Function 4407h          Check Device Output Status

    Checks to see if the device or file is ready for output.

        Entry   AX = 4407h
                BX = Device or file handle

        Return  AL = FFh   Ready
                AL = 00h   Device not ready
                or
                AX = Error code, if CF is set
                     | 01h Invalid function
                     | 05h Access denied
                     | 06h Invalid handle

    Note
    For an output file, this function always returns AL = FFh (ready),
    even if the disk is full or there is no disk in the drive.

    
    Example

        mov     bx,StdPrn
        mov     ax,4407h
        int     21h
        jc      @@error
        cmp     al,0ffh
        jnz     @@PRN_not_ready
        ;...