Function 3Bh (59)        Change Directory (CHDIR)

    Change the current directory.

       On entry:      AH         3Bh
                      DS:DX      Pointer to name of new default directory
                                 (ASCIIZ string)

       Returns:       AX         Error code, if CF is set

       Error Codes:   3          Path not found

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

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    Function 3Bh (CHDIR) changes the current directory to the directory
    whose path is specified in the ASCIIZ string at address DS:DX; the
    string length is limited to 64 characters.  The path name may include
    a drive letter.