C Programming (Turbo C++ Compiler) - Terminate and Stay Resident Program (TSR) Timer Clock Sample

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I have given here a sample program for TSR which stands for Terminate and Stay Resident. It is easy to implement but you need to know about interrupt service routines and their functions.

Timer.EXE -i option will install the timer.
Timer.EXE -u option will uninstall the timer.

Source Code

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#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <dos.h>

#include <conio.h>

#include <bios.h>

 

#define INTR 0X1C

 

#ifdef __cplusplus

    #define __CPPARGS ...

#else

    #define __CPPARGS

#endif

 

char far *scr=(char far*)0xB0008000L;

 

void interrupt ( *oldhandler)(__CPPARGS);

 

int count=0;

 

char hbuf[6];

char mbuf[6];

char sbuf[6];

struct  time t;

 

void interrupt handler(__CPPARGS)

{

      char far *p = 0;

      gettime(&t);

      hbuf[0] = '0' + t.ti_hour / 10;

      hbuf[1] = '0' + t.ti_hour % 10;

      mbuf[0] = '0' + t.ti_min / 10;

      mbuf[1] = '0' + t.ti_min % 10;

      sbuf[0] = '0' + t.ti_sec / 10;

      sbuf[1] = '0' + t.ti_sec % 10;

 

      p = scr;

 

      *p++ = hbuf[0];

      *p++ = 0x4f;

      *p++ = hbuf[1];

      *p++ = 0x4f;

      *p++ = ':';

      *p++ = 0x4f;

 

 

      *p++ = mbuf[0];

      *p++ = 0x4f;

      *p++ = mbuf[1];

      *p++ = 0x4f;

      *p++ = ':';

      *p++ = 0x4f;

 

      *p++ = sbuf[0];

      *p++ = 0x4f;

      *p++ = sbuf[1];

      *p++ = 0x4f;

 

      oldhandler();

}

 

 

int main(int argc, char *argv[])

{

      if(argc <= 1)

      {

            printf("Syntax: Timer -I (for Install)\n");

            printf("Syntax: Timer -U (for Uninstall)\n");

            return 0;

      }

      if(argv[1][1] == 'I' || argv[1][1] == 'i')

      {

            printf("Installing...\n");

            oldhandler = getvect(INTR);

            setvect(INTR, handler);

            setvect(32, oldhandler);

            printf("Done\n");

      }

      else

      {

            printf("Uninstalling...\n");

            oldhandler = getvect(32);

            setvect(INTR, oldhandler);

            printf("Done\n");

      } 

   return 0;

}

 

Click here to download the source code and .EXE application

Output

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