System Bus Radio: Transmits AM radio on computers without transmitting hardware
I debugged a boot issue on the Apple Newton this way. The latest flash image was a brick on production hardware (no available LEDs, GPIOs, etc.) but not on development hardware. But I <i>could</i> flash a new OS image.<p>So I wrote some small loops that did different stuff on the bus (so that they sounded different) and salted the boot path with them, then listened in on my portable AM radio. Found the problem inside of an hour by moving the loops further down the path.<p>There were probably other ways to do this (could have coaxed a hardware tech in the lab to solder in a GPIO), but this way was more fun. :-)