Computer Network
Computer networks have been a boon for businesses because they connect different makes and models of microcomputers, minicomputers or even mainframe computers, allowing for shared communication, files and equipment. The first networks appeared in the 1960s when multi-user networks were introduced. In multi-user systems, dumb terminals, which do not have processing capabilities of their own, are connected to a central host computer, which shares processing time with these dumb terminals. Now much more popular are Local Area Networks, or LANS, which appeared in the early 1970s. A LAN is a communication network privately owned by the organization using it. LANs utilize stand-alone microcomputers rather than dumb terminals and can vary greatly in size, range and complexity. The actual distance and number of computers that can be connected is highly dependent upon the type of LAN and communication line used. Telephone lines are sometimes used and are most convenient; however, coaxial cable connections permit faster, higher quality transmissions. Fiber optics, tiny tubes of glass half the diameter of a human hair, has become the preferred technology of the 1990s, allowing faster and less expensive data transmissions than wire cabling. All networks are different in size and complexity. However, they all share one of three similar shapes. These shapes are known as network topologies. There are three basic topologies to which most networks conform: Bus, Ring, and Star. The Bus topology uses a single communication line to connect equipment, allowing contact between all stations, or nodes. Failure of a single micro-computer may interfere with the rest of the network.
A Star topology consists of several microcomputers connected to a centralized networking device called a hub. This acts as a crossing guard for network traffic. Star topologies may also allow the computers to connect to a centralized host computer, called the file server, which shares its files among all users of the network. A variation of this, the Multistar network, has several file servers connected to each other, yet each also has a Star network of its own. Star networks are more costly to install due to the extra cabling involved, but are frequently used among retail stores having several branch outlets. The third topology, the Ring, is somewhat similar in design to the Bus topology. Each computer is connected to two other computers and can communicate and share files with any station in the network. However the two ends of the Bus are connected together, making the Bus into a Ring. A Ring network is slower and more expensive to install than the Star, but it is also more reliable, since alternative paths exist if a communications line is interrupted. A modification on the Ring network is the Complex or Distributed network. Communication lines connect all stations in the network, but on the downside, installation is complicated and requires high maintainance. LANs offer many benefits within companies, industrial sites, college campuses and hospitals, allowing for more efficient and convenient computer services. Future predictions call for worldwide interconnected networks resembling the telephone systems of today. Accessing these networks will likely become just as commonplace as making a telephone call. One application of networking, electronic mail (E-Mail), introduced in the early 1970s, is very popular among businesses. E-mail service allows letters to be sent across the United States for less than the cost of mail, with the added advantage of arriving within seconds. Another popular offshoot of networking are Information Networks, such as America Online, CompuServe, or Prodigy, wherein computer users may access a wide variety of computerized services, including E-Mail, investment advice, reference and travel information, shopping and much more.
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