Program control system in multitask environment

A program control system in a multitask environment wherein operational programs respective for machine tools or industrial robots are allowed to be executed in parallel in an environment where a plurality of programs can be executed, comprising:

• program execution control means for controlling an execution of a plurality of programs;
• a first program of said plurality of programs which is activated for execution as an originating task by said program execution control means and includes a subtask execution command indicating an activation of another of said plurality of programs and a wait command indicating a temporary stop of execution of said first program;
• subtask execution recognition means for recognizing said subtask execution command in said first program during the execution of the first program;
• a second program of said plurality of programs which is activated for parallel execution as a subtask by said program execution control means in response to the recognition of said subtask execution command in said first program by said subtask execution recognition means, and includes an end command indicating a completion of a task in said second program associated with a task in said first program;
• and
• resumption control means for recognizing said wait command in said first program during the execution of said first program and for recognizing said end command in said second program during the execution of said second program,
• said program execution control means for temporarily stopping the execution of said first program in response to the recognition of said wait command in the first program by said resumption control means and for resuming the execution of said first program in response to the recognition of the end command in said second program by said resumption control means.