Assertion: piano's keyboard | /r/HasProperty | upgrade
Facets:
value: to the yamaha pss-7
type: OTHER
Source sentences:
text: The Yamaha PSS-14 and PSS-15 keyboards were upgrades to the Yamaha PSS-7 and were notable for their short demo songs, short selectable phrases, funny sound effects and distortion and crackly sounds progressing on many volume levels when battery power is low.