SlideStore is an improved optical memory concept that uses metalized glass slides 4 by 4 inches by 60 mils thick as the recording medium. Digital information. is recorded onto these glass slides by ablation of the metal film with a laser beam. Each slide will hold 2.9 x l09 user bits. The information recorded in the present system is digitized pictorial information that has been run-length encoded to increase the packing density. Each slide will hold approximately 12,000 correspondence type documents. A SlideStore is configured to hold 2000 slides in one read write module. The data rate is 5 megabits per second and the error rate is less than 1 in 1011 bits. The engineering prototype is now undergoing systems tests.