casio vl.10

http://www.polynominal.com/casio-vl10/

http://www.matrixsynth.com/2014/04/rare-casio-vl-10-keyboard-synthesizer.html

"The smallest keyboard instrument ever made! 29 keys (buttons), 3 different sounds, and 10 drum rhythms. Plus, it's a calculator! 

The Casio VL-10 VL-Tone synthesizer is one of those bizarre frankensynths of the 80′s, part calculator, part synthesizer, part drum machine. This keyboard is one of the smallest if not the smallest fully working synthesizers every created. 

This particular unit is in perfect working condition. There is a little dent in the metal on the underside, but otherwise it's in great shape. (Yes, metal. Not plastic like the VL-1.) 

There is an excellent video of the VL-10 here: