Create temporary file (INT 21h, 5Ah)

        Entry:
          AH = 5Ah
          DS:DX = pointer to ASCIZ directory path name
          CX = file attribute
        Return:
          CF = 1 if error
                     AX = Error Code if any
          DS:DX = path name

        Note: The file created is not truly "temporary".  It MUST be
              removed by the user.
              The file is sure to be unique, that is, no other files will
              be erased or altered.