XFCB - Extended DOS File Control Block

     Offset Size		Description

	00   byte   flag containing FF if this is an extended FCB
	01  5bytes  reserved
	06   byte   directory attribute byte	(see FILE ATTRIBUTE)
	07   byte   drive number (0 for default drive, 1 = A:, 2 = B:)
	08  8bytes  filename, left justified with trailing blanks
	16  3bytes  filename extension, left justified w/blanks
	19   word   current block number relative to file start (0 based)
	21   word   logical record size in bytes
	23   dword  file size in bytes
	27   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│ 21,20
		 │ │ │ │ │ │ │ │ │ │ │ └─┴─┴─┴─┴─ day 1-31
		 │ │ │ │ │ │ │ └─┴─┴─┴────────── month 1-12
		 └─┴─┴─┴─┴─┴─┴───────────────── year + 1980

	29 16bytes  reserved for system use
	39   byte   relative record number within current BLOCK
	40  4bytes  relative record number from start of file (0 based)