Get your own Prolog
The prolog implementation that we are using in class is called SWI-Prolog. It is free and there are versions for Linux, Windows (95/98/ME and NT/2000/XP), and MacOS X, which you can download from the SWI Prolog web site.
For Mac users who don't have MacOS 10, there is Open Prolog (for MacOS 7.5.5 and later). It's also free and you can download it from the Open Prolog web site. It comes with a small tutorial on how to use it which tells you what to do to write, load and query knowledge bases.
There are other prolog implementations which are free or very cheap for students. The following two web-sites provide lists which look quite comprehensive: