software.  The World Wide Web is free-format a collection of data archives called web pages that include text, graphics, animation, sound, and video. Web pages are linked together using hypertext links (hyperlinks); simply clicking on a link displays another web page. All manner of information is available on the Web from individuals, businesses, universities, government bureaus, etc.