Root directory
Table
|GraphicDIR Δoffset
fat16_directory struct size
FirstRootDirSecNum
BPB_ResvdSecCnt + (BPB_NumFATs * BPB_FATSz16)
The dot entry is a directory that points to itself.
The dotdot entry points to the starting cluster of the parent of this directory (which is 0 if this directories parent is the root directory).