<s>
File	O
Allocation	O
Table	O
(	O
FAT	O
)	O
is	O
a	O
file	B-Application
system	I-Application
developed	O
for	O
personal	O
computers	O
and	O
was	O
the	O
default	O
filesystem	B-Application
for	O
MS-DOS	B-Application
and	O
Windows	B-Application
9x	O
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
Originally	O
developed	O
in	O
1977	O
for	O
use	O
on	O
floppy	B-Device
disks	I-Device
,	O
it	O
was	O
adapted	O
for	O
use	O
on	O
hard	B-Device
disks	I-Device
and	O
other	O
devices	O
.	O
</s>
<s>
FAT	O
was	O
replaced	O
with	O
NTFS	B-Application
as	O
the	O
default	O
file	B-Application
system	I-Application
on	O
Microsoft	O
operating	B-General_Concept
systems	I-General_Concept
starting	O
with	O
Windows	B-Application
XP	I-Application
.	O
</s>
<s>
Nevertheless	O
,	O
FAT	O
continues	O
to	O
be	O
used	O
on	O
flash	B-Device
and	O
other	O
solid-state	B-Device
memory	B-Device
cards	I-Device
and	O
modules	O
(	O
including	O
USB	O
flash	B-Device
drives	I-Device
)	O
,	O
many	O
portable	O
and	O
embedded	O
devices	O
because	O
of	O
its	O
compatibility	O
and	O
ease	O
of	O
implementation	O
.	O
</s>
<s>
FAT	O
was	O
also	O
used	O
on	O
hard	B-Device
disks	I-Device
throughout	O
the	O
DOS	B-Device
and	O
Windows	B-Application
9x	O
eras	O
.	O
</s>
<s>
Microsoft	O
introduced	O
NTFS	B-Application
with	O
the	O
Windows	B-Device
NT	I-Device
platform	O
in	O
1993	O
,	O
but	O
FAT	O
remained	O
the	O
standard	O
for	O
the	O
home	O
user	O
until	O
the	O
introduction	O
of	O
Windows	B-Application
XP	I-Application
in	O
2001	O
.	O
</s>
<s>
Windows	B-Device
Me	I-Device
was	O
the	O
final	O
version	O
of	O
Windows	B-Application
to	O
use	O
FAT	O
as	O
its	O
default	O
file	B-Application
system	I-Application
.	O
</s>
<s>
For	O
floppy	B-Device
disks	I-Device
,	O
FAT	O
has	O
been	O
standardized	O
as	O
ECMA-107	O
and	O
ISO/IEC9293:1994	O
(	O
superseding	O
ISO9293:1987	O
)	O
.	O
</s>
<s>
While	O
FAT12	O
is	O
used	O
on	O
floppy	B-Device
disks	I-Device
,	O
FAT16	O
and	O
FAT32	O
are	O
typically	O
found	O
on	O
the	O
larger	O
media	O
.	O
</s>
<s>
FAT	O
is	O
used	O
internally	O
for	O
the	O
EFI	B-Device
system	I-Device
partition	I-Device
in	O
the	O
boot	O
stage	O
of	O
EFI-compliant	O
computers	O
.	O
</s>
<s>
Hidden	O
FAT	O
filesystems	B-Application
are	O
also	O
used	O
in	O
the	O
UEFI	B-Architecture
boot	O
partition	B-Application
on	O
modern	O
PCs	O
.	O
</s>
<s>
FAT	O
is	O
still	O
used	O
in	O
drives	O
expected	O
to	O
be	O
used	O
by	O
multiple	O
operating	B-General_Concept
systems	I-General_Concept
,	O
such	O
as	O
in	O
shared	O
Windows	B-Application
,	O
Linux	B-Application
and	O
DOS	B-Device
environments	O
.	O
</s>
<s>
Microsoft	B-Application
Windows	I-Application
additionally	O
comes	O
with	O
a	O
pre-installed	O
tool	O
to	O
convert	O
a	O
FAT	O
file	B-Application
system	I-Application
into	O
NTFS	B-Application
directly	O
without	O
the	O
need	O
to	O
rewrite	O
all	O
files	O
,	O
though	O
this	O
cannot	O
be	O
reversed	O
easily	O
.	O
</s>
<s>
The	O
FAT	O
file	B-Application
system	I-Application
is	O
used	O
in	O
removable	O
media	O
such	O
as	O
floppy	B-Device
disks	I-Device
,	O
super-floppies	O
,	O
memory	B-Device
and	O
flash	B-Device
memory	I-Device
cards	I-Device
or	O
USB	O
flash	B-Device
drives	I-Device
.	O
</s>
<s>
FAT	O
is	O
supported	O
by	O
portable	O
devices	O
such	O
as	O
PDAs	B-Application
,	O
digital	B-Device
cameras	I-Device
,	O
camcorders	O
,	O
media	O
players	O
,	O
and	O
mobile	O
phones	O
.	O
</s>
<s>
The	O
DCF	B-Algorithm
file	B-Application
system	I-Application
adopted	O
by	O
almost	O
all	O
digital	B-Device
cameras	I-Device
since	O
1998	O
defines	O
a	O
logical	O
file	B-Application
system	I-Application
with	O
8.3	O
filenames	O
and	O
makes	O
the	O
use	O
of	O
either	O
FAT12	O
,	O
FAT16	O
,	O
FAT32	O
or	O
exFAT	B-Application
mandatory	O
for	O
its	O
physical	O
layer	O
for	O
compatibility	O
.	O
</s>
<s>
The	O
file	B-Application
system	I-Application
uses	O
an	O
index	O
table	O
stored	O
on	O
the	O
device	O
to	O
identify	O
chains	O
of	O
data	O
storage	O
areas	O
associated	O
with	O
a	O
file	O
,	O
the	O
File	O
Allocation	O
Table	O
(	O
FAT	O
)	O
.	O
</s>
<s>
The	O
table	O
is	O
a	O
linked	B-Data_Structure
list	I-Data_Structure
of	O
entries	O
for	O
each	O
cluster	O
,	O
a	O
contiguous	O
area	O
of	O
disk	O
storage	O
.	O
</s>
<s>
The	O
root	B-Application
directory	I-Application
of	O
the	O
disk	O
contains	O
the	O
number	O
of	O
the	O
first	O
cluster	O
of	O
each	O
file	O
in	O
that	O
directory	B-Application
.	O
</s>
<s>
The	O
operating	B-General_Concept
system	I-General_Concept
can	O
then	O
traverse	O
the	O
FAT	O
,	O
looking	O
up	O
the	O
cluster	O
number	O
of	O
each	O
successive	O
part	O
of	O
the	O
disk	O
file	O
as	O
a	O
cluster	O
chain	O
until	O
the	O
end	O
of	O
the	O
file	O
is	O
reached	O
.	O
</s>
<s>
Sub-directories	O
are	O
implemented	O
as	O
special	O
files	O
containing	O
the	O
directory	B-Application
entries	O
of	O
their	O
respective	O
files	O
.	O
</s>
<s>
Each	O
entry	O
in	O
the	O
FAT	O
linked	B-Data_Structure
list	I-Data_Structure
is	O
a	O
fixed	O
number	O
of	O
bits	O
:	O
12	O
,	O
16	O
or	O
32	O
.	O
</s>
<s>
Even	O
if	O
only	O
one	O
byte	B-Application
of	O
storage	O
is	O
needed	O
to	O
extend	O
a	O
file	O
,	O
an	O
entire	O
cluster	O
must	O
be	O
allocated	O
to	O
it	O
and	O
any	O
single	O
cluster	O
