A method of electronically controlling the operation of an internal combustion engine is effected on the basis of results of arithmetic operations of digital control quantities derived from detected operating conditions of the engine through digital processing operations. The digital processing operations are subdivided into a number of tasks in dependence on the control functions to be performed. In addition, these tasks are subdivided into a plurality of priority levels. The memory has a task control block having run or execution flag areas in response to the priority levels and start request flag areas in response to the tasks, the start request flag areas being classified in accordance with the levels, in order to make it easy to correct, alter or add tasks. An order for starting the execution of the task is always controlled in accordance with the condition of the run flags and the start request flags.