#include "dos.h"

void interrupt keytwice();

void interrupt (*prev)();

 

main()

{

//AIM : TSR to print every key pressed twice

      unsigned long far *keyptr;

      keyptr=(unsigned long far*)36;

      prev=(void (interrupt far*)())*keyptr;

      *keyptr=(unsigned long)keytwice;

      keep(0,500);

      return 0;

}

 

void interrupt keytwice()

{

      (*prev)();

      (*prev)();

}