AH = 12h DS:DX = pointer to unopened FCB returned from INT 21,11 or INT 21,12 on return: AL = 00 if file found = FF if file not found - finds next matching file after calls to INT 21,11 and INT 21,12 - FCB should be the same across calls to INT 21,11 and 12 - after successful call DTA holds an unopened FCB/XFCB for the requested file. Using any of the other FCB functions destroys this DTA copy of the FCB/XFCB