00D RT - Status Register D

          1xxx xxxx  Valid RAM
                       This read-only bit monitors the power-sence pin. A
                       low state of this pin indicates a loss of power to
                       the real-time clock (dead-battery). When set to 1,
                       this bit indicates that the real-time clock has
                       power. When set to 0, it indicates that the real-
                       time clock has lost power.
          x111 1111  Reserved