I've had this Yamaha PortaSound PSS-460 since it was new, in 1986. I was just messing around with it last night and thought it'd be fun to record a little video of the Wallace & Gromit theme.

I'm using the "one-touch chord" method of the auto-accompaniment. The way it works is that a single note plays a major chord; a note with a white key below it plays a dominant chord; a note with a black key below it plays a minor chord. And I think a note with both a white and black below it does both effects, creating a minor chord with the minor 7th (such a chord was not needed to play this song).

Then I also turn on the "duet" mode which adds an appropriate harmonizing note to every melody note you play while the auto-accompaniment is on. (less info)