can	O
not	O
hold	O
more	O
than	O
a	O
single	O
file	O
,	O
so	O
large	O
clusters	O
waste	O
much	O
disk	O
space	O
if	O
there	O
are	O
large	O
numbers	O
of	O
small	O
files	O
.	O
</s>
<s>
Originally	O
designed	O
as	O
an	O
8-bit	O
file	B-Application
system	I-Application
,	O
the	O
maximum	O
number	O
of	O
clusters	O
must	O
increase	O
as	O
disk	O
drive	O
capacity	O
increases	O
,	O
and	O
so	O
the	O
number	O
of	O
bits	O
used	O
to	O
identify	O
each	O
cluster	O
has	O
grown	O
.	O
</s>
<s>
The	O
successive	O
major	O
variants	O
of	O
the	O
FAT	B-Application
format	I-Application
are	O
named	O
after	O
the	O
number	O
of	O
table	O
element	O
bits	O
:	O
12	O
(	O
FAT12	O
)	O
,	O
16	O
(	O
FAT16	O
)	O
,	O
and	O
32	O
(	O
FAT32	O
)	O
.	O
</s>
<s>
There	O
are	O
several	O
variants	O
of	O
the	O
FAT	O
file	B-Application
system	I-Application
(	O
e.g.	O
</s>
<s>
FAT16	O
refers	O
to	O
both	O
the	O
original	O
group	O
of	O
FAT	O
file	B-Application
systems	I-Application
with	O
16-bit	O
wide	O
cluster	O
entries	O
and	O
also	O
to	O
later	O
variants	O
.	O
</s>
<s>
"	O
VFAT	O
"	O
is	O
an	O
optional	O
extension	O
for	O
long	O
file	O
names	O
,	O
which	O
can	O
work	O
on	O
top	O
of	O
any	O
FAT	O
file	B-Application
system	I-Application
.	O
</s>
<s>
Volumes	O
using	O
VFAT	O
long-filenames	O
can	O
be	O
read	O
also	O
by	O
operating	B-General_Concept
systems	I-General_Concept
not	O
supporting	O
the	O
VFAT	O
extension	O
.	O
</s>
<s>
The	O
original	O
FAT	O
file	B-Application
system	I-Application
(	O
or	O
FAT	O
structure	O
,	O
as	O
it	O
was	O
called	O
initially	O
)	O
was	O
designed	O
and	O
implemented	O
by	O
Marc	O
McDonald	O
,	O
based	O
on	O
a	O
series	O
of	O
discussions	O
between	O
McDonald	O
and	O
Bill	O
Gates	O
.	O
</s>
<s>
It	O
was	O
introduced	O
with	O
8-bit	O
table	O
elements	O
(	O
and	O
valid	O
data	O
cluster	O
numbers	O
up	O
to	O
0xBF	O
)	O
in	O
a	O
precursor	O
to	O
Microsoft	O
's	O
Standalone	O
Disk	O
BASIC-80	O
for	O
an	O
8080-based	O
successor	O
of	O
the	O
NCR	O
7200	O
model	O
VI	O
data-entry	O
terminal	O
,	O
equipped	O
with	O
8-inch	O
(	O
200mm	O
)	O
floppy	B-Device
disks	I-Device
,	O
in	O
1977	O
or	O
1978	O
.	O
</s>
<s>
In	O
1978	O
,	O
Standalone	O
Disk	O
BASIC-80	O
was	O
ported	O
to	O
the	O
8086	B-General_Concept
using	O
an	O
emulator	O
on	O
a	O
DEC	B-Device
PDP-10	I-Device
,	O
since	O
no	O
real	O
8086	B-General_Concept
systems	O
were	O
available	O
at	O
this	O
time	O
.	O
</s>
<s>
The	O
FAT	O
file	B-Application
system	I-Application
was	O
also	O
used	O
in	O
Microsoft	O
's	O
MDOS/MIDAS	O
,	O
an	O
operating	B-General_Concept
system	I-General_Concept
for	O
8080/Z80	O
platforms	O
written	O
by	O
McDonald	O
since	O
1979	O
.	O
</s>
<s>
While	O
the	O
size	O
of	O
directory	B-Application
entries	O
was	O
16	O
bytes	B-Application
in	O
Standalone	O
Disk	O
BASIC	O
,	O
MIDAS	O
instead	O
occupied	O
32bytes	O
per	O
entry	O
.	O
</s>
<s>
Tim	O
Paterson	O
of	O
Seattle	O
Computer	O
Products	O
(	O
SCP	O
)	O
was	O
first	O
introduced	O
to	O
Microsoft	O
's	O
FAT	O
structure	O
when	O
he	O
helped	O
Bob	O
O'Rear	O
adapting	O
the	O
Standalone	O
Disk	O
BASIC-86	O
emulator	O
port	O
onto	O
SCP	O
's	O
S-100	B-Architecture
bus	I-Architecture
8086	B-General_Concept
CPU	B-General_Concept
board	O
prototype	O
during	O
a	O
guest	O
week	O
at	O
Microsoft	O
in	O
May	O
1979	O
.	O
</s>
<s>
The	O
final	O
product	O
was	O
shown	O
at	O
Lifeboat	O
Associates	O
 '	O
booth	O
stand	O
at	O
the	O
National	O
Computer	O
Conference	O
in	O
New	O
York	O
on	O
June	O
4	O
–	O
7	O
,	O
1979	O
,	O
where	O
Paterson	O
learned	O
about	O
the	O
more	O
sophisticated	O
FAT	B-Application
implementation	I-Application
in	O
MDOS/MIDAS	O
and	O
McDonald	O
talked	O
to	O
him	O
about	O
the	O
design	O
of	O
the	O
file	B-Application
system	I-Application
.	O
</s>
<s>
Between	O
April	O
and	O
August	O
1980	O
,	O
while	O
borrowing	O
the	O
FAT	O
concept	O
for	O
SCP	O
's	O
own	O
8086	B-General_Concept
operating	B-General_Concept
system	I-General_Concept
QDOS	B-Operating_System
0.10	O
,	O
Tim	O
Paterson	O
extended	O
the	O
table	O
elements	O
to	O
12	O
bits	O
,	O
reduced	O
the	O
number	O
of	O
FATs	O
to	O
two	O
,	O
redefined	O
the	O
semantics	O
of	O
some	O
of	O
the	O
reserved	O
cluster	O
values	O
,	O
and	O
modified	O
the	O
disk	O
layout	O
,	O
so	O
that	O
the	O
root	B-Application
directory	I-Application
was	O
now	O
located	O
between	O
the	O
FAT	O
and	O
the	O
data	O
area	O
for	O
his	O
implementation	O
of	O
FAT12	O
.	O
</s>
<s>
Paterson	O
also	O
increased	O
the	O
nine-character	O
(	O
6.3	O
)	O
filename	O
length	O
limit	O
to	O
eleven	O
characters	O
to	O
support	O
CP/M	B-Application
-style	O
8.3	O
filenames	O
and	O
File	B-Operating_System
Control	I-Operating_System
Blocks	I-Operating_System
.	O
</s>
<s>
The	O
format	O
used	O
in	O
Microsoft	O
Standalone	O
Disk	O
BASIC	O
's	O
8-bit	O
file	B-Application
system	I-Application
precursor	O
was	O
not	O
supported	O
by	O
QDOS	B-Operating_System
.	O
</s>
<s>
By	O
August	O
1980	O
,	O
QDOS	B-Operating_System
had	O
been	O
renamed	O
86-DOS	B-Operating_System
.	O
</s>
<s>
Starting	O
with	O
86-DOS	B-Operating_System
0.42	O
,	O
the	O
size	O
and	O
layout	O
of	O
directory	B-Application
entries	O
was	O
changed	O
from	O
16bytes	O
to	O
32bytes	O
in	O
order	O
to	O
add	O
a	O
file	O
date	O
stamp	O
and	O
increase	O
the	O
theoretical	O
