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INT 27h (39)             Terminate and Stay Resident

    Terminates a program and leaves a specified portion installed in
    memory.

       On entry:      CS         Segment of PSP
                      DX         Address at which next program may be loaded
                                 (i.e., highest address to stay resident + 1)

  --------------------------------------------------------------------------

       Note:          Interrupt 27h is the original (i.e. DOS 1.x) method
                      of creating a TSR program. Unlike its DOS 2.0-and-
                      later counterpart, Interrupt 21h, Function 31h, it
                      does not allow you to pass a return code. And the
                      amount of memory that may kept resident is limited
                      to 64K.

                      Use INT 21h function 31h to keep EXE programs
                      resident in memory.

                      Files are not closed by Interrupt 27h.