CPU time
For task management, a combination of preemptive and cooperative multitasking was chosen, which makes different task priorities possible. Preemptive means that tasks are interrupted after a certain amount of time by the operating system, in order to share the CPU time with other tasks. Cooperatively means that a task stops using CPU time by itself. It does that, if it's finished with its current job or waiting for a certain event. Because of this combination it is possible to assign priorities. Tasks with low priority get CPU time only if all tasks with higher priorities are not then working.