file	O
size	O
limit	O
beyond	O
the	O
previous	O
limit	O
of	O
16	O
MB	O
.	O
</s>
<s>
86-DOS	B-Operating_System
1.00	O
became	O
available	O
in	O
early	O
1981	O
.	O
</s>
<s>
Later	O
in	O
1981	O
,	O
86-DOS	B-Operating_System
evolved	O
into	O
Microsoft	O
's	O
MS-DOS	B-Application
and	O
IBM	B-Operating_System
PC	I-Operating_System
DOS	I-Operating_System
.	O
</s>
<s>
The	O
capability	O
to	O
read	O
previously	O
formatted	O
volumes	O
with	O
16-byte	O
directory	B-Application
entries	O
was	O
dropped	O
with	O
MS-DOS	B-Application
1.20	O
.	O
</s>
<s>
To	O
conserve	O
disk	O
space	O
,	O
two	O
12-bit	O
FAT	O
entries	O
used	O
three	O
consecutive	O
8-bit	O
bytes	B-Application
on	O
disk	O
,	O
requiring	O
manipulation	O
to	O
unpack	O
the	O
12-bit	O
values	O
.	O
</s>
<s>
This	O
was	O
sufficient	O
for	O
the	O
original	O
floppy	B-Device
disk	I-Device
drives	I-Device
,	O
and	O
small	O
hard	B-Device
disks	I-Device
up	O
to	O
32	O
megabytes	O
.	O
</s>
<s>
The	O
DOS	B-Device
formatting	O
tool	O
rejected	O
such	O
disks	O
completely	O
.	O
</s>
<s>
While	O
86-DOS	B-Operating_System
supported	O
three	O
disk	O
formats	O
(	O
250.25KB	O
,	O
616KB	O
and	O
1232KB	O
,	O
with	O
FAT	O
IDs	O
0xFF	O
and	O
0xFE	O
)	O
on	O
8-inch	O
(	O
200mm	O
)	O
floppy	B-Device
drives	I-Device
,	O
IBM	B-Device
PC	I-Device
DOS	B-Device
1.0	O
,	O
released	O
with	O
the	O
original	O
IBM	B-Device
Personal	I-Device
Computer	I-Device
in	O
1981	O
,	O
supported	O
only	O
an	O
8-sector	O
floppy	B-Device
format	O
with	O
a	O
formatted	O
capacity	O
of	O
160KB	O
(	O
FAT	O
ID	O
0xFE	O
)	O
for	O
single-sided	O
5.25-inch	O
floppy	B-Device
drives	I-Device
,	O
and	O
PC	O
DOS	B-Device
1.1	O
added	O
support	O
for	O
a	O
double-sided	B-Architecture
format	O
with	O
320KB	O
(	O
FAT	O
ID	O
0xFF	O
)	O
.	O
</s>
<s>
PC	B-Operating_System
DOS	I-Operating_System
2.0	O
introduced	O
support	O
for	O
9-sector	O
floppy	B-Device
formats	O
with	O
180KB	O
(	O
FAT	O
ID	O
0xFC	O
)	O
and	O
360KB	O
(	O
FAT	O
ID	O
0xFD	O
)	O
.	O
</s>
<s>
86-DOS1.00	O
and	O
PCDOS	B-Operating_System
1.0	O
directory	B-Application
entries	O
included	O
only	O
one	O
date	O
,	O
the	O
last	O
modified	O
date	O
.	O
</s>
<s>
PCDOS	B-Operating_System
1.1	O
added	O
the	O
last	O
modified	O
time	O
.	O
</s>
<s>
PCDOS	B-Operating_System
1.x	O
file	B-Application
attributes	I-Application
included	O
a	O
hidden	O
bit	O
and	O
system	O
bit	O
,	O
with	O
the	O
remaining	O
six	O
bits	O
undefined	O
.	O
</s>
<s>
At	O
this	O
time	O
,	O
DOS	B-Device
did	O
not	O
support	O
sub-directories	O
,	O
but	O
typically	O
there	O
were	O
only	O
a	O
few	O
dozen	O
files	O
on	O
a	O
diskette	B-Device
.	O
</s>
<s>
The	O
PC	B-Device
XT	I-Device
was	O
the	O
first	O
PC	O
with	O
an	O
IBM-supplied	O
hard	B-Device
drive	I-Device
,	O
and	O
PCDOS	B-Operating_System
2.0	O
supported	O
that	O
hard	B-Device
drive	I-Device
with	O
FAT12	O
(	O
FAT	O
ID	O
0xF8	O
)	O
.	O
</s>
<s>
The	O
fixed	O
assumption	O
of	O
8sectors	O
per	O
clusters	O
on	O
hard	B-Device
disks	I-Device
practically	O
limited	O
the	O
maximum	O
partition	B-Application
size	O
to	O
16MB	O
for	O
512byte	O
sectors	O
and	O
4KB	O
clusters	O
.	O
</s>
<s>
The	O
BIOS	B-Device
Parameter	I-Device
Block	I-Device
(	O
BPB	O
)	O
was	O
introduced	O
with	O
PCDOS2.0	O
as	O
well	O
,	O
and	O
this	O
version	O
also	O
added	O
read-only	O
,	O
archive	O
,	O
volume	B-Application
label	I-Application
,	O
and	O
directory	B-Application
attribute	O
bits	O
for	O
hierarchical	O
sub-directories	O
.	O
</s>
<s>
MS-DOS	B-Application
3.0	O
introduced	O
support	O
for	O
high-density	O
1.2MB	O
5.25-inch	O
diskettes	B-Device
(	O
media	O
descriptor	O
0xF9	O
)	O
,	O
which	O
notably	O
had	O
15sectors	O
per	O
track	O
,	O
hence	O
more	O
space	O
for	O
the	O
FATs	O
.	O
</s>
<s>
FAT12	O
remains	O
in	O
use	O
on	O
all	O
common	O
floppy	B-Device
disks	I-Device
,	O
including	O
1.44MB	O
and	O
later	O
2.88MB	O
disks	O
(	O
media	O
descriptor	O
byte	B-Application
0xF0	O
)	O
.	O
</s>
<s>
In	O
1984	O
,	O
IBM	O
released	O
the	O
PC	B-Operating_System
AT	I-Operating_System
,	O
which	O
required	O
PCDOS3.0	O
to	O
access	O
its	O
20MB	O
hard	B-Device
disk	I-Device
.	O
</s>
<s>
However	O
,	O
the	O
maximum	O
possible	O
number	O
of	O
sectors	O
and	O
the	O
maximum	O
partition	B-Application
size	O
of	O
32MB	O
did	O
not	O
change	O
.	O
</s>
<s>
A	O
partition	B-Application
type	I-Application
0x04	O
indicates	O
this	O
form	O
of	O
FAT16	O
with	O
less	O
than	O
65,536	O
sectors	O
(	O
less	O
than	O
32MB	O
for	O
sector	O
size	O
512	O
)	O
.	O
</s>
<s>
The	O
benefit	O
of	O
FAT16	O
was	O
the	O
use	O
of	O
smaller	O
clusters	O
,	O
making	O
disk	O
usage	O
more	O
efficient	O
,	O
particularly	O
for	O
large	O
numbers	O
of	O
files	O
only	O
a	O
few	O
hundred	O
bytes	B-Application
in	O
size	O
.	O
</s>
<s>
As	O
MS-DOS3.0	O
formatted	O
all	O
16MB-32MB	O
partitions	B-Application
in	O
the	O
FAT16	O
format	O
,	O
a	O
20MB	O
hard	B-Device
disk	I-Device
formatted	O
under	O
MS-DOS3.0	O
was	O
not	O
accessible	O
by	O
MS-DOS2.0	O
.	O
</s>
<s>
MS-DOS3.0	O
to	O
MS-DOS3.30	O
could	O
still	O
access	O
FAT12	O
partitions	B-Application
under	O
15MB	O
,	O
but	O
required	O
all	O
16MB-32MB	O
partitions	B-Application
to	O
be	O
FAT16	O
,	O
and	O
so	O
could	O
not	O
access	O
MS-DOS2.0	O
partitions	B-Application
in	O
this	O
size	O
range	O
.	O
</s>
<s>
