Now remove the spacebar, combine the two buttons into a single one for "tone" and adapt it to morse code. All the buttons still do only one thing and now there's only one button!

And, you don't have to worry about what to do in the case that someone hits the "rotate ball" button while it's still rotating.

> And, you don't have to worry about what to do in the case that someone hits the "rotate ball" button while it's still rotating.

Eh, it's a pretty trivial problem, comptometers have it figured out more than a hundred years ago.