In the early 80s, I knew a kid named Marcus whose father had a terminal with an acoustically coupled modem that he used to connect to the mainframe at his office. He let us use the terminal to dial up and play a game called Dungeon, which was about a half-step above the text-based computer games of the time because it presented you with a primitive graphical representation of where you were:
In this case, you (X) are in a room with doors to the North and East, and there's a monster (M) in there with you. You'd move around by typing things like GO DOOR NORTH or ATTACK and so on. Marcus updated a hand-drawn map on graph paper as we went through the dungeon, because you could only see one room at a time.
The cool thing about the acoustically coupled modem was that if you knocked it or jumped around on the floor, it would pick up the sounds and spew ASCII garbage like 
across the screen. If you pulled the handset out of the coupler and yelled into it, you'd fill up the screen before the mainframe dropped the carrier.
The same principles, apparently, were used to hack the iPod's firmware. Nils Schneider basically made the iPod squawk out its firmware secrets by turning a piezoelectric element within the unit into a speaker, recording the output, and turning the acoustic data back into digital data--just like the modem.
Seth David Schoen at Vitanuova writes,
Somehow this reminds me of the scene in William Gibson's "Johnny Mnemonic" in which Johnny is made to recite (for three hours) a memorized computer program to which he has no conscious access. "And then it all faded to cool gray static and an endless tone poem in the artificial language. I sat and sang dead Ralfi's stolen program for three hours." In the story, the program in question is a misappropriated secret; here, despite the interesting aesthetic parallel, I think Schneider's purpose in studying the iPod's firmware is perfectly proper.
Mr. Schoen goes on to outline the virtues of this über-creative approach, and I think he's right. The technique appeals to the kid in me... the one that used to jump around just to watch ASCII fly across the screen.
[Via BoingBoing.]
