Listing 2 (PAR_COMM.H)

/*Description: Include file for PAR_COMM.C
  Portability: MS-DOS Microsoft C or Borland C */

#if !defined ( PAR_COMM_DEFINED )
   
   unsigned correct_bios_status( unsigned Status );
   unsigned correct_port_status( unsigned Status );
   unsigned get_prn_port( unsigned PrnNum );
   unsigned in_bios_nibble( unsigned PrnNum );
   unsigned in_bios_status( unsigned PrnNum );
   unsigned in_port_nibble( unsigned PrnPort );
  unsigned in_port_status( unsigned PrnPort );
  unsigned invert_bit( unsigned Val, unsigned Bit );
  
  #if !defined ( LPT1 )
     #define LPT1 0
     #define LPT2 1
     #define LPT3 2
     #define LPT4 3
  #endif
  
  #define PAR_COMM_DEFINED

#endif

/* End of File */