Minicomputer is a relative term by today's standards. These antiquated machines were developed in the 1960s and used heavily into the 1980s when they were replaced by personal computers. Minicomputers were compact alternatives to the large, room-sized computers of the same era. Costing somewhere in the neighborhood of $20,000 through the 60s and 70s, minicomputers had limited functionality and were used for three primary purposes -- process control, data management and communications.
Minicomputers were often used in manufacturing for process control. A minicomputer used for process control had two primary functions -- data acquisition and feedback. For example, factories used minicomputers to monitor the manufacturing process. If an element of the process slowed, stopped or accelerated, the computer recognized the change and made necessary adjustments to the system.
Minicomputers used for data management could acquire data, generate data or store data. For example, the PDP8 computer bought in the early 1970s by the Wesson Memorial Hospital in Springfield, Massachusetts, was used to generate and store radiation treatment plans for patients and as a database of all patient tumors and related information.
Minicomputers were also used as communication tools in larger systems, acting as a "portal" between the human operator and a larger, central computer or processor. The user could run operations such as error checking, polling and line buffering through the minicomputer and then use the device to make system adjustments to the central computer or processor.