The research examined distributed computer based process control systems. A functional analysis was done to identify the subunits that make up such a system. They are: i) a communication system ii) a distributed database iii) a presentation system for a) the process b) the process engineer c) the process operator Each of these subunits is discussed in detail in chapters 3-7. An economic analysis was also carried out to determine the optimum distribution of the control task. It was concluded that, on present costs, each controller should contain eight control loops. The controllers and man machine interfaces should be distributed along a multidrop communications line. Based on these analyses, a system was implemented within the department. It used an M6800 microcomputer for the controller and the departmental PDP11 minicomputer for the man machine interfaces. The result proved to be effective, especially the process operator's interface. This used a colour graphics CRT with touch sensitive screen and ten key keyboard. This input system minimised training and, combined with the three level hierarchical displays, provided an efficient work station.