go for the links
http://www.engineersgarage.com/microcontroller/8051projects/digital-clock-rtc-12c887-AT89C51
http://www.engineersgarage.com/microcontroller/8051projects/interface-rtc-12c887-AT89C51
http://www.engineersgarage.com/real-time-clock
http://www.engineersgarage.com/microcontroller/8051projects/alarm-clock-rtc-12c887-AT89C51