#include <dos.h>
#define VIDEO 0x10      //video interrupt
#define COLS 80         //screen width
#define ROWS 25         //screen rows
#define PRINTER 0x17    //BIOS printer interrupt
#define LPT1 0x00       //LPT1. your first printer
#define EJECT 0x0c      //Eject page printer command

void cls(void);
void locate(int col,int row);
void eject(void);
void prnchar(char c);
void prnstring(char *string);

void cls(void)
{
 union REGS regs;

 regs.h.ah=0x06;        //func 6, scroll window
 regs.h.al=0x00;        //clear screen
 regs.h.bh=0x07;        //make screen "blank"
 regs.h.ch=0x00;        //upper left row
 regs.h.cl=0x00;        //upper left column
 regs.h.dh=ROWS-1;      //lower right row
 regs.h.dl=COLS-1;      //lower right column
 int86(VIDEO,&regs,&regs);

 locate(0,0);           //"Home" the cursor
}

void locate(int col,int row)
{
 union REGS regs;

 regs.h.ah=0x02;        //vid func 2, move cursor
 regs.h.bh=0x00;        //video screen (always 0)
 regs.h.dh=row;         //cursor's row pos
 regs.h.dl=col;         //cursor's col pos
 int86(VIDEO,&regs,&regs);
}

void eject(void)
{
 prnchar(EJECT);
}

void prnchar(char c)
{
 union REGS regs;

 regs.h.ah=0x00;        //print character function
 regs.h.al=c;           //character to print
 regs.x.dx=LPT1;        //printer port to print to
 int86(PRINTER,&regs,&regs);
}

void prnstring(char *string)
{
 while(*string) //while there's a char to print
      prnchar(*string++);        //print it and increment
}