VS1103 is a license free audio IC with MIDI / ADPCM / WAV audio decoder and ADPCM encoder on a single chip. It can handle upto three simultaneous audio streams or act as a MIDI synthesizer. The IC contains a high-performance, proprietary low-power VS DSP 4 processor core, 5 KiB instruction RAM and 0.5 KiB data RAM for user applications, serial control and input data interfaces, 4 general purpose I/O pins, an UART, as well as a high-quality variable-sample-rate mono ADC and stereo DAC, followed by an earphone ampli?er and a common buffer. The VS1103 receives its input bitstreams through serial input buses, which it listens to as a system slave. The input streams are decoded and passed through digital volume controls to an 18-bit oversampling, multi-bit, sigma-delta DAC. Decoding is controlled via a serial control bus. In addition to basic decoding, it is possible to add application specific features, like DSP effects, to user RAM memory.