Song from an Old Casio Keyboard.?

Back in the 80's, my mother purchased a keyboard from Casio. The factory demo song was very catchy. Just recently We had heard the song on A companies Hold music, and I began to search for the song. Does anyone have any info on how so search for a plain piano song, with no words (Ive google Searched Casio and a lot of the models, we cannot find out the model). Any advice would help.}!