Preliminary design studies have been carried out on the control system for an 800-Mev proton linear accelerator based on the use of an on-line digital computer as the main controlling element. The accelerator system is divided into fifty-two subsections or modules. A module has complete control of all the equipment associated with it. Selected data and monitoring signals are transmitted on a time-shared basis to a central control computer. The functions which the computer performs in the control of the accelerator may be classified into Operational Control, Operational Supervision, and Data Monitoring and Handling. The operator gives instructions to the computer through interrupt lines. Commands to the modules and displays for the operator time-share a common channel in the computer output system. Synchronization of the input and output data flow is controlled by the computer through a timing unit. A comparison has been made of the computer-based control system with a possible alternate system which does not use a computer. The computer replaces much of the control and data handling equipment required by the alternate system. As a result, the costs of the two systems are comparable. However, the computer-based system is preferable since it has many functional advantages over the alternate system.