(C)hange Directory

            This command allows the caller to move within the hard (or
            other) drive, using DOS rules for doing so, or by a SysOp
            provided menu. By pressing (F)ile Directory while the caller
            is in a given directory, he sees the available subdirectories.
            The subdirectories are enclosed in [] brackets.  The caller may
            neither enter a drive specifier here nor change to the directory
            containing the MEGAHOST run-time files.