The widespread use of the UNIXsystem ritchie thompson bstj 1978 within Bell Laboratories has produced problems of software distribution and maintenance. A conventional mechanism was set up to distribute the operating system and associated programs from a central site to the various users. However this mechanism alone does not meet all software distribution needs. Remote sites generate much software and must transmit it to other sites. Some UNIXsystems are themselves central sites for redistribution of a particular specialized utility, such as the Switching Control Center System. Other sites have particular, often long-distance needs for software exchange; switching research, for example, is carried on in New Jersey, Illinois, Ohio, and Colorado. In addition, general purpose utility programs are written at all UNIXsystem sites. The UNIXsystem is modified and enhanced by many people in many places and it would be very constricting to deliver new software in a one-way stream without any alternative for the user sites to respond with changes of their own.
Straightforward software distribution is only part of the problem. A large project may exceed the capacity of a single computer and several machines may be used by the one group of people. It then becomes necessary for them to pass messages, data and other information back an forth between computers.
Several groups with similar problems, both inside and outside of Bell Laboratories, have constructed networks built of hardwired connections only. dolotta mashey 1978 bstj network unix system chesson Our network, however, uses both dial-up and hardwired connections so that service can be provided to as many sites as possible.