This version of ORTEP-III for Mac OS X only works inside its unix environment. This is accessed from the Terminal application found in the Utilities folder inside the OS X Applications folder. Knowledge of unix is required. The input files must have unix line endings rather than the normal Mac line ends. To set up: 1. From the Mac OS X GUI, copy the file AquaTerm to the OS X Applications folder. 2. As root in the unix environment in a Terminal window, copy /Volumes/ORTEP-III_for_Mac_OS_X/ortep to a suitable place, e.g. /bin or /usr/bin 3. As root in the unix environment in a Terminal window, copy /Volumes/ORTEP-III_for_Mac_OS_X/grfont.dat to a suitable place, e.g. /etc 4. While logged into your Mac in your usual manner (not root), run the Terminal application and edit the file .bash_profile (which may not exist) in your unix login directory. Add the following two lines: PGPLOT_DIR=/etc; export PGPLOT_DIR PGPLOT_DEV=/AQT; export PGPLOT_DEV The first line indicates the path where the grfont.dat file was placed. 5. Quit the Terminal application. To run: 1. Start the Terminal application. 2. Change to the directory that contains the ortep input file. 3. Type ortep