The requested instrumentation will enhance the graphics facilities in the Markey Macromolecular Crystallography Center at Purdue University. This equipment will be used for modeling biological macromolecules whose structures have been determined by means of X-ray crystallography, electron microscopy and nuclear magnetic resonance spectroscopy. With ten faculty (involving 2 research scientists, 40 postdoctoral fellows, 27 graduate students) working actively on a wide variety of structures, such as viruses, enzymes, antibodies, various proteins and nucleic acids, the present system of three computer graphics systems has become completely inadequate. To alleviate the situation, it is proposed to purchase two Evans an Sutherland ESV 20/33 graphics workstations sustained by a VAX 4000 computer with 4.4 GB of disk storage, plus equipment and software for the Network File System. This is also being supplemented by one further ESV 20/33 graphics system which has already been ordered to ease the current crisis.