DS12887 VRT The Valid RAM and Time(VRT)bit is set to the 1 state by Dallas Semiconductor prior to shipment.This bit is not writable and should always be a I when read.If a 0 is ever present,an exhausted internal lithium energy source is indicated and both the contents of the RTC data and RAM data are questionable.This bit is unaffected by RESET BIT 6 THROUGH BIT 0 The remaining bits of Register D are not usable.They cannot be written and,when read,they will always read 0. 12of19DS12887 12 of 19 VRT The Valid RAM and Time (VRT) bit is set to the 1 state by Dallas Semiconductor prior to shipment. This bit is not writable and should always be a 1 when read. If a 0 is ever present, an exhausted internal lithium energy source is indicated and both the contents of the RTC data and RAM data are questionable. This bit is unaffected by RESET . BIT 6 THROUGH BIT 0 The remaining bits of Register D are not usable. They cannot be written and, when read, they will always read 0