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Hardware

Making Music with CPU Activity 83

Posted by CmdrTaco from the fun-and-games dept.
Tails writes "Ever wonder how you could make that useless radio interference your CPU generates into interesting noise? Forcing operations on his CPU and Memory bus, Berke Durak has made a tunable FM signal out of the radio activity his motherboard creates.. " Didn't we see this stuff in Triumph of the Nerds? Looks nifty tho.
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Making Music with CPU Activity More

Making Music with CPU Activity

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  • The entire musical output of Fatboy Slim
    Well, now, that's not that great a feat.


    --
  • My dad's workplace used to have a mini (couldn't identify the type... I was very young at the time) that would play the Star-Spangled Banner on the AM band when it was shut down for the night. I think it was the same one where its only response to any kind of syntax error was "EH?", on the theory that, 90% of the time, you'd know what you did wrong without being told...

  • The discussion in the messages had very little to do with music from system noise.

    The topic under discussion was software that secretly transmits information by taking advantage of the radio emissions.

    The music angle is a simple diversion/nostalgia trip, think security!

  • The problem there is that you'll only get the masking signal while rc5des is scheduled. If someone is running a process on your machine that transmits data, their reciever will allready be set up to reject that along with random signals caused by other processes.

  • Perhaps one of the cheezier sound cards would make a good reciever. They seem to pick up all sorts of EMI anyway.

    That is interesting about the unused address. Perhaps later today, I'll hack a module together to probe non-existant addresses. It may or may not pick anything up, but it might also make a good test for poorly designed MBs

  • One of the messages was talking about generating an FSK signal. It should be possable to hook an AM radio up to a sound card, and decode the resulting audio signal. Hmmm....caffine kicking in...

  • train the signal analysis software to recognize certains actions by pattern matching?

    Intriguing possability!

    I wonder if adding a random element to the length of each timeslice in the scheduler would make such an analysis harder?

  • What if they aren't running some for of *NIX? We resort to the trivial solution ;)

    ;)...

    The random timeslice does look tempting. It MIGHT have a detrimental effect on system performance, but I doubt it would be severe. The real question is a good fast source of randomness. Perhaps a really hot cup of tea.....

  • Shades of Cyrptonomicon and "Van Eck Phreaking." It would be interesting to build a simple receiver that demodulated the signal. It might be just as interesting to find if any common subsystems are vulnerable to interference in such a way that they could act as passive receivers. We would have a little Sub Rosa LAN. Then we could write a TCP/IP stack to use the new hardware layer and blow the whole bandwidth on intra office spam and instant messaging. I doubt we could use it for Quake :P
  • Alas, playing music is indeed an old hack. I remember listening to Christmas songs on an AM radio sitting on the console of an RCA 301 in 1965.

    I was just cleaning out the garage and in a box of old stuff, I found my 1966 offer letter from Control Data. I left RCA and joined them on 6-6-66 at the grand salary of $505 a MONTH.

    That was after my first real hack: A friend and I managed to program a 301 in machine code so that we could scroll messages across its memory display lights. We put the program in a test station 301 at RCA with the message "Call John at 555-1212" running - it was the phone number of the CDC recruiter!

  • TPA 70 (Score:1)

    by Zigurd ( 3528 )
    In 1980 (yeah, carbon date this, buddy), I was working at a UN boondoggle in Austria called the International Institute for Applied Systems Analysis. There I saw two very interesting minicomputers, one was a Czechoslovakian copy of a PDP-11, and the other was an original Hungarian design called a TPA-70. This charming machine had a volume and tone control on the front panel. I cannot remember if it was an AM radio receiver or a 1-bit hack making the sound, but I think it was AM noise from the memory. I still have the manuals somewhere in a box in an attic...
  • I seem to remember reading an article a while back about the new high-frequency SVGA monitors.. and how with the appropriate receiver, the signal could actually be mirrored via radio waves as far as 150 feet away.... through walls and what not. it all depended on how many monitors were in the vicinity and broadcasting noise on the different frequencies....

    Proof that a system is still insecure, no matter how much you do to it.

    Of course, I guess a large issue, is what exactly is all the EMF doing to our bodies? The normal level of background EMF is much lower than what we currently bombard ourselves with from all directions.... oddly enough, I know people who think that microwave radio transmitters ony transmit from the transmitter straight to the little dish.... there's no overage.. no.. none at all... and if you move the dish.. I guess the transmitter is smart enough to move the signal....

