Split stack control player pianos have the pneumatic hardware split into two pieces so that each half of the keyboard can be played independently to produce a number of musical effects. Pneumatic hardware consists of a foot pedal that operates an air bellows which forces air through the mechanism to move the keys.
Theme control pianos use pneumatic mechanisms in conjunction with special piano rolls to produce accented notes. The notes that make up a chord on these rolls are grouped separately so that the mechanism recognizes them as a chord.
Isolated theme player pianos are able to highlight and emphasize musical themes without segregating the notes of a chord. The background accompaniment is still heard, although more faintly.
Reproducing player pianos are fully automatic via electric motors, pneumatic devices and roll-coding. They can provide musical dynamics and tempo, giving the illusion of a live performance with no performer.
You can purchase a player piano kit to retrofit your piano and turn it into a player piano. All modern player pianos use microchips and MIDI to interface with a computer that controls musical playback. MIDI, Musical Instrument Digital Interface, is a music industry standard communications protocol that makes is possible for computers and MIDI instruments to work together to record and/or play music.