Communication networks for computer communication generally connect office machines or factory machines. LANs (local area networks) are now common in corporations and public institutions. Such networks usually do not have switches like phone networks. A common type is a loop in which messages from the sender travel until they reach the receiver station. The loop is analogous to a party line of telephone. Digital data and text communication between machines generally does not require a continuous open channel because the recipient usually will tolerate a time delay between the time the message is sent and the time the message is received. Consequently, such communication can be broken down into standard sized packets which can be sent individually from sender to receiver. One advantage of packet communication is that it provides a mechanism to correct errors or if this can not be accomplished, resend the packet until it is communicated without error.
Packet communication in telephone networks is very different from continuous voice communication, which requires a continuous open line. In contrast, each packet can travel a different route thought the communication network. For example. some packets can travel from New York to Los Angeles through Chicago and some through New Orleans. When they arrive all the packets can be assembled into the original message.
The technological frontier is the creation of wide area networks, WANs. Developing WANs is very different from developing LANs. When a LAN is wired into an office, the installers usually use a high capacity line such as coaxial cable or optical fiber. Such LANs have a large capacity. Communicating between offices generally requires renting a line from the phone companies. Capacity is expensive. Consequently developers of WANs must focus on compressing messages to make efficient use of expensive connecting lines. Another problem is the lack of protocols to connect the wide variety of LANs together.
A very important type of computer communication is electronic mail, which is the transmission of text messages through computer networks. Originally corporations created internal worldwide corporate E-mail systems. For example, TI set up its own electronic mail and filing system that connects 50 plants in 19 countries. When set up it could process 10,000 messages and 8c, now but it now can process 33,000 messages at 4c. Alcan installed a $500,000 system for sending orders and inventory information between all its branches and warehouses.
The effectiveness of E-mail is documented by an IBM technical person's comparison of two projects he worked on at IBM. The first was the proposed development of a new type of computer terminal in the late sixties. The first draft of the proposal took three days. The draft was sent to various IBMers in the US, Canada, and Europe. Two months later they met for a conference. Every two months they got together to discuss the next draft. Two years later the paper was published. Ten years later the same technical person prepared another paper. Using materials on disk, he finished the paper in one hour. He sent the paper to 25 people via the IBM network. Two hours later he read all their responses, modified the speech, and redistributed it. In one day he made five passes and was complete. (What the report does not tell you is how high the technical person had risen in the hierarchy. I assume he had become so powerful that people would respond quickly. While this does decrease the wonders of technology, the example serves to demonstrate the efficiency of electronic mail.)
Currently their are numerous E-mail systems in information utilities such as CompuServe, Prodigy and Internet. The use of E-mail should explode in the 1990s because of the adoption of the world standard, x.400 and the creation of E-mail directories under the x.500 standard. The adoption of a standard means inter institution E-mail communication becomes as easy as intra institution E-mail today. Gradually intra institutional E-mail systems will either adopt the x.400 and x.500 standards or create an interface making their internal systems externally compatible with these standards.