MS-DOS3.31	O
and	O
higher	O
could	O
access	O
16MB-32MB	O
FAT12	O
partitions	B-Application
again	O
.	O
</s>
<s>
MS-DOS	B-Application
and	O
PCDOS	B-Operating_System
implementations	O
of	O
FAT12	O
and	O
FAT16	O
could	O
not	O
access	O
disk	B-Application
partitions	I-Application
larger	O
than	O
32	O
megabytes	O
.	O
</s>
<s>
Several	O
manufacturers	O
developed	O
their	O
own	O
FAT	O
variants	O
within	O
their	O
OEM	O
versions	O
of	O
MS-DOS	B-Application
.	O
</s>
<s>
Some	O
vendors	O
(	O
AST	O
and	O
NEC	O
)	O
supported	O
eight	O
,	O
instead	O
of	O
the	O
standard	O
four	O
,	O
primary	O
partition	B-Application
entries	O
in	O
their	O
custom	O
extended	O
Master	B-Device
Boot	I-Device
Record	I-Device
(	O
MBR	B-Device
)	O
,	O
and	O
they	O
adapted	O
MS-DOS	B-Application
to	O
use	O
more	O
than	O
a	O
single	O
primary	O
partition	B-Application
.	O
</s>
<s>
Other	O
vendors	O
worked	O
around	O
the	O
volume	O
size	O
limits	O
imposed	O
by	O
the	O
16-bit	O
sector	O
entries	O
by	O
increasing	O
the	O
apparent	O
size	O
of	O
the	O
sectors	O
the	O
file	B-Application
system	I-Application
operated	O
on	O
.	O
</s>
<s>
The	O
DOS-BIOS	O
or	O
System	O
BIOS	O
would	O
then	O
combine	O
multiple	O
physical	O
sectors	O
into	O
logical	O
sectors	O
for	O
the	O
file	B-Application
system	I-Application
to	O
work	O
with	O
.	O
</s>
<s>
These	O
changes	O
were	O
transparent	O
to	O
the	O
file	B-Application
system	I-Application
implementation	O
in	O
the	O
DOS	B-Device
kernel	O
.	O
</s>
<s>
The	O
underlying	O
DOS-BIOS	O
translated	O
these	O
logical	O
sectors	O
into	O
physical	O
sectors	O
according	O
to	O
partitioning	B-Application
information	O
and	O
the	O
drive	O
's	O
physical	O
geometry	O
.	O
</s>
<s>
The	O
drawback	O
of	O
this	O
approach	O
was	O
increased	O
memory	B-Device
used	O
for	O
sector	O
buffering	O
and	O
deblocking	O
.	O
</s>
<s>
Since	O
older	O
DOS	B-Device
versions	O
could	O
not	O
use	O
large	O
logical	O
sectors	O
,	O
the	O
OEMs	O
introduced	O
new	O
partition	B-Application
IDs	I-Application
for	O
their	O
FAT	O
variants	O
in	O
order	O
to	O
hide	O
them	O
from	O
off-the-shelf	O
issues	O
of	O
MS-DOS	B-Application
and	O
PC	B-Operating_System
DOS	I-Operating_System
.	O
</s>
<s>
Known	O
partition	B-Application
IDs	I-Application
for	O
logical	O
sectored	O
FATs	O
include	O
:	O
0x08	O
(	O
Commodore	O
MS-DOS	B-Application
3.x	O
)	O
,	O
0x11	O
(	O
Leading	O
Edge	O
MS-DOS	B-Application
3.x	O
)	O
,	O
0x14	O
(	O
AST	O
MS-DOS	B-Application
3.x	O
)	O
,	O
0x24	O
(	O
NEC	O
MS-DOS	B-Application
3.30	O
)	O
,	O
0x56	O
(	O
AT&T	O
MS-DOS	B-Application
3.x	O
)	O
,	O
0xE5	O
(	O
Tandy	O
MS-DOS	B-Application
)	O
,	O
0xF2	O
(	O
Sperry	O
IT	O
MS-DOS	B-Application
3.x	O
,	O
Unisys	O
MS-DOS	B-Application
3.3	O
–	O
also	O
used	O
by	O
Digital	B-Operating_System
Research	I-Operating_System
DOS	I-Operating_System
Plus	I-Operating_System
2.1	O
)	O
.	O
</s>
<s>
OEM	O
versions	O
like	O
ToshibaMS-DOS	O
,	O
WyseMS-DOS3.2	O
and	O
3.3	O
,	O
as	O
well	O
as	O
ZenithMS-DOS	O
are	O
also	O
known	O
to	O
have	O
utilized	O
logical	O
sectoring	O
.	O
</s>
<s>
While	O
non-standard	O
and	O
sub-optimal	O
,	O
these	O
FAT	O
variants	O
are	O
perfectly	O
valid	O
according	O
to	O
the	O
specifications	O
of	O
the	O
file	B-Application
system	I-Application
itself	O
.	O
</s>
<s>
Therefore	O
,	O
even	O
if	O
default	O
issues	O
of	O
MS-DOS	B-Application
and	O
PCDOS	B-Operating_System
were	O
not	O
able	O
to	O
cope	O
with	O
them	O
,	O
most	O
of	O
these	O
vendor-specific	O
FAT12	O
and	O
FAT16	O
variants	O
can	O
be	O
mounted	O
by	O
more	O
flexible	O
file	B-Application
system	I-Application
implementations	O
in	O
operating	B-General_Concept
systems	I-General_Concept
such	O
as	O
DR-DOS	B-Application
,	O
simply	O
by	O
changing	O
the	O
partition	B-Application
ID	I-Application
to	O
one	O
of	O
the	O
recognized	O
types	O
.	O
</s>
<s>
Also	O
,	O
if	O
they	O
no	O
longer	O
need	O
to	O
be	O
recognized	O
by	O
their	O
original	O
operating	B-General_Concept
systems	I-General_Concept
,	O
existing	O
partitions	B-Application
can	O
be	O
"	O
converted	O
"	O
into	O
FAT12	O
and	O
FAT16	O
volumes	O
more	O
compliant	O
with	O
versions	O
of	O
MS-DOS/PCDOS4.0	O
–	O
6.3	O
,	O
which	O
do	O
not	O
support	O
sector	O
sizes	O
different	O
from	O
512bytes	O
,	O
by	O
switching	O
to	O
a	O
BPB	O
with	O
32-bit	O
entry	O
for	O
the	O
number	O
of	O
sectors	O
,	O
as	O
introduced	O
since	O
DOS3.31	O
(	O
see	O
FAT16B	O
below	O
)	O
,	O
keeping	O
the	O
cluster	O
size	O
and	O
reducing	O
the	O
logical	O
sector	O
size	O
in	O
the	O
BPB	O
down	O
to	O
512bytes	O
,	O
while	O
at	O
the	O
same	O
time	O
increasing	O
the	O
counts	O
of	O
logical	O
sectors	O
per	O
cluster	O
,	O
reserved	O
logical	O
sectors	O
,	O
total	O
logical	O
sectors	O
,	O
and	O
logical	O
sectors	O
per	O
FAT	O
by	O
the	O
same	O
factor	O
.	O
</s>
<s>
A	O
parallel	O
development	O
in	O
MS-DOS	B-Application
/	O
PCDOS	B-Operating_System
which	O
allowed	O
an	O
increase	O
in	O
the	O
maximum	O
possible	O
FAT	O
size	O
was	O
the	O
introduction	O
of	O
multiple	O
FAT	O
partitions	B-Application
on	O
a	O
hard	B-Device
disk	I-Device
.	O
</s>
<s>
To	O
allow	O
the	O
use	O
of	O
more	O
FAT	O
partitions	B-Application
in	O
a	O
compatible	O
way	O
,	O
a	O
new	O
partition	B-Application
type	I-Application
was	O
introduced	O
in	O
PCDOS3.2	O
(	O
