Function 49h (73)        Free Allocated Memory

    Releases memory that was allocated via Function 48h.

       On entry:      AH         49h
                      ES         Segment address of memory to be released

       Returns:       AX         Error code, if CF is set

       Error codes:   7          Memory control blocks destroyed
                      9          Invalid memory block address

                      Call Function 59h for extended error code information
                      (DOS 3.0 and above).

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    This function returns to DOS the memory that was allocated by means of
    Function 48h. ES points to the segment address of the block that is
    being returned; this is the same value that Function 48h returned in
    AX.