Yamaha DX-21

first example

second example

http://www.vintagesynth.com

Specifications

Polyphony - 8 notes

Oscillators - 4-Operator Digital FM synthesizer

#Instruments - (1) Monotimbral

Filter - None

Effects - Chorus

Keyboard - 61 Keys (no velocity/aftertouch sensitivity)

Memory - 128 patches and 16 performances

Control - MIDI (w / Velocity and Aftertouch)

Date Produced - 1985