In 1981 my mother gave me this Casio VL-Tone musical instrument. It was one of the first electronic musical instruments and (drum roll) it was also a calculator. I still have and it works. It has several instrument sounds and rhythms. It also has the ability to shape your own waveform by setting the ADSR (Attack, Delay, Sustain, and Release). You can record melodies up to 100 notes long and play them back automatically as you played them in or you can play them back one note at a time.
In this sample I used the Swing rhythm and I set the ADSR to sound like a banjo. The instrument has a line out which I connected to my iMac. I recorded in Audacity.