The present invention provides data processing technology for making two or more processing units cooperate with one another such that output data from respective groups of processing units (GSM) are merged by a respective sub-MG (merger), data from the sub-MGs are merged by a main MG, and the merged output data are displayed on a display unit. Each GSM initiates drawing processing assigned thereto in response to the reception of a drawing enable signal and, after execution of the processing, outputs a drawing end signal. The GSMs to which the drawing enable signal is to be sent, and the GSMs from which the drawing end signal is to be received, are set for each application. A main SYNC sends the drawing enable signal to corresponding GSMs in the order of setting for an application in response to the reception of a processing request from the application, while it receives the drawing end signal from the corresponding GSMs so that the processing results of the GSMs will be displayed on the display unit.