Downloading a movie from a sugar cube-sized crystal may no longer be the stuff of sci-fi:  IBM's five-year old holographic data storage system (HDSS) program is advancing toward the compact storage of BILLIONS of bytes of rapidly-accessible information. Capable of holding more than one magnitude of the information of today's largest magnetic hard disk drives, holographic storage can also input and retrieve data considerably faster than current storage methods, making it a potentially valuable technology in such areas as aviation, computing, image processing and telecommunications.