0x0000 - 0x03ff : interrupt vector table
0x0400 - 0x04ff : bios data area
0x0500 - 0x05ff : global info
  0x00 dword : fat pointer
  0x04 dword : root directory pointer
  0x08 word  : usable memory from 0 to 1MiB in kiB
  0x0a word  : usable memory from 1MiB to 16MiB in kiB
  0x0c dword : bootloader:
                 lower word: low memory usage by bootloader in kiB,
                 upper word: kernel image length in kiB
               kernel:
                 file handle array pointer
  0x10 dword : process array pointer
  0x14 word  : usable memory from 16MiB up in 64s of kiB
0x0600 - 0x6fff : not assigned

0x7c00 - 0x7fff : bootloader