Personal Ancestral File (PAF) used to be a very popular Windows genealogy program although it is now becoming old fashioned. This free program hasn't seen any significant upgrades in years. However, many pople are still loyal users of the program and don't wish to switch to a more modern product. Luckily, PAF works on the latest versions of Windows and now will even work on a Macintosh.
Lorin Lund has written a set of "how to" instructions for the new Macintosh user who wishes to keep the old PAF program. You can read his instructions at http://www.ParowanSoftware.com/PAFonMAC/PAFonMac.html
Actually, there are several ways of running PAF on a Mac but this is the first time I have seen written instructions for the method Lorin uses.