The basic section of the multimedia data-processing system includes a CPU 1100, an image display unit 2100, a unified memory 1200, a system bus 1920, and devices 1300, 1400, and 1500 connected to the system bus. In this configuration, the CPU is formed on an LSI mounted on a single silicon wafer including instruction processing unit 1110 and display control unit 1140. Main storage area 1210 and display area 1220 are stored within the unified memory. Unified memory port 1910 for connecting the corresponding LSI and the unified memory is provided independently of the system bus intended to connect the LSI and the input/output devices. The unified memory port can be driven faster than system bus.