1986	O
)	O
,	O
the	O
extended	B-Application
partition	I-Application
(	O
EBR	B-Application
)	O
,	O
which	O
is	O
a	O
container	O
for	O
an	O
additional	O
partition	B-Application
called	O
logical	B-Application
drive	I-Application
.	O
</s>
<s>
Since	O
PCDOS3.3	O
(	O
April	O
1987	O
)	O
,	O
there	O
is	O
another	O
,	O
optional	O
extended	B-Application
partition	I-Application
containing	O
the	O
next	O
logical	B-Application
drive	I-Application
,	O
and	O
so	O
on	O
.	O
</s>
<s>
The	O
MBR	B-Device
of	O
a	O
hard	B-Device
disk	I-Device
can	O
either	O
define	O
up	O
to	O
four	O
primary	O
partitions	B-Application
,	O
or	O
an	O
extended	B-Application
partition	I-Application
in	O
addition	O
to	O
up	O
to	O
three	O
primary	O
partitions	B-Application
.	O
</s>
<s>
In	O
November	O
1987	O
,	O
Compaq	O
Personal	O
Computer	O
DOS	B-Device
3.31	O
(	O
a	O
modified	O
OEM	O
version	O
of	O
MS-DOS3.3	O
released	O
by	O
Compaq	O
with	O
their	O
machines	O
)	O
introduced	O
what	O
today	O
is	O
simply	O
known	O
as	O
the	O
FAT16	O
format	O
,	O
with	O
the	O
expansion	O
of	O
the	O
16-bit	O
disk	O
sector	O
count	O
to	O
32bits	O
in	O
the	O
BPB	O
.	O
</s>
<s>
Although	O
the	O
on-disk	O
changes	O
were	O
minor	O
,	O
the	O
entire	O
DOS	B-Device
disk	O
driver	O
had	O
to	O
be	O
converted	O
to	O
use	O
32-bit	O
sector	O
numbers	O
,	O
a	O
task	O
complicated	O
by	O
the	O
fact	O
that	O
it	O
was	O
written	O
in	O
16-bit	O
assembly	B-Language
language	I-Language
.	O
</s>
<s>
The	O
result	O
was	O
initially	O
called	O
the	O
DOS	B-Device
3.31	O
Large	O
File	B-Application
System	I-Application
.	O
</s>
<s>
Microsoft	O
's	O
DSKPROBE	O
tool	O
refers	O
to	O
type	O
0x06	O
as	O
BigFAT	O
,	O
whereas	O
some	O
older	O
versions	O
of	O
FDISK	B-Application
described	O
it	O
as	O
BIGDOS	O
.	O
</s>
<s>
Since	O
older	O
versions	O
of	O
DOS	B-Device
were	O
not	O
designed	O
to	O
cope	O
with	O
more	O
than	O
65,535	O
sectors	O
,	O
it	O
was	O
necessary	O
to	O
introduce	O
a	O
new	O
partition	B-Application
type	I-Application
for	O
this	O
format	O
in	O
order	O
to	O
hide	O
it	O
from	O
pre-3.31	O
issues	O
of	O
DOS	B-Device
.	O
</s>
<s>
The	O
original	O
form	O
of	O
FAT16	O
(	O
with	O
less	O
than	O
65,536	O
sectors	O
)	O
had	O
a	O
partition	B-Application
type	I-Application
0x04	O
.	O
</s>
<s>
Therefore	O
,	O
newer	O
operating	B-General_Concept
systems	I-General_Concept
supporting	O
the	O
FAT16B	O
format	O
can	O
cope	O
also	O
with	O
the	O
original	O
FAT16	O
format	O
without	O
any	O
necessary	O
changes	O
.	O
</s>
<s>
If	O
partitions	B-Application
to	O
be	O
used	O
by	O
pre-DOS3.31	O
issues	O
of	O
DOS	B-Device
need	O
to	O
be	O
created	O
by	O
modern	O
tools	O
,	O
the	O
only	O
criteria	O
theoretically	O
necessary	O
to	O
meet	O
are	O
a	O
sector	O
count	O
of	O
less	O
than	O
65536	O
,	O
and	O
the	O
usage	O
of	O
the	O
old	O
partition	B-Application
ID	I-Application
(	O
0x04	O
)	O
.	O
</s>
<s>
In	O
practice	O
however	O
,	O
type	O
0x01	O
and	O
0x04	O
primary	O
partitions	B-Application
should	O
not	O
be	O
physically	O
located	O
outside	O
the	O
first	O
32MB	O
of	O
the	O
disk	O
,	O
due	O
to	O
other	O
restrictions	O
in	O
MS-DOS2.x	O
,	O
which	O
could	O
not	O
cope	O
with	O
them	O
otherwise	O
.	O
</s>
<s>
The	O
limit	O
on	O
partition	B-Application
size	O
was	O
dictated	O
by	O
the	O
8-bit	O
signed	B-Algorithm
count	O
of	O
sectors	O
per	O
cluster	O
,	O
which	O
originally	O
had	O
a	O
maximum	O
power-of-two	O
value	O
of	O
64	O
.	O
</s>
<s>
With	O
the	O
standard	O
hard	B-Device
disk	I-Device
sector	O
size	O
of	O
512bytes	O
,	O
this	O
gives	O
a	O
maximum	O
of	O
32KB	O
cluster	O
size	O
,	O
thereby	O
fixing	O
the	O
"	O
definitive	O
"	O
limit	O
for	O
the	O
FAT16	O
partition	B-Application
size	O
at	O
2GB	O
for	O
sector	O
size	O
512	O
.	O
</s>
<s>
On	O
magneto-optical	B-Device
media	O
,	O
which	O
can	O
have	O
1	O
or	O
2KB	O
sectors	O
instead	O
of	O
0.5KB	O
,	O
this	O
size	O
limit	O
is	O
proportionally	O
larger	O
.	O
</s>
<s>
Much	O
later	O
,	O
Windows	B-Application
NT	O
increased	O
the	O
maximum	O
cluster	O
size	O
to	O
64KB	O
,	O
by	O
considering	O
the	O
sectors-per-cluster	O
count	O
as	O
unsigned	B-Algorithm
.	O
</s>
<s>
However	O
,	O
the	O
resulting	O
format	O
was	O
not	O
compatible	O
with	O
any	O
other	O
FAT	B-Application
implementation	I-Application
of	O
the	O
time	O
,	O
and	O
it	O
generated	O
greater	O
internal	O
fragmentation	O
.	O
</s>
<s>
Windows	B-Device
98	I-Device
,	O
SE	O
and	O
ME	O
also	O
supported	O
reading	O
and	O
writing	O
this	O
variant	O
,	O
but	O
its	O
disk	O
utilities	O
did	O
not	O
work	O
with	O
it	O
and	O
some	O
FCB	B-Operating_System
services	O
are	O
not	O
available	O
for	O
such	O
volumes	O
.	O
</s>
<s>
Prior	O
to	O
1995	O
,	O
versions	O
of	O
DOS	B-Device
accessed	O
the	O
disk	O
via	O
CHS	B-Device
addressing	O
only	O
.	O
</s>
<s>
When	O
Windows	B-Application
95( 	O
MS-DOS	B-Application
7.0	O
)	O
introduced	O
LBA	B-Device
disk	O
access	O
,	O
partitions	B-Application
could	O
start	O
being	O
physically	O
located	O
outside	O
the	O
first	O
c	O
.	O
8GB	O
of	O
this	O
disk	O
and	O
thereby	O
out	O
of	O
the	O
reach	O
of	O
the	O
traditional	O
CHS	B-Device
addressing	O
scheme	O
.	O
</s>
<s>
Partitions	B-Application
partially	O
or	O
fully	O
located	O
beyond	O
the	O
CHS	B-Device
barrier	O
therefore	O
had	O
to	O
be	O
hidden	O
from	O
