Quote: Originally Posted by
Woofnstuff 
That is the easiest.
If you want to try and make something yourself, then you can use the parallel port if you actually have one. A USB-->LPT1 will not work.
Also keep in mind that during bootup, both serial DB9 connections and parallel LPT1 connections can and will shoot out random bit sequences until they are loaded. This means if you have just a very simple non-logic circuit on it, you run the risk of mucking it up when the pc boots, so you should have some protection for that. Something like a start communication sequence and the probability of the random bursts equalling that would be lower the longer/more bits the code is.
http://www.epanorama.net/circuits/parallel_output.html