5 ms·

While I don't know if this is really true, but there was a time when chips like the 8080 ran at a speed that was close to AM frequencies. Programmers figured ou

While I don't know if this is really true, but there was a time when chips like the 8080 ran at a speed that was close to AM frequencies. Programmers figured out that certain patterns produced sounds on their radio. So they would insert garbage code that accessed the address bus at the right speeds. Perhaps this is something along those lines?

westmeal 3y ago
I have an old thinkpad x200 that I can hear operating over an AM radio close enough to the laptop but I have a feeling I'm hearing something else besides the CPU because the CPU would run too fast... right?
duskwuff 3y ago
I think you've misinterpreted the question pretty wildly. The code in question is in the game as text displayed on screen, not as part of the executable. Besides, IBM PC-compatible systems already had a reliable way of making basic sounds - the PC speaker. There was no need for the techniques you're describing on that platform.
- notfish 3y ago
  I think you’ve misunderstood the personality of hackers if you think they would make chips play sounds via radio because it was useful
  - colechristensen 3y ago
    I saw demos of this at either blackhat or defcon, various methods to exfiltrate data by bitbanging pins, running garbage code, or otherwise triggering hardware or peripherals to generate unintended radio signals to be picked up at a distance. I’m pretty sure I’ve heard of old games doing this for fun too.
    - fragmede 3y ago
      Van eck phreaking is some crazy stuff!
- gerdesj 3y ago
  Where in the article does it say "the code in question ... is displayed on screen"? I've read it a few times (half-heartedly) and then just to be sure (quite a few glasses of wine consumed already) I did a search for the word "screen" - nope, but not exactly conclusive. There are several theories espoused but one comment is: "In a brief email conversation with Al Lowe ... he probably used the COMMAND.COM file as the basis for this code ..." Your assertion about "reliable way of making basic sounds" is sort of true, if you ignore the shonky hardware that used to and get shipped as a "speaker". It's better nowadays and largely an anachronism. Back in the day you'd wedge a Soundblaster into an ISA slot along with some reasonable speakers or really good headphones and job done. Your parent may be thinking of the silly games that used to be played with big old Winchester discs on big IDM gear and the like.
  - jerf 3y ago
    "Where in the article does it say "the code in question ... is displayed on screen"?" Nowhere. It is shown in the animation posted in the article, which you may have not noticed was animated if your eyes jumped over it quickly enough.
    - deleted 3y ago
      [deleted]
  - bitwize 3y ago
    Somewhere between the Sound Blaster and using RF leakage in the AM band to generate sound was the Covox Speech Thing, which used the pins from your parallel port and a resistor ladder to generate PCM sound. You could solder one together yourself. Some games supported it, and Disney marketed an improved version with a built-in speaker and powered amplifier as the Disney Sound Source.
  - duskwuff 3y ago
    > Where in the article does it say "the code in question ... is displayed on screen"? As someone else mentioned, it shows up in the GIF animation, about 45 seconds in, as a sequence of text boxes. https://i.stack.imgur.com/8Aznd.gif https://i.stack.imgur.com/8Aznd.gif > Your assertion about "reliable way of making basic sounds" is sort of true, if you ignore the shonky hardware that used to and get shipped as a "speaker". On the IBM PC, one of the channels on the PIT (programmable interval timer) was hooked up to a speaker. It didn't sound great, but it could at least make simple tones on its own, and even music, without sucking up too much CPU time: https://www.youtube.com/watch?v=1IOL4q5tDDQ https://www.youtube.com/watch?v=1IOL4q5tDDQ The Apple II had it much worse. It had a built-in speaker as well, but no timers -- the speaker was connected directly to the memory address $C030, such that performing a read or write operation on that address would toggle the state of the speaker (on/off). Playing a tone required the CPU to hit that address in an appropriately sized loop; since the CPU wasn't particularly fast to begin with, it was nearly impossible to play audio while anything else was going on.
dtgriscom 3y ago
Just last week I spent a few hours using an AM radio to better understand what a locked-up i.MX7 processor was doing. (Unsuccessfully, but it was fun trying.)
- SomeoneFromCA 3y ago
  You may try FM too. I used this technique with AVRs. It was midly useful, as reading from eeprom produced distinct sound.
titzer 3y ago
In college I had a PC with a 100Mhz bus. One day I was defragging the hard disk--as one did in those days--and by chance had the PC case cover off and also the FM radio on. As I swept past 100Mhz I picked up the unmistakable KKSSHH CHKS CHKS CHKS coming from the data going over the bus. For a minute or two I thought the NSA bugged me.
- anthk 3y ago
  Try compiling and running tempest for Eliza if you have a nearby linux/bsd machine.
- mjevans 3y ago
  Wow... that explains 90mhz and 133mhz chips as targets and bases for front side busses.
- WalterBright 3y ago
  > in college At Caltech some students would see how bright an LED could get if you immersed it in a liquid nitrogen bath. There was always something fun going on.

