#include <dos.h>
#include <stdio.h>
#include <conio.h>

#define IOBASE          0x300
#define DIO             IOBASE + 0

#define dio_value(i)    outportb(DIO,(unsigned char)i<<4);

void main(void)
{
  int c;

  do {
    printf(" Input the digital out:");
    scanf("%d",&c);
    dio_value( (unsigned char) (c & 0x0f)<< 4);
  } while(c<16);
}