This paper describes recent large-scale-integration programmable processors designed for multimedia processing such as real-time compression and decompression of audio and video as well as the generation of computer graphics. As the target of these processors is to handle audio and video in real time, the processing capability must be increased tenfold compared to that of conventional microprocessors, which were designed to handle mainly texts, figures, tables, and photographs. To clarify the advantages of a high-speed multimedia processing capability, we define these chips as multimedia processors. Recent general-purpose microprocessors for workstations and personal computers (PCís) use special built-in hardware for multimedia processing, so the multimedia processors described in this paper include these modified general-purpose microprocessors. After briefly reviewing the history of programmable processors, we classify multimedia processors into five categories depending on their basic architecture. The categories are reduced instruction set computer (RISC) microprocessors for workstations, complex instruction set computer microprocessors for PCís, embedded RISCís, low-power digital signal processors (DSPís), which are mainly used for mobile communications devices, and media processors that support PCís for multimedia applications. These five classes are then grouped into two: microprocessors with a multimedia instruction set and highly parallel DSPís. An architectural comparison between these two groups on the basis of Moving Picture Experts Group decoding applications is made, and the advantages and disadvantages of each class are clarified. Future processors, including ďsystem on a chip,Ē and their applications are also discussed.