- Laurence Libin
Term for an inexpensive electronic keyboard built into a thin flexible membrane that can be rolled up and easily carried. Models of different sizes and capabilities typically encompass three to five octaves of near-normal-size flat keys and incorporate functions such as selectable tone qualities and rhythmic patterns, demo tunes, loudness control, metronome beat, vibrato, sustain, digital display, and recording and playback options. Some models can play MIDI files. Power is provided by batteries or by external sources such as a computer’s USB port. Sound is produced by a small internal loudspeaker or headphones, or the playing can be channelled through a computer, home audio system, or other device. While the least expensive roll-up pianos can be considered toys, better ones can be useful for practicing, composing, and entertainment when other keyboard instruments are not available....