Function 12h (18)        Search for Next Matching File, using FCBs

    Searches the current directory for next matching filename, following a
    Function 11h call or a previous Function 12h call.

       On entry:      AH         12h
                      DS:DX      Pointer to the unopened FCB specified in
                      a previous Function 11h or Function 12h

       Returns:       AL         00h       If another match found
                                 FFh       If no match found

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       Warning:       The information needed by Function 12h is destroyed
                      by any operation on the file using the FCB created
                      via Function 11h. Therefore, if you want to search
                      for several files and also do I/O on them, you must
                      save the search information that is stored in the
                      FCB.