  • I've heard that if you record the frequencies from your CPU, and play them backwards, you get scary Pro-Microsoft and Pro-Intel babble. :)

    -- Give him Head? Be a Beacon?

  • Anyone remember Dancing Demon for the TRS-80 model 1?
  • ``The entire musical output of Fatboy Slim can be...''

    Don't you mean Root Boy Slim???

  • Back in the mid '80s I was working on some early GPS equipment (large 19" rack mount stuff) that was being controlled with a PDP-11. We were located in southern Ohio where it turns out that damned few radio stations broadcast past, say, 1:00 AM. In the middle of the night it got pretty damned boring sitting around collecting data with nothing to listen to. Since we usually had to track satellites in the wee hours (since the full complement of SVs hadn't been launched yet) we sometimes kept ourselves amused by turning on a radio in the lab that would pick up the emissions from the PDP as well as the GPS receivers. After a little while you could tell what part of the control software was running, whether the receivers were tracking a satellite that was rising or one that was setting, and whether they'd switched to a different satellite.

  • Or at least with my old p90 I could. Whenever my computer was doing something processor/memory intensive, I could hear it making a strange sound.

    I can also hear my video card making a sound when things are drawing to video memory. Actually, maybe it's the bus that makes the sound.

    I can also hear things like CRTs scanning. I always know which TVs in the house are on.
  • We have never been able to positively identify where the sound came from exactly, but we are pretty sure it was the RAM. It was not the power supply and there was no harddrive in the system.

    It was probably the bypass capacitors for the RAM. DRAMs produce large current spikes when they are accessed and capacitors can behave like electrostatic speakers.

  • sounds amazing. and as someone who listens to ambient techno and thinks speaker feedback sounds nifty, i want some CPU noise to listen to in the car.. :)

    i'd try it myself but i'm on a mac and i doubt this is the kind of thing that would work on all versions of linux. maybe later i'll reboot into linuxppc, download it and see if it compiles.. but even so i doubt a 75 mhz machine will reach up into the FM band, although the CRT version might work.

    <ramble>
    anyway, this might be a great source of random audio for the one-time-pad security thing mentioned in the other article today. put an FM radio in the audio-in jack and run SETI@home or something complex to ensure the sound coming out the CPU will be random and unreproducable. Or run RC5, just for the sheer irony value of cracking one type of encryption and generating another in the process. If OTP were actually something useful, that would be a great idea.. -_-
    <ramble>

  • Yeah, my dad and I did that on ours like 15 or 20 years ago.

  • ...with a Beowulf cluster!



    ---
  • If you get a pair of cheap computer speakers you can do this too. I remember my Soundblaster 16 making noise when my video display had a large write to it, and when I read from my sbpcd. Anyway, isn't this a violation of FCC regulations? I thought it was, in the part about this device may not make any interference, and must accept all incoming interference?
  • Indeed, this is an old, old trick...and why it gets attention here is beyond me.

    There's even a name for it. "The Voice of God" trick... I've used this technique to determine if hardware is working when you have absolutely no other way of determining the health of a system. For example, I picked up an SGI Indigo 2 at a surplus auction a while back.. didnt have a keyboard, a monitor, or a mouse to plug into it. I basically had a power light, and thats it. Putting an AM radio in close proximity to the motherboard and tuning it to a clear frequency will result in your being able hear the motherboard go through its self check. If you hear nothing, the board is dead. If you hear alot of chatter happening on the bus, you can be fairly certain the machine is at least salvagable.

    Now, if this guy were to have actually written code to play -music- by running data through his mobo at different rates, that would be different. Until then, i'll sit back and wait for someone to top the ultimate trick:

    Make a Commodore 64 play "A Bicycle Built For Two" by grinding the stepper motor back and forth on the read/write head of a 1541 disk drive. Saw this done back in 1987. :)


    Bowie J. Poag
  • noise just bites. Lately my soundcard (SB64 ISA) has been making strange squeeky noises, and I don't have cheap speakers either, I run my sound through a stereo system. Perhaps I should get that SoundBlaster Live PCI I've been thinking about.

