The DS1642 is an RTC + NVRAM
The information is in centain memory locations in bcd format:



Ok , so i made a simple program to display the
minutes :

#include <reg51.h>

xdata minutes _at_ 0x07FA;    //this is the memory location containing minutes
xdata control _at_ 0x07F8;    //this is the control reg

void main()
{

while(1)
{
    control = 0x40;           //set the read bit
    putchar(13);putchar(10);putchar('m');putchar('=');  //eye candy
    punchar(minutes);
    control = 0x00;           //reset the read bit
    delay(100);
}
}

The minutes counter should advance after every minute , but it doesnt.
Whats wrong with the prog?