HP Princeton HP-21 - Manual (Page 16)

Repeat the demo song
When a demo song is playing, press the
[REPEAT] button to set the beginning point
that you want to listen. "r-A" will appear on
the display, then press the [REPEAT] button
again to set the end point of the
playback."r-B" will appear on the display and
the selected section of the demo song will
playback repeatedly.
This function does not work after pressing the
[DEMO ALL] button and its songs are
playing.
Adjust the tempo of demo song
When a demo song is playing, you can adjust
its tempo by pressing the [TEMPO +/-]
buttons.
10. Foot pedals
The piano has 3 Piano foot pedals - soft pedal
，
sostenuto pedal and sustain pedal.
Soft
Pedal
Sostenuto
Pedal
Sustain
Pedal