Hacking x86 Architecture to Transmit RF
A small hack using the maximum frequency of an x86 hardware timer in order to generate a 597kHz carrier signal which can be modulated in software. The resulting interference can be picked up on an MW radio.
Routine written to the boot sector of the floppy. The Programmable Interval (PIT) is a device used on most x86 computers for interrupts and for setting a square wave frequency for the internal buzzer (or speaker/audio out).
By setting it to its maximum frequency (1.193182 MHz / 2 = 596.591kHz) and turning on/off using timed delay loops, we can create an AM radio signal through the headphone jack. A length of wire connected to this acts as an antenna - in this instance a longer length increases the range. 597kHz falls in the medium wave band and can be received using a normal MW radio.
Inspired in part by the use of AM EMI to make music on the old Altair 8800