1. A processing apparatus for a digital television (DTV) to process a DTV stream, comprising: a demultiplexing unit for retrieving a service information from the DTV stream; a memory coupled to the demultiplexing unit for storing the service information; a first processor coupled to the memory for assigning a task by sending a command according to the service information; a second processor coupled to the memory for handling the task according the command; a communication unit coupled to the first processor and the second processor, for receiving the command from the first processor and sending the command to the second processor; and at least one function module controlled by the second processor, to process the task.