Int 21 Fn 11  - DOS 1+ - Find First Matching File Using Fcb                [D]

   AH = 11h
   DS:DX -> unopened FCB (see AH=0Fh), may contain '?' wildcards

Return: AL = status
       00h successful
       [DTA] unopened FCB for first matching file
       FFh no matching filename, or bad FCB

Notes: the type of the returned FCB depends on whether the input FCB was a
     normal or an extended FCB
   the data returned in the DTA is actually the drive number (or extended
     FCB header and drive number) followed by the file's directory entry
     (see below); this format happens to be compatible with an unopened
     FCB
   for extended FCBs with search attribute 08h, the volume label (if any)
     will be returned even if the current directory is not the root dir.
   DOS 3+ also allows the '*' wildcard
   the search FCB must not be modified if AH=12h will be used to continue
     searching; DOS 3.3 has set the following parts of the FCB:
        0Ch    BYTE    ???
        0Dh    WORD    directory entry number of matching file
        0Fh    WORD    cluster number of current directory
        11h  4 BYTEs   ???
        15h    BYTE    drive number (1=A:)
   this function is used by many copy protection schemes to obtain the
     starting cluster of a file

See Also: AH=12h,AH=1Ah,AH=4Eh,INT 2F/AX=111Bh

Format of directory entry:
Offset Size    Description
 00h  8 BYTEs  blank-padded filename
 08h  3 BYTEs  blank-padded file extension
 0Bh   BYTE    attributes
 0Ch 10 BYTEs  reserved
       used by DR-DOS to store file password
 16h   WORD    time of creation or last update (see AX=5700h)
 18h   WORD    date of creation or last update (see AX=5700h)
 1Ah   WORD    starting cluster number
 1Ch   DWORD   file size