From what info I've found, it seems a pc parport has a max speed of ~2meg /sec ?
So transmission on medium wave, to ~160 meters should be possible ?
With antenna than possibly a small wire, I would think transmission range would only be a few feet at best ?
However, I've also found info to suggest that trying to program the port under any non real time os is going to yield only a few hundred Khz at best.
If so, I'm thinking maybe a custom boot program that might be the solution ?
I've found a few examples of RF / AM, FM transmitting using microcontrollers, and I then wondered if a PC could do something similar with either the parallel, USB or serial ports for either medium wave or ham frequencies.
Serial looks too slow, and USB not doable without some kind of USB dev board / custom device, so that leaves the parallel port.