INT 2Fh (47)             Multiplex Interrupt (APPEND)               ≥ DOS 3.1

    Reports whether the resident part of APPEND is installed.

       On entry:      AH         B7h
                      AL         00h

       Returns:       AL         00h     Not installed, okay to install
                                 01h     Not installed, not okay to install
                                 FFh     Installed