The sound made by your computer could give away your encryption keys…
One of the processor’s address lines was wired up to a speaker inside the teletype, producing an audible click every time that address bit changed.
The idea was that you could, quite literally, listen to your code running.
Loops, in particular, tended to produce recognisable patterns of sound, as the program counter iterated over the same set of memory adresses repeatedly.
This was a great help in debugging – you could count your way through a matrix multiplication, for instance, and keep track of how far your code ran before it crashed.
You could even craft your loops (or the data you fed into them) to produce predictable frequencies for predictable lengths of time, thus producing vaguely tuneful – and sometimes even recognisable – musical output.
Plus ça change, plus c’est la même chose
So it was with considerable amusement that I read a Full Article Here