File Control Block (FCB) Structure

               Length
    Offset     (bytes)  Description
    ────────────────────────────────────────────────────────────────────────

    00h        1        Drive identifier  (1=A:)
    01h        8        Filename
    09h        3        File extension
    0Ch        2        Current block no.
    0Eh        2        Record size in bytes, defaults to 80h
    10h        4        File size in bytes
    14h        2        Date
    16h        2        Time
    18h        8        Reserved
    20h        1        Current record no., used for sequential read/write
    21h        4        Random record no., used for random read/write


    An extended File Control Block is used to access files with special
    attributes. An extended File Control Block has three additional
    fields, starting at offset -07h (minus 7), as follows:

    Offset     Length   Description
    ────────────────────────────────────────────────────────────────────────

    -07h       1        Extended FCB flag (always FFh)
    -06h       5        Reserved (zeros)
    -01h       1        File attribute


    Note:     File Control Blocks are a holdover from DOS 1. It is pre-
              ferable to manipulate files using the newer DOS services that
              deal with files via handles. (All file functions above 2Eh
              use handles rather than FCBs.)