The parallel device operates like the other Amiga devices.  To use it, you
must first open the parallel device, then send I/O requests to it, and
then close it when finished.  See "introduction to amiga system devices"
chapter for general information on device usage.

The I/O request used by the parallel device is called IOExtPar.

    struct   IOExtPar
        {
        struct  IOStdReq IOPar;
        ULONG   io_PExtFlags;   /* additional parallel flags */
        UBYTE   io_Status;      /* status of parallel port and registers */
        UBYTE   io_ParFlags;    /* parallel device flags */
        struct  IOPArray io_PTermArray; /* termination character array */
        };

See the include file devices/parallel.h for the complete structure
definition.

 opening the parallel device                 writing to the parallel device 
 reading from the parallel device    closing the parallel device