Google is useful here, search serial connect mac pc.

http://www.macwindows.com/peertips.html has some serial ideas.

Many other articles, some with USB converters to serial. Caution: I have not done any of these but hope this helps. By the way, the pin numbering on that last Mini Din 8 drawing link is contrary to custom, I prefer the way Apple uses in its documentation, with pin 5 having the most separation.