zlacker

>>tobr+(OP)
The funniest demonstration that I watched was at the computer museum at the University of Stuttgart (it's just a single room, but it contains a lot of history!). The guide took an old, butchered radio that was reduced to a coil attached to a speaker and put on top of the front panel of a PDP-8. Then he started a Fortran compiler, which would take several seconds to complete. During that time, the radio made kind if hideous digital beeping noises from the CPU's EMV radiation that got picked up by the coil inside. You could easily learn to distinguish different compiler phases and tell whether the program made progress. The guide explained that this was a common way for operators back in the day to keep track of the jobs they were running while taking care of other tasks: were they still running? Did they get stuck? Did the job complete and is it time for the next one? Some inventive guys figured out that when you wrote certain instruction sequences, the EMV noise would become tonal and the pitch could even be tuned to some extent. That got them to write programs which would compute nonsense, but when you picked up the EMV emissions, you would hear music! The museum guide ran a few of these programs to our great amusement :).

I've yet to see this mentioned - or demonstrated - anywhere else.

>>gmueck+PG4
Not nearly as cool as your what you described, but I took advantage of the horrible coil whine on my Dell XPS 15 9560. The Intel CPU, Nvidia GPU, and Toshiba SSD all had different pitches of coil whine. Based on the pitch and volume, it was very easy to tell which component was being stressed :)

>>chenxi+m15
I can relate. Around the time I got this tour of the museum, I was working on a rendering algorithm that was slow and could occupy the GPU for seconds at a time. For some reason- whether it was a poorly stabilized power supply or EM radiation I do not know - I could hear pretty loud chirping noises when I had my headphones plugged into the onboard analog jack. It went so far that I could easily tell which part of the algorithm was currently running on the GPU and I could sometimes even count single iterations. This was very helpful because the screen was of course frozen. while the GPU was busy with my program.

This computer finally made me buy an external audio interface out of frustration. I went on to do some acoustics projects and I really needed cleaner audio for them.