Overview

A LAN differs from the mainframe network in that there are no centralized processors. All processing is performed on stand-alone computers and workstations. The LAN interconnects these computers, allowing them to share files and communicate with one another.

All applications used by computer users are located on individual personal computers and workstations. This means that if the LAN should fail, the computers are still operational; they just cannot communicate with one another. The popularity of personal computers (PCs) led to the development of LANs, and today, the LAN industry has far outgrown the mainframe industry.

One disadvantage of a LAN is the cost. Although the network costs are relatively low, the cost of individual computers can be rather high. In the mainframe environment, users communicate via terminals, which cost a few hundred dollars. In the LAN environment, users communicate through PCs and high-powered workstations, some costing over $10,000 (depending on the applications for which they are used). Even a simple computer with relatively low processing power can cost a few thousand dollars.

Another disadvantage is the support cost of PCs. Applications continuously change, requiring upgrades. Often these upgrades require additional memory, forcing users to purchase additional memory chips for their computers. The cost of memory has not come down significantly, often costing as much as a new computer itself. Mass storage is fairly cheap, but memory is still rather expensive.

Still, when compared to the ongoing cost of mainframe equipment and productivity loss, the cost of LANs is really...