    Another thing, my GSM mobile fscks ups my screen whenever it's in use, and when ever there's a bloody GSM signal floaing about, speakers (any speakers, TV, stereo headphone) make this irritating blip blip blip noise. grrrr


  • Making it be done on FM is magic.
    Not really. The limited edition of the 2.2.10 kernel that was given away with Kellogg's Cornflakes had a special frequency modulation module; it works best when combined with Kellogg's proprietary 'snap crackle pop' sound card. It's only got three channels, and the second one sounds like an old LP, but it's still very effective. The entire musical output of Fatboy Slim can be generated overnight and released as MP3s when you get up in the morning.
  • And here I thought I was the only one on /. old enough to remember Dompier. :)

    I had an Imsai, not an Altair, and remember too well loading some simple programs from the front panel switches. (Let the kids try to figure out what that means.)

    And then there was the ASR-33..........
  • "Judas Priest is Gates"
  • My first exposure to computers was on a high school field trip to the old DEC factory in Maynard MA (in an old textile mill) where they were making early minicomputers - PDP 8's with 12 bit words, Link 8's etc. in 1967. During this trip we were shown a Link 8 with an AM radio sitting on top of the machine playing Greensleeves based on the program running in the machine at the time. This trick is at least 35 years old.
  • Could we make an mp3 "broadcaster" out of this? :) That would make an interesting output plugin for Winamp or Xmms.

  • It seems to me that it would prove useful to investigate the use of this ability to generate coherent signals from a processor as a method of connecting wireless devices. Your Jini laptop could use the processor as a resource and interact as it wished with other Jini. Phone lines could be identified electronically by the phone company, detectable by any technician or competent person with access to tools.

    Perhaps such things will come about. I remember reading an article once about networks of processors with switchable gates that could adapt to their surroundings; as I remember, they communicated through electromagnetic signals - interference, perhaps. Very strange; when they moved the processors, they stopped working. Ah, it was in Discover magazine [...] [208.226.13.177] at one point; I'd recommend reading it with this information in mind; a room could be wired with a network of low-power sensors, for instance.

    Cool.

  • I have heard this done with the CLOWN (500+ node)
    system assembled in Paderborn, Germany on 06th Dec 1998.
    They rather used the speakers, so you could
    listen w/o a radio, but I neverd before heard such an wierd sound.

    Now technically it is a lot simpler than creating
    FM signals, but still is fun to listen to. They used a simple server that send modified pings to the nodes that contained the freq in the timeout field IIRC. A small programm would send rising freq to the nodes by their ip numbers. The way the nodes where layout, you could hear the wave swirling around you when you stepped into the cluster.
  • Making a system play music on an AM radio is a 30-year-old trick. Making it be done on FM is magic.
  • I can't seem to hear anything from my system. Maybe the shielding is good....I'll probably take the case off later....
  • The word "radio" should be inserted somewhere above :)
  • I remember keying (switching?) in 'The fool on the hill' from a Creative Computing mag into my Altair's front panel. I took about an hour, so I would let it play for the rest of the day. My Mom still remembers it playing for hours on end. This was before we got the 88-ACR cassette tape interface so I could save huge efforts like that.

    Now if they could generate a real FM signal and play recognizable music, that'd be something, bonus points for Stereo playback. What I suspect is that the FM reciever is picking up the strong(relatively) AM signal and playing that.
  • Not really. My old 386 happily swamps most of the FM waveband between 99MHz-102MHz. Dead irritating when a few local FM stations with weak transmitters happen to broadcast around there.

    I guess I could get it to play things if I wanted to, but I'd rather listen to Classic FM.

    "Cake or death!" (E. Izzard)
  • I seem to remember people doing this with their Timex Sinclair "computers" back in the 80's.

    What goes around, comes around.

    99 little bugs in the code, 99 bugs in the code,
    fix one bug, compile it again...

  • Quite a few years back we where working on a Video on Demand system which had a Pentium 90 and 128 MB of RAM.

    We developed the software under DOS because the MPEG decoder only had closed source DOS drivers.

    I had written the memory access routines because no DOS extenders supported >64MB.

    Then when I started to run tests to verify my routines, the system started to make these funny chirping sounds. It wasn't loud but definately audible. And there where different tones. I was actually thinking of making the test routine a song, but since the whole project lasted only two months there was no time to play...

    We have never been able to positively identify where the sound came from exactly, but we are pretty sure it was the RAM. It was not the power supply and there was no harddrive in the system.

