The DS12B887 Real Time Clock plus RAM is designed to be a direct replacement for the DS1287A or DS12887A. The DS12B887 is identical in form, fit, and function to the DS1287A or DS12887A, with the exception of RCLR, and has an additional 64 bytes of general purpose RAM. Access to this additional RAM space is determined by the logic level presented on AD6 during the address portion of an access cycle. A lithium energy source, quartz crystal, and write-protection circuitry are