#include   //Define 8051 Registers

void serial(void); //Serial Communication Register

void DelayMs(unsigned int);    //Delay Function

unsigned int i,j;

unsigned char b[25],d;

//---------------------------

//           Main Program

//---------------------------

void main()

{

    EA=1;            //Enable All Interrupt

    ES=1;            //Enable Serial Port Interrupt

    serial();        //Serial Communication

         while(1);    //Loop Forever

}

//------------------------------------------

//       Serial Communication Register Initialisation

//------------------------------------------

void serial(void)

{

    TMOD=0X20;       //Timer1, Mode2

    SCON=0X50;       //Serial Mode1, Receive Enable

    TH1=0XFD;        //Baud Rate 9600bps

    TR1=1;           //Timer1 ON

}

//-----------------------------------------

//       Serial Interrupt Function

//-----------------------------------------

void serin (void) interrupt 4  //Serial Port Interrupt

{

    if(RI==1) //Receive Interrupt Gets Enabled

    {            //after Stop Bit get Received

         d=SBUF; //Serial Buffer value moved to a variable

         b[j]=d;                                                   

         SBUF=b[j];

         DelayMs(20); //Delay Function

         j++;

    }

    SCON=0X50;   //Initialising Receive and Transmit Interrupt

}

//---------------------------------

//               Delay Function

//---------------------------------

void DelayMs(unsigned int k)

{

    unsigned int i;

    for(i=0;i<=k;i++);

}

#include<string.h>

int a,b,ans;

char rec[4];

void main()  

{   

a=80;

b=40;

ans=a+b;

sprintf(rec, "%d", ans);

TMOD=0x20;                                //Choosing Timer mode   

TH1=0xFD;                                   //Selecting Baud Rate   

SCON=0x50;                               //Serial mode selection   

TR1=1;   

IE=0x90;                                      //Enabling Serial Interrupt   

while(1);   

}

void ser_intr(void)interrupt 4        //Subroutine for Interrupt 

{

IE=0x00;

short int i;

for(i=0;i<=2;i++)                      //Transmitting data

{

SBUF=rec[i];

while(TI==0);

TI=0;

}

IE=0x90;

}