non-LBA-enabled	O
operating	B-General_Concept
systems	I-General_Concept
by	O
using	O
the	O
new	O
partition	B-Application
type	I-Application
0x0E	O
in	O
the	O
partition	B-Application
table	O
instead	O
.	O
</s>
<s>
FAT16	O
partitions	B-Application
using	O
this	O
partition	B-Application
type	I-Application
are	O
also	O
named	O
FAT16X	O
.	O
</s>
<s>
The	O
only	O
difference	O
,	O
compared	O
to	O
previous	O
FAT16	O
partitions	B-Application
,	O
is	O
the	O
fact	O
that	O
some	O
CHS-related	O
geometry	O
entries	O
in	O
the	O
BPB	O
record	O
,	O
namely	O
the	O
number	O
of	O
sectors	O
per	O
track	O
and	O
the	O
number	O
of	O
heads	O
,	O
may	O
contain	O
no	O
or	O
misleading	O
values	O
and	O
should	O
not	O
be	O
used	O
.	O
</s>
<s>
The	O
number	O
of	O
root	B-Application
directory	I-Application
entries	O
available	O
for	O
FAT12	O
and	O
FAT16	O
is	O
determined	O
when	O
the	O
volume	O
is	O
formatted	O
,	O
and	O
is	O
stored	O
in	O
a	O
16-bit	O
field	O
.	O
</s>
<s>
For	O
a	O
given	O
number	O
RDE	O
and	O
sector	O
size	O
SS	O
,	O
the	O
number	O
RDS	O
of	O
root	B-Application
directory	I-Application
sectors	O
is	O
RDS	O
=	O
ceil( ( RDE	O
×	O
32	O
)	O
/	O
SS	O
)	O
,	O
and	O
RDE	O
is	O
normally	O
chosen	O
to	O
fill	O
these	O
sectors	O
,	O
i.e.	O
,	O
RDE	O
×	O
32	O
=	O
RDS	O
×	O
SS	O
.	O
</s>
<s>
FAT12	O
and	O
FAT16	O
media	O
typically	O
use	O
512	O
root	B-Application
directory	I-Application
entries	O
on	O
non-floppy	O
media	O
.	O
</s>
<s>
In	O
order	O
to	O
overcome	O
the	O
volume	O
size	O
limit	O
of	O
FAT16	O
,	O
while	O
at	O
the	O
same	O
time	O
allowing	O
DOS	B-Device
real-mode	B-Application
code	O
to	O
handle	O
the	O
format	O
,	O
Microsoft	O
designed	O
a	O
new	O
version	O
of	O
the	O
file	B-Application
system	I-Application
,	O
FAT32	O
,	O
which	O
supported	O
an	O
increased	O
number	O
of	O
possible	O
clusters	O
,	O
but	O
could	O
reuse	O
most	O
of	O
the	O
existing	O
code	O
,	O
so	O
that	O
the	O
conventional	B-Device
memory	I-Device
footprint	O
was	O
increased	O
by	O
less	O
than	O
5	O
KB	O
under	O
DOS	B-Device
.	O
</s>
<s>
The	O
built-in	O
Windows	B-Application
shell	I-Application
disk	O
format	O
tool	O
on	O
Windows	B-Device
NT	I-Device
only	O
supports	O
volume	O
sizes	O
up	O
to	O
32GB	O
,	O
but	O
Windows	B-Application
supports	O
reading	O
and	O
writing	O
to	O
preexisting	O
larger	O
FAT32	O
volumes	O
,	O
and	O
these	O
can	O
be	O
created	O
with	O
the	O
command	B-Device
prompt	I-Device
,	O
PowerShell	B-Application
or	O
third-party	O
tools	O
,	O
or	O
by	O
formatting	O
the	O
volume	O
on	O
a	O
non-Windows	O
system	O
or	O
on	O
a	O
Windows	B-Application
9x	O
system	O
with	O
FAT32	O
support	O
and	O
then	O
transferring	O
it	O
to	O
the	O
Windows	B-Device
NT	I-Device
system	O
.	O
</s>
<s>
The	O
maximal	O
possible	O
size	O
for	O
a	O
file	O
on	O
a	O
FAT32	O
volume	O
is	O
4GB	O
minus	O
1	O
byte	B-Application
,	O
or	O
4,294,967,295	O
(	O
232−1	O
)	O
bytes	B-Application
.	O
</s>
<s>
This	O
limit	O
is	O
a	O
consequence	O
of	O
the	O
4-byte	O
file	O
length	O
entry	O
in	O
the	O
directory	B-Application
table	I-Application
and	O
would	O
also	O
affect	O
relatively	O
huge	O
FAT16	O
partitions	B-Application
enabled	O
by	O
a	O
sufficient	O
sector	O
size	O
.	O
</s>
<s>
FAT32	O
was	O
introduced	O
with	O
Windows	B-Application
95	I-Application
OSR2( 	O
MS-DOS	B-Application
7.1	O
)	O
in	O
1996	O
,	O
although	O
reformatting	O
was	O
needed	O
to	O
use	O
it	O
,	O
and	O
DriveSpace	B-General_Concept
3	O
(	O
the	O
version	O
that	O
came	O
with	O
Windows	B-Application
95	I-Application
OSR2	O
and	O
Windows	B-Device
98	I-Device
)	O
never	O
supported	O
it	O
.	O
</s>
<s>
Windows	B-Device
98	I-Device
introduced	O
a	O
utility	O
to	O
convert	O
existing	O
hard	B-Device
disks	I-Device
from	O
FAT16	O
to	O
FAT32	O
without	O
loss	O
of	O
data	O
.	O
</s>
<s>
In	O
the	O
Windows	B-Device
NT	I-Device
line	O
,	O
native	O
support	O
for	O
FAT32	O
arrived	O
in	O
Windows	B-Application
2000	I-Application
.	O
</s>
<s>
A	O
free	O
FAT32	O
driver	O
for	O
Windows	B-Device
NT	I-Device
4.0	I-Device
was	O
available	O
from	O
Winternals	O
,	O
a	O
company	O
later	O
acquired	O
by	O
Microsoft	O
.	O
</s>
<s>
Since	O
1998	O
,	O
Caldera	O
's	O
dynamically	O
loadable	O
DRFAT32	O
driver	O
could	O
be	O
used	O
to	O
enable	O
FAT32	O
support	O
in	O
DR-DOS	B-Application
.	O
</s>
<s>
The	O
first	O
version	O
of	O
DR-DOS	B-Application
to	O
natively	O
support	O
FAT32	O
and	O
LBA	B-Device
access	O
was	O
OEM	O
DR-DOS	B-Application
7.04	O
in	O
1999	O
.	O
</s>
<s>
That	O
same	O
year	O
IMS	O
introduced	O
native	O
FAT32	O
support	O
with	O
REAL/32	B-Operating_System
7.90	O
,	O
and	O
IBM	B-Language
4690	I-Language
OS	I-Language
added	O
FAT32	O
support	O
with	O
version	O
2	O
.	O
</s>
<s>
Ahead	O
Software	O
provided	O
another	O
dynamically	O
loadable	O
FAT32.EXE	O
driver	O
for	O
DR-DOS	B-Application
7.03	O
with	O
Nero	B-Application
Burning	I-Application
ROM	I-Application
in	O
2004	O
.	O
</s>
<s>
IBM	O
introduced	O
native	O
FAT32	O
support	O
with	O
OEM	O
PC	B-Operating_System
DOS	I-Operating_System
7.1	O
in	O
1999	O
.	O
</s>
<s>
Two	O
partition	B-Application
types	I-Application
have	O
been	O
reserved	O
for	O
FAT32	O
partitions	B-Application
,	O
0x0B	O
and	O
0x0C	O
.	O
</s>
<s>
The	O
latter	O
type	O
is	O
also	O
named	O
FAT32X	O
in	O
order	O
to	O
indicate	O