westmeal 3y ago

I have an old thinkpad x200 that I can hear operating over an AM radio close enough to the laptop but I have a feeling I'm hearing something else besides the CPU because the CPU would run too fast... right?

duskwuff 3y ago

I think you've misinterpreted the question pretty wildly. The code in question is in the game as text displayed on screen, not as part of the executable. Besides, IBM PC-compatible systems already had a reliable way of making basic sounds - the PC speaker. There was no need for the techniques you're describing on that platform.

notfish 3y ago
I think you’ve misunderstood the personality of hackers if you think they would make chips play sounds via radio because it was useful
- colechristensen 3y ago
  I saw demos of this at either blackhat or defcon, various methods to exfiltrate data by bitbanging pins, running garbage code, or otherwise triggering hardware or peripherals to generate unintended radio signals to be picked up at a distance. I’m pretty sure I’ve heard of old games doing this for fun too.
  - fragmede 3y ago
    Van eck phreaking is some crazy stuff!
gerdesj 3y ago
Where in the article does it say "the code in question ... is displayed on screen"? I've read it a few times (half-heartedly) and then just to be sure (quite a few glasses of wine consumed already) I did a search for the word "screen" - nope, but not exactly conclusive. There are several theories espoused but one comment is: "In a brief email conversation with Al Lowe ... he probably used the COMMAND.COM file as the basis for this code ..." Your assertion about "reliable way of making basic sounds" is sort of true, if you ignore the shonky hardware that used to and get shipped as a "speaker". It's better nowadays and largely an anachronism. Back in the day you'd wedge a Soundblaster into an ISA slot along with some reasonable speakers or really good headphones and job done. Your parent may be thinking of the silly games that used to be played with big old Winchester discs on big IDM gear and the like.
- jerf 3y ago
  "Where in the article does it say "the code in question ... is displayed on screen"?" Nowhere. It is shown in the animation posted in the article, which you may have not noticed was animated if your eyes jumped over it quickly enough.
  - deleted 3y ago
    [deleted]
- bitwize 3y ago
  Somewhere between the Sound Blaster and using RF leakage in the AM band to generate sound was the Covox Speech Thing, which used the pins from your parallel port and a resistor ladder to generate PCM sound. You could solder one together yourself. Some games supported it, and Disney marketed an improved version with a built-in speaker and powered amplifier as the Disney Sound Source.
- duskwuff 3y ago
  > Where in the article does it say "the code in question ... is displayed on screen"? As someone else mentioned, it shows up in the GIF animation, about 45 seconds in, as a sequence of text boxes. https://i.stack.imgur.com/8Aznd.gif https://i.stack.imgur.com/8Aznd.gif > Your assertion about "reliable way of making basic sounds" is sort of true, if you ignore the shonky hardware that used to and get shipped as a "speaker". On the IBM PC, one of the channels on the PIT (programmable interval timer) was hooked up to a speaker. It didn't sound great, but it could at least make simple tones on its own, and even music, without sucking up too much CPU time: https://www.youtube.com/watch?v=1IOL4q5tDDQ https://www.youtube.com/watch?v=1IOL4q5tDDQ The Apple II had it much worse. It had a built-in speaker as well, but no timers -- the speaker was connected directly to the memory address $C030, such that performing a read or write operation on that address would toggle the state of the speaker (on/off). Playing a tone required the CPU to hit that address in an appropriately sized loop; since the CPU wasn't particularly fast to begin with, it was nearly impossible to play audio while anything else was going on.

dtgriscom 3y ago

Just last week I spent a few hours using an AM radio to better understand what a locked-up i.MX7 processor was doing. (Unsuccessfully, but it was fun trying.)

SomeoneFromCA 3y ago
You may try FM too. I used this technique with AVRs. It was midly useful, as reading from eeprom produced distinct sound.

titzer 3y ago

In college I had a PC with a 100Mhz bus. One day I was defragging the hard disk--as one did in those days--and by chance had the PC case cover off and also the FM radio on. As I swept past 100Mhz I picked up the unmistakable KKSSHH CHKS CHKS CHKS coming from the data going over the bus. For a minute or two I thought the NSA bugged me.

anthk 3y ago
Try compiling and running tempest for Eliza if you have a nearby linux/bsd machine.
mjevans 3y ago
Wow... that explains 90mhz and 133mhz chips as targets and bases for front side busses.
WalterBright 3y ago
> in college At Caltech some students would see how bright an LED could get if you immersed it in a liquid nitrogen bath. There was always something fun going on.