The chdir function changes the default directory. The change can
    be permanent or temporary. Permanent means that the new directory
    remains as the default directory after the image exits. Temporary
    means that on image exit, the default is set to whatever it was
    before the execution of the image.

    There are two ways of making the change permanent:

    o  Call chdir from USER mode with the second argument set to 1.

    o  Call chdir from SUPERVISOR or EXECUTIVE mode, regardless of
       the value of the second argument.

    Otherwise, the change is temporary.