    When a few years later we had a custom motherboard made we told the manufacturer of this board and they just laughed at us, said it was impossible. Ah well, maybe one day I'll put that system together again... ;)

    Breace
  • mwahaha...

    I wonder, then, what error msgs in Windows sound like when broadcast.. or those infamous Blue Screens of Death.

    hmmmmm..
  • and, i heard, if you play the frequencies from an amd backwards, it says that bill is dead. - - - - - - - - - - - Jacob Rothstein http://www.petitioneer.com/
    ----- --- - - -
  • yeah. i mean, come on. hackers have been doing this forever... I even saw it on tv, so some more of you oughta know about it.

  • Who needs anything else?

    An unlimited amount of free music, much of it better than some junk on the radio today.

    Get a simple cat /dev/urandom going at the same time, and you'll have an endless multimedia experience AT LEAST on par with CBS.
  • Did this on my Sinclair ZX80 (pre-Timex). Wrote a brownian music generator from an ancient Amateur Scientist column (pre-PCs, used spinners on cardboard to generate random within params).

    Geez, I'm making myself feel old.
  • I've heard the video card in an *old* SGI chirp
    when pushing polygons to the screen.

    The video board (framebuffer, rendering engine;
    whatever) was about A2-size and absolutely
    *covered* with ICs.

    We thought it as the heat generated. But it was rather cool, in a way, being able to hear how many things were spinning on the screen.

  • Bill's manic laughter.

  • Vaguely related...

    There were a number of programs on the Apple ][ and C-64 which played music by stepping the drive heads at various frequencies.

    I had one that played In the Hall of the Mountain King which got more and more insane as it went. Kind of a test to see what level of abuse you'd let your drive go through.

    I was used to realigning those damned 1541s anyway.

  • This shows why it is important to keep the lid on computercases. Computers are a big source of radio frequency interference and make the life of radio operators difficult.
    Please put the lid on your computer if it isn't allready there.
  • A system is secure if you have an elephant stomp on it, if you put it inside Mt. Everest, or if you put it in the Mariana Trench :-)

  • Dancing Demon was one of those wonderful Leo Christopherson hacks using packed strings in BASIC. If you're feeling really nostalgic, you can download a TRS-80 emulator and the Dancing Demon program (among others) here: http://www.trs-80.com/ Baudtender
  • I think the solution to all things is "Run rc5des" I'm sure this creates enough random white noise that *no* one will be able to decode the crap coming out off your bus and cpu!

    patofiero

    "Hokey religions and ancient weapons are no
    match for a good blaster at your side, kid"
    - Han Solo
  • There are two scenarios:

    1) Malicious program sending signals from your
    machine. (The scenario you suggest)

    2) Eavesdropping on signals coming from your machine. (The scenario I was thinking of)

    The first insinuates that you *already* have access to the critical data! There has to be easier and more secure ways to send that data then through the generation and leaking of radio frequency signals (watermark the data in a jpg and email it to your yourself?).

    The second scenario, being more likely, involves gathering leaked signals and doing some form of analysis to decipher the internal state of the machine. You could in theory create a clone of the target machine and use it to train the signal analysis software to recognize certains actions by pattern matching?

    ...patofiero turns his head to hear a short burst of low frequency blips...
    "hrm, that sounds like my nfs server dumping core."

    Patofiero.
  • Problems: 1) Recompiled Kernel with XXX configuration. The average signal data taken during a boot sequence might reveal what is in the kerel! 2) Hacked Kernel. It would be very hard to decipher anything if the scheduler didn't follow the *regular* rules for running process'. However, most people run stock kernels and would be succeptable to this... I'm almost tempted to try this out :) 3) What if they aren't running some for of *NIX? We resort to the trivial solution ;) patofiero

  • All we are discussing here is what the military refers to as TEMPEST hazards. Your computer system (particularly the monitor) broadcasts signals in the radio frequency which, given the correct equipment, can be intercepted and interpreted intelligently. We used to have an $18000 286 System when I was in military communications - the only reason it was so expensive (a regular 286 was only $2200 or so) was because the whole thing was lined with lead to prevent TEMPEST emmissions. Like it or not your use of the computer can be monitored completely by someone sitting outside your house or apartment with a directional antenna and the correct equipment in a van.

    Now the fact that someone is affecting their emmissions to play music is another matter that is quite cool. I remember a little program that someone wrote that would play "El Condor Pasa" on my Amiga's floppy drive.

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