METHOD AND APPARATUS FOR SYNCHRONIZED CONCURRENT PROCESSES

A synchronized concurrent process system incorporating a data driven control with a time attribute being assigned to the shared data. The term "data driven control" means a process operation sequence control system which satisfies the following three conditions. In condition 1, a process is allowed to initiate its operation when all the data items to be referred to by the process are generated by other processes; in condition 2, during a time period from when a processing initiates its operation to when the processing terminates its operation, the other processes are prohibited to update any data item to be referred to by the process, and in condition 3, only when a process terminates its operation, the other processes are allowed to refer to all the data items generated by the process. However, the data driven control alone is not satisfactory. Recognizing the existence of shared data, a time attribute (interior clock) is provided to discriminate the same data before and after updating. This provision has advantages: PA0 (i) The procedures for the synchronous control and the mutual exclusive control need not be inserted in an intermediate location of a program, PA0 (ii) all processes can operate concurrently (The wait state is not necessary); and PA0 (III) a computer system can be provided with the deterministic characteristic.