« Mainly a great songwriting tool. »

Every review I see of the Casio PT30 (including the ones on this site) seem to miss the point of this brilliant little instrument. It was mainly marketed at the time as an aid to songwriting. This is because you can input (or "record") a melody into the memory, press the "chord" button, and it will play back your melody FULLY HARMONIZED. Yes, it will it will come up with chords that fit your tune! The chords are also shown on the display, so you can note them down for use with "real" instruments. It will even change individual chords if you don't like the ones it chooses - you press the "change chord" button at the point you want the change to occur and it will select another chord (or you can even make your own chord substitutions by inputting using the chord keys to the left of the keyboard).

As such this keyboard was great for budding songwriters who could come up with a tune but were unable to figure out a suitable chord accompaniment for it.

Yes, the keyboard tones, rhythms etc are a bit cheap & nasty sounding (though they can be made to sound good through a decent amp) but that wasn't really the point of the instrument.