TEMPO controls the speed used by PLAY strings and other note-oriented generated sound. The value is beats per minute. A larger number plays the same music faster; a smaller number plays it slower.

Setting TEMPO changes the default used by later commands. Calling TEMPO as a function returns the current default, which is useful when a routine wants to save the old tempo, change it temporarily, and then restore it.

TEMPO does not make sound by itself. It changes how future note durations are interpreted.