It played over the piezoelectric motherboard speaker, the one that usually emits only a beep, and is intended to play a given frequency for a given duration. I

It played over the piezoelectric motherboard speaker, the one that usually emits only a beep, and is intended to play a given frequency for a given duration. It's possible to use pulse width modulation to make mediocre digitized sound come out, but it is quite complex and would use a lot of BIOS space. A simple sequence of notes, however, is compact and easy.