A small Example Program for clock using internal Timer1 in 89s52

i have calculated earlier that it takes the 8051, 1/20th of a second to count from 0 to 46,079. However, the TFx flag is set when the timer overflows back to 0. Thus, if we want to use the TFx flag to indicate when 1/20th of a second has passed we must set the timer initially to 65536 less 46079, or 19,457.

If we set the timer to 19,457, 1/20th of a second later the timer will overflow. Thus we come up with the following code to execute a pause of 1/20th of a second:

TH0=0x076;High byte of 19,457 (76 * 256 = 19,456)
TL0=0x001;Low byte of 19,457 (19,456 + 1 = 19,457)

#include(stdio.h)
#include(at89c51xd2.h)
void delay(void);

void main()
{ int j=0,s=0,m=0,h=0;
SCON = 0x50; /* SCON: mode 1, 8-bit UART, enable rcvr */
TMOD |= 0x20; /* TMOD: timer 1, mode 2, 8-bit reload */
TH1 = 0x076; /* TH1: reload value */
TL1 = 0x001;
TR1 = 1; /* TR1: timer 1 run */
TI = 1;

while(1)
{
if(TF1==1)
j++;
if(j==20)
{
s++;
if(s==60)
{
s=0;
m++;
if(m==60)
{
h++;
m=0;
}
}
printf("the time is %d:%d:%d\n",h,m,s);
j=0;
}
}
}


void delay(void)
{
long int i;
for(i=0;i<50000;i++)
{
;
}}