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                   FCB - Standard DOS File Control Block

      Offset Size             Description

        -7   byte       if FF this is an extended FCB  +
        -6  5bytes      reserved  +
        -1   byte       file attribute if extended FCB  +
        00   byte       drive number (0 for default drive, 1=A:, 2=B:, ...)
        01  8bytes      filename, left justified with trailing blanks
        09  3bytes      filename extension, left justified w/blanks
        0C   word       current block number relative to beginning of the
                        file, starting with zero
        0E   word       logical record size in bytes
        10   dword      file size in bytes
        14   word       date the file was created or last updated

                |F|E|D|C|B|A|9|8|7|6|5|4|3|2|1|0| 15,14 (Intel reverse order)
                 | | | | | | | | | | | +--------- day 1-31
                 | | | | | | | +---------------- month 1-12
                 +----------------------------- year + 1980

        16   word       time of last write

                |F|E|D|C|B|A|9|8|7|6|5|4|3|2|1|0| 17,16 (Intel reverse order)
                 | | | | | | | | | | | +---------- secs in 2 second increments
                 | | | | | +--------------------- minutes (0-59)
                 +------------------------------ hours (0-23)

        18  8bytes      see below for version specific information  +
        1A   dword      address of device header if character device  +
        20   byte       current relative record number within current BLOCK
        21   dword      relative record number relative to the beginning of
                        the file, starting with zero; high bit omitted if
                        record length is 64 bytes


          DOS 2.x Values for reserved fields at offsets 18h-1Ah       +

      Offset Size             Description
        18   byte       |7|6|5|4|3|2|1|0|
                         | | +------------- unknown
                         | +-------------- 1 = open
                         +--------------- 1 = logical device

        19   word       starting cluster number  +


          DOS 3.x Values for reserved fields at offsets 18h-19h       +

      Offset Size             Description
        18   byte       System File Table (SFT) entry for file  +
        19   byte       attributes  +

                        |7|6|5|4|3|2|1|0|  attributes
                         | | +-------------- unknown
                         +--- share status

                        00 = SHARE not loaded block device
                        01 = SHARE not loaded characted device
                        10 = SHARE loaded, remote file
                        11 = SHARE loaded local file


         DOS 3.x with SHARE, local file reserved offsets 1Ah-1Eh  +

      Offset Size             Description
        1A   word       starting cluster number
        1C   word       offset within SHARE of sharing record
        1E   byte       file attribute


        DOS 3.x with SHARE, remote file reserved offsets 1Ah-1Eh  +

      Offset Size             Description
        1A   word       sector number containing directory entry
        1C   word       last cluster accessed relative to beginning of file
        1E   byte       absolute cluster number of last cluster accessed


             DOS 3.x without SHARE reserved offsets 1Ah-1Fh  +

      Offset Size             Description
        1A   byte       ((device attribute word low byte) & 0Ch) || (open mode)
        1B   word       starting cluster number
        1D   word       sector number containing directory entry
        1F   byte       number of directory entry within sector


      The following are FCB related DOS functions:

        INT 21,F   Open file using FCB
        INT 21,10  Close file using FCB
        INT 21,11  Search for first entry using FCB
        INT 21,12  Search for next entry using FCB
        INT 21,13  Delete file using FCB
        INT 21,14  Sequential read using FCB
        INT 21,15  Sequential write using FCB
        INT 21,16  Create a file using FCB
        INT 21,17  Rename file using FCB
        INT 21,21  Random read using FCB
        INT 21,22  Random write using FCB
        INT 21,23  Get file size using FCB
        INT 21,24  Set relative record field for FCB
        INT 21,27  Random block read using FCB
        INT 21,28  Random block write using FCB
        INT 21,29  Parse filename for FCB


        +  see Bibliography reference to "Undocumented DOS"

        - see   XFCB   INT 21,52