The ribbons software package is copyrighted by the author and licensed through the UAB Center for Macromolecular Crystallography (CMC). The CMC's NASA grant encourages the commercialization of our work. The executable version ribbons 2.6, used in examples section, is free to the academic crystallographer. Please consult our web site at:
http://sgce.cbse.uab.edu/ribbons
Versions now exist for several UNIX workstations. We plan to port ribbons to the PC, MicroSoft having chosen OpenGL as its 3D graphics standard. (RASMOL(42) is a nice free program that already supports raster graphics on workstations and PC's.)
We thank Susan Baum for editorial help, Yang Zi for technical assistance, and NASA for support.