A central processing unit (CPU) for an MP3 player and a karaoke system makes it possible to reduce the size of the MP3 and the karaoke system by integrally building various kinds of storage units in a DSP and an RISC processor for executing control commands and generating control signals. The CPU 100 includes a display device 160; a microphone 140; a loudspeaker 170; a data storage unit 130 for storing real-time recorded data inputted through the microphone and wave sample data for synthesizing sounds of musical instruments, and also storing a background image, a caption, and font data, which are visually and aurally provided to the user; a main storage unit 120 for sharing the sample data of the data storage unit 130; an RISC processor 102 for storing sound sources, which output information corresponding to sound pitches and volumes of musical instruments, in the form of a MIDI file; a DSP 101 for synthesizing the data outputted from the main storage unit and the RISC processor to provide the music desired by the user; a codec HO for converting an output of the DSP; and an USB input/output terminal 103 for connecting the CPU to external devices.