Data communications

When ``digital computer´´ was an institutional rather than a household word, the machine required some very special personnel to cajole anything from its limited facilities. The operators came to the computer and spoon-fed it. And the computer´s limited ``brainpower´´ permitted only one operator at a time to tinker. Today, computers can be programmed so that almost anyone can be trained to access them¿at least, in a limited way. Moreover, these electronic machines now have such massive central and peripheral memories that many people can use them simultaneously. Since it is impractical to have all of the computer users make a pilgrimage to the computer, the computer is made to come to the people that it serves. This is done via communication channels¿predominantly in the telephone network. The various factors involved provide the substance for this primer article.