So I decided that I wanted to play the piano. And for the first year at least of my piano lessons my practice instrument was a Casio CZ-101. Not perhaps the ideal mechanism for building finger strength/dexterity as it has half sized, un-weighted keys, and only 48 of them. Has a pitch-bend wheel.
It did have some pretty decent square and saw wave synth sounds and you could even alter them or make your own. I wrote my first song on it.
Recently I had it hooked up to GarageBand as a midi controller and it works like a charm.
Comes with an original cartridge for ROM storage. Runs on D-batteries or its replacement adapter.