The Data Processing Unit DPU controlling the Recovery System of Sounding Rocket 8 Project is developed on the microcontroller operating system LUTOS. Under the structure of LUTOS, user designs the system software by signal flow functional block diagram. LUTOS system provides programming templates to connect the information flow nonsequentially within one time slice according to the definition of functional block diagram like analog electronic circuits. The processing of information data streams is implemented by LUTOS as tasks whose executions are switched efficiently by LUTOS time slicing scheduler driven by hardware timer interrupts. The operating system allows user control the scheduling of tasks either by interrupts or by polling to satisfy the real-time requirement of individual task. Design of programming structure by state machine completes II the details of software analysis. The feature of B2BBus provides a buffer mapping mechanism of data exchange in a multi-CPU construct.