usage	O
of	O
LBA	B-Device
disk	O
access	O
instead	O
of	O
CHS	B-Device
.	O
</s>
<s>
On	O
such	O
partitions	B-Application
,	O
CHS-related	O
geometry	O
entries	O
,	O
namely	O
the	O
CHS	B-Device
sector	O
addresses	O
in	O
the	O
MBR	B-Device
as	O
well	O
as	O
the	O
number	O
of	O
sectors	O
per	O
track	O
and	O
the	O
number	O
of	O
heads	O
in	O
the	O
EBPB	B-Device
record	O
,	O
may	O
contain	O
no	O
or	O
misleading	O
values	O
and	O
should	O
not	O
be	O
used	O
.	O
</s>
<s>
OS/2	B-Application
heavily	O
depends	O
on	O
extended	B-Application
attributes	I-Application
(	O
EAs	B-Application
)	O
and	O
stores	O
them	O
in	O
a	O
hidden	B-Application
file	I-Application
called	O
"	O
EA␠	O
DATA.	O
␠SF	O
"	O
in	O
the	O
root	B-Application
directory	I-Application
of	O
the	O
FAT12	O
or	O
FAT16	O
volume	O
.	O
</s>
<s>
This	O
file	O
is	O
indexed	O
by	O
two	O
previously	O
reserved	O
bytes	B-Application
in	O
the	O
file	O
's	O
(	O
or	O
directory	B-Application
's	O
)	O
directory	B-Application
entry	O
at	O
offset	O
0x14	O
.	O
</s>
<s>
In	O
the	O
FAT32	O
format	O
,	O
these	O
bytes	B-Application
hold	O
the	O
upper	O
16bits	O
of	O
the	O
starting	O
cluster	O
number	O
of	O
the	O
file	O
or	O
directory	B-Application
,	O
hence	O
making	O
it	O
impossible	O
to	O
store	O
OS/2	B-Application
EAs	B-Application
on	O
FAT32	O
using	O
this	O
method	O
.	O
</s>
<s>
However	O
,	O
the	O
third-party	O
FAT32	O
installable	B-Application
file	I-Application
system	I-Application
(	O
IFS	B-Application
)	O
driver	O
FAT32.IFS	O
version	O
0.70	O
and	O
higher	O
by	O
Henk	O
Kelder	O
&	O
Netlabs	O
for	O
OS/2	B-Application
,	O
eComStation	B-Device
and	O
ArcaOS	B-Device
stores	O
extended	B-Application
attributes	I-Application
in	O
extra	O
files	O
with	O
filenames	O
having	O
the	O
string	O
"	O
␠	O
EA.	O
␠SF	O
"	O
appended	O
to	O
the	O
regular	O
filename	O
of	O
the	O
file	O
to	O
which	O
they	O
belong	O
.	O
</s>
<s>
The	O
driver	O
also	O
utilizes	O
the	O
byte	B-Application
at	O
offset	O
0x0C	O
in	O
directory	B-Application
entries	O
to	O
store	O
a	O
special	O
mark	O
byte	B-Application
indicating	O
the	O
presence	O
of	O
extended	B-Application
attributes	I-Application
to	O
help	O
speed	O
up	O
things	O
.	O
</s>
<s>
Extended	B-Application
attributes	I-Application
are	O
accessible	O
via	O
the	O
Workplace	B-Device
Shell	I-Device
desktop	O
,	O
through	O
REXX	B-Language
scripts	O
,	O
and	O
many	O
system	O
GUI	B-Application
and	O
command-line	B-Application
utilities	O
(	O
such	O
as	O
4OS2	B-Application
)	O
.	O
</s>
<s>
To	O
accommodate	O
its	O
OS/2	B-Application
subsystem	O
,	O
Windows	B-Device
NT	I-Device
supports	O
the	O
handling	O
of	O
extended	B-Application
attributes	I-Application
in	O
HPFS	B-Application
,	O
NTFS	B-Application
,	O
FAT12	O
and	O
FAT16	O
.	O
</s>
<s>
It	O
stores	O
EAs	B-Application
on	O
FAT12	O
,	O
FAT16	O
and	O
HPFS	B-Application
using	O
exactly	O
the	O
same	O
scheme	O
as	O
OS/2	B-Application
,	O
but	O
does	O
not	O
support	O
any	O
other	O
kind	O
of	O
ADS	O
as	O
held	O
on	O
NTFS	B-Application
volumes	O
.	O
</s>
<s>
Trying	O
to	O
copy	O
a	O
file	O
with	O
any	O
ADS	O
other	O
than	O
EAs	B-Application
from	O
an	O
NTFS	B-Application
volume	O
to	O
a	O
FAT	O
or	O
HPFS	B-Application
volume	O
gives	O
a	O
warning	O
message	O
with	O
the	O
names	O
of	O
the	O
ADSs	O
that	O
will	O
be	O
lost	O
.	O
</s>
<s>
It	O
does	O
not	O
support	O
the	O
FAT32.IFS	O
method	O
to	O
store	O
EAs	B-Application
on	O
FAT32	O
volumes	O
.	O
</s>
<s>
Windows	B-Application
2000	I-Application
onward	O
acts	O
exactly	O
as	O
Windows	B-Device
NT	I-Device
,	O
except	O
that	O
it	O
ignores	O
EAs	B-Application
when	O
copying	O
to	O
FAT32	O
without	O
any	O
warning	O
(	O
but	O
shows	O
the	O
warning	O
for	O
other	O
ADSs	O
,	O
like	O
"	O
Macintosh	B-Application
Finder	I-Application
Info	O
"	O
and	O
"	O
Macintosh	O
Resource	B-Operating_System
Fork	I-Operating_System
"	O
)	O
.	O
</s>
<s>
Cygwin	B-Language
uses	O
"	O
EA␠	O
DATA.	O
␠SF	O
"	O
files	O
as	O
well	O
.	O
</s>
<s>
One	O
of	O
the	O
user	B-Application
experience	I-Application
goals	O
for	O
the	O
designers	O
of	O
Windows	B-Application
95	I-Application
was	O
the	O
ability	O
to	O
use	O
long	O
filenames	O
(	O
LFNs	O
—	O
up	O
to	O
255	O
UTF-16	O
code	O
units	O
long	O
)	O
,	O
in	O
addition	O
to	O
classic	O
8.3	O
filenames	O
(	O
SFNs	O
)	O
.	O
</s>
<s>
For	O
backward	B-General_Concept
and	O
forward	B-General_Concept
compatibility	I-General_Concept
,	O
LFNs	O
were	O
implemented	O
as	O
an	O
optional	O
extension	O
on	O
top	O
of	O
the	O
existing	O
FAT	O
file	B-Application
system	I-Application
structures	O
using	O
a	O
workaround	B-Application
in	O
the	O
way	O
directory	B-Application
entries	O
are	O
laid	O
out	O
.	O
</s>
<s>
This	O
transparent	O
method	O
to	O
store	O
long	O
file	O
names	O
in	O
the	O
existing	O
FAT	O
file	B-Application
systems	I-Application
without	O
altering	O
their	O
data	O
structures	O
is	O
usually	O
known	O
as	O
VFAT	O
(	O
for	O
"	O
Virtual	O
FAT	O
"	O
)	O
after	O
the	O
Windows	B-Application
95	I-Application
virtual	B-Application
device	I-Application
driver	I-Application
.	O
</s>
<s>
Non	O
VFAT-enabled	O
operating	B-General_Concept
systems	I-General_Concept
can	O
still	O
access	O
the	O
files	O
under	O
their	O
short	O
file	O
name	O
alias	O
without	O
restrictions	O
;	O
however	O
,	O
the	O
associated	O
long	O
file	O
names	O
may	O
be	O
lost	O
when	O
files	O
with	O
long	O
filenames	O
are	O
copied	O
under	O
non	O
VFAT-aware	O
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
In	O
WindowsNT	B-Device
,	O
support	O
for	O
VFAT	O
long	O
filenames	O
began	O
with	O
version	O
3.5	B-Device
.	O
</s>
<s>
Linux	B-Application
provides	O
a	O
VFAT	O
filesystem	B-Application
driver	O
to	O
work	O
with	O
FAT	O
volumes	O
with	O
VFAT	O
long	O
filenames	O
.	O
</s>
<s>
OS/2	B-Application
added	O
long	O
filename	O
support	O
to	O
FAT	O
using	O
extended	B-Application
attributes	I-Application
(	O
EA	O
)	O
before	O
the	O
introduction	O
of	O
VFAT	O
.	O
</s>
<s>
Thus	O
,	O
VFAT	O
long	O
filenames	O
are	O
invisible	O
to	O
OS/2	B-Application
,	O
and	O
EA	O
long	O
filenames	O
are	O
invisible	O
to	O
Windows	B-Application
;	O
therefore	O
,	O
experienced	O
users	O
of	O
both	O
operating	B-General_Concept
systems	I-General_Concept
would	O
have	O
to	O
manually	O
rename	O
the	O
files	O
.	O
</s>
<s>
Human68K	O
supported	O
up	O
to	O
18.3	O
filenames	O
and	O
(	O
Shift	O
JIS	O
)	O
Kanji	O
characters	O
in	O
a	O
proprietary	O
FAT	O
file	B-Application
system	I-Application
variant	O
.	O
</s>
<s>
In	O
order	O
to	O
support	O
Java	B-Language
applications	O
,	O
the	O
FlexOS-based	O
IBM	B-Language
4690	I-Language
OS	I-Language
version	O
2	O
introduced	O
its	O
own	O
virtual	B-Application
file	I-Application
system	I-Application
(	O
VFS	O
)	O
architecture	O
to	O
store	O
long	O
filenames	O
in	O
the	O
FAT	O
file	B-Application
system	I-Application
in	O
a	O
backwards-compatible	B-General_Concept
fashion	O
.	O
</s>
<s>
If	O
enabled	O
,	O
the	O
virtual	O
filenames	O
(	O
VFN	O
)	O
are	O
available	O
under	O
separate	O
logical	B-Application
drive	I-Application
letters	O
,	O
whereas	O
the	O
real	O
filenames	O
(	O
RFN	O
)	O
remain	O
available	O
under	O
the	O
original	O
drive	O
letters	O
.	O
</s>
<s>
The	O
FAT	O
file	B-Application
system	I-Application
itself	O
is	O
not	O
designed	O
for	O
supporting	O
alternate	B-Application
data	I-Application
streams	I-Application
(	O
ADS	O
)	O
,	O
but	O
some	O
operating	B-General_Concept
systems	I-General_Concept
that	O
heavily	O
depend	O
on	O
them	O
have	O
devised	O
various	O
methods	O
for	O
handling	O
them	O
on	O
FAT	O
volumes	O
.	O
</s>
<s>
Such	O
methods	O
either	O
store	O
the	O
additional	O
information	O
in	O
extra	O
files	O
and	O
directories	B-Application
(	O
classic	B-Application
Mac	I-Application
OS	I-Application
and	O
macOS	B-Application
)	O
,	O
or	O
give	O
new	O
semantics	O
to	O
previously	O
unused	O
fields	O
of	O
the	O
FAT	O
on-disk	O
data	O
structures	O
(	O
OS/2	B-Application
and	O
Windows	B-Device
NT	I-Device
)	O
.	O
</s>
<s>
MacOS	B-Application
using	O
PC	B-Operating_System
Exchange	I-Operating_System
stores	O
its	O
various	O
dates	O
,	O
file	B-Application
attributes	I-Application
and	O
long	O
filenames	O
in	O
a	O
hidden	B-Application
file	I-Application
called	O
"	O
FINDER.DAT	O
"	O
,	O
and	O
resource	B-Operating_System
forks	I-Operating_System
(	O
a	O
common	O
MacOS	B-Application
ADS	O
)	O
in	O
a	O
subdirectory	B-Application
called	O
"	O
RESOURCE.FRK	O
"	O
,	O
in	O
every	O
directory	B-Application
where	O
they	O
are	O
used	O
.	O
</s>
<s>
From	O
PCExchange2.1	O
onwards	O
,	O
they	O
store	O
the	O
MacOS	B-Application
long	O
filenames	O
as	O
standard	O
FAT	O
long	O
filenames	O
and	O
convert	O
FAT	O
filenames	O
longer	O
than	O
31	O
characters	O
to	O
unique	O
31-character	O
filenames	O
,	O
which	O
can	O
then	O
be	O
made	O
visible	O
to	O
Macintosh	O
applications	O
.	O
</s>
<s>
macOS	B-Application
stores	O
resource	B-Operating_System
forks	I-Operating_System
and	O
metadata	O
(	O
file	B-Application
attributes	I-Application
,	O
other	O
ADS	O
)	O
using	O
AppleDouble	B-Application
format	I-Application
in	O
a	O
hidden	B-Application
file	I-Application
with	O
a	O
name	O
constructed	O
from	O
the	O
owner	O
filename	O
prefixed	O
with	O
"	O
._	O
"	O
,	O
and	O
Finder	B-Application
stores	O
some	O
folder	O
and	O
file	O
metadata	O
in	O
a	O
hidden	B-Application
file	I-Application
called	O
"	O
.DS_Store	O
"	O
(	O
but	O
note	O
that	O
Finder	B-Application
uses	O
.DS_Store	O
even	O
on	O
macOS	B-Application
 '	O
native	O
filesystem	B-Application
,	O
HFS+	B-Application
)	O
.	O
</s>
<s>
Early	O
Linux	B-Application
distributions	O
also	O
supported	O
a	O
format	O
known	O
as	O
UMSDOS	O
,	O
a	O
FAT	O
variant	O
with	O
Unix	O
file	B-Application
attributes	I-Application
(	O
such	O
as	O
long	O
file	O
name	O
and	O
access	O
permissions	O
)	O
stored	O
in	O
a	O
separate	O
file	O
called	O
"	O
--linux-.---	O
"	O
.	O
</s>
<s>
UMSDOS	O
fell	O
into	O
disuse	O
after	O
VFAT	O
was	O
released	O
and	O
it	O
is	O
not	O
enabled	O
by	O
default	O
in	O
Linux	B-Application
from	O
version	O
2.5.7	O
onwards	O
.	O
</s>
<s>
For	O
some	O
time	O
,	O
Linux	B-Application
also	O
provided	O
combined	O
support	O
for	O
UMSDOS-style	O
permissions	O
and	O
VFAT	O
long	O
filenames	O
through	O
UVFAT	O
.	O
</s>
<s>
In	O
2007	O
the	O
open	O
FAT+	O
draft	O
proposed	O
how	O
to	O
store	O
larger	B-Application
files	I-Application
up	O
to	O
256GB	O
minus	O
1byte	O
,	O
or	O
274,877,906,943	O
(	O
238−1	O
)	O
bytes	B-Application
,	O
on	O
slightly	O
modified	O
and	O
otherwise	O
backward-compatible