The VL-1 was actually the first instrument of Casio’s VL-Tone product line, and was also a functioning calculator!  VL-1 sounds created by filtered squarewaves with varied pulse-widths or vintage Pulse Width Modulation (PWM).

Sounds included:

• Piano
• Violin
• Flute
• Guitar
• ADSR
• Fantasy

An advanced unit, it featured a programmable synthesizer which provided for oscillator waveform and ADSR envelope (VCA) selections.

Fun Fact:
German band Trio used the VL-1 in the hit song from the 80′s “Da Da Da”.