The Yamaha PSS-15 is a portable keyboard synthesizer released in the early 1980s. It was used by many popular musicians, including Michael Jackson, Prince, and Depeche Mode. The PSS-15 is a monophonic synthesizer with a built-in speaker and a two-octave keyboard. It has a variety of features, including a built-in rhythm machine, a pitch bend wheel, and a built-in chorus effect. It also has a built-in arpeggiator and a built-in sequencer. The PSS-15 is powered by four AA batteries and can be connected to a computer or other MIDI devices.