zlacker

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+(OP)
I heard stories about this type of troubleshooting used in production from a colleague and friend about 40 years senior to me.

>>gmueck+(OP)
This reminds me of something really cool I saw a while ago but I can't find for the life of me, it was a bit of JavaScript that ran in the browser and could be used to send a signal to a nearby AM radio! I can't remember quite how it worked, but I tried it and it definitely did after turning off my monitor which apparently pumps out shit-tons of interference into the bottom end of the mediumwave band. I do remember that it was a demonstration of a security vulnerability for supposedly airgapped systems.

>>BoxOfR+k3
The first time I ever saw something like this was a program called Tempest for Eliza, which would generate patterns on a CRT screen that could be captured by an AM radio.

The website appears to still be available at:

http://www.erikyyy.de/tempest/

>>gmueck+(OP)
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 :)

>>gmueck+(OP)
In case anybody is interested, the museum is http://www.computermuseum-stuttgart.de/

>>gmueck+(OP)
This is probably one of the most relatable things I've ever read about that era of computing, it reminds me of setting up fun little git hooks and devops events to play sounds at various stages. Amazing.

>>gmueck+(OP)
I used to tune my shortwave radio to various frequencies emitted by my ZX Spectrum +2A. It had terrible shielding!

You could hear the noise/tone change with various different types of computation, and for some frequencies listen to the framebuffer scanout (I think) where the sound appeared to match the display changes. Definitely not in the UHF range of the actual signal though.

>>chenxi+xk
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.

>>gmueck+(OP)
AM Radio Computer Music:

Conway's Game of LIFE in a DEC PDP-7 w/ Type 340 Display

https://www.youtube.com/watch?v=hB78NXH77s4&ab_channel=Livin...

Early computer graphics -LIFE - 4 Gosper Glider Guns on a DEC PDP-7 Type 340 display

https://www.youtube.com/watch?v=JhvOw7vW4iA&ab_channel=Livin...

DEC PDP-7 w/ Type 340 display running Munching Squares and Spirograph

https://www.youtube.com/watch?v=V4oRHv-Svwc&ab_channel=Livin...

Also PDP-7 related (but with more melodic music), here's a video remix I made of an early CAD system called PIXIE (with the first known implementation of pie menus, using a light pen) running on a PDP-7 with a type 340 display, networked with a Titan mainframe, at the University of Cambridge (one of the first network distributed graphics systems), set to music:

https://www.youtube.com/watch?v=jDrqR9XssJI&ab_channel=DonHo...

>>gmueck+(OP)
What we can do with EM radiation has always seemed so cool to me. It's just crazy how all this info is just flying through the air without us even noticing (without tools of course).

>>gmueck+(OP)
The GHC manual has this to say about the `-B` flag:

> -B > > Sound the bell at the start of each (major) garbage collection. > > Oddly enough, people really do use this option! Our pal in Durham (England), Paul Callaghan, writes: “Some people here use it for a variety of purposes—honestly!—e.g., confirmation that the code/machine is doing something, infinite loop detection, gauging cost of recently added code. Certain people can even tell what stage [the program] is in by the beep pattern. But the major use is for annoying others in the same office…”

https://downloads.haskell.org/~ghc/latest/docs/html/users_gu...

>>grafs5+aM
> without us even noticing

If only we had two receptors on the front of our face that were capable of detecting EM radiation with wavelengths between 380nm-700nm.

>>BoxOfR+k3
It's https://fulldecent.github.io/system-bus-radio/ (https://github.com/fulldecent/system-bus-radio)

>>gmueck+(OP)
During particle physics experiments, the number of reactions of interest that get detected is an important thing to monitor. If you stop measuring the reaction of interest, it might mean that a magnet drifted out of preferred tuning, that your data acquisition crashed, but the key thing is that something requires human intervention to fix. Frequently, the trigger signal, which has a short pulse anytime data are to be collected, would be sent into a speaker. You get a buzzing, not unlike a Geiger counter at high rates, which blends into the background noise, and that tells you how healthy the experiment is.

The funniest thing was seeing how everybody was paying attention to that buzzing at all times. You could have a dozen people talking about different aspects of the experiment, but if that buzzing drops out for a few seconds, every single conversation immediately stops. Usually it would come back after a few seconds and the conversations would resume, but it was fascinating to have visible proof that everybody was ready to drop their current work in order to get the experiment running again if anything happened.

Edit: I also heard tales of somebody who had trained themselves to wake up if the buzzing ever stopped. That way, they could take short naps during the night shift, while still being present and ready to resolve any issues that came up.

>>8192kj+cW
I think you know what I'm getting at though

>>8192kj+cW
I don’t have a problem imagining that, but it would be amazing to have receptors that can detect EM radiation below and above 380-700 nm.

>>chenxi+xk
I used exactly this phenomenon on my XPS13 to know when my Gentoo was in the "merge" phase of an ebuild (distinctive noise generated by copying a large amount of files).