INT 21,56 - Rename File
AH = 56h DS:DX = pointer to old ASCIIZ path/filename ES:DI = pointer to new ASCIIZ path/filename on return: AX = error code if CF set (see DOS ERROR CODES) - supports full pathnames and allows renaming files across directories and in DOS 3.x allows renaming subdirectories - does not support use of wildcards unless invoked from via INT 21,5D in which case error code 12h is returned - unpredictable result may occur if an opened file is renamed - see Bibliography reference to "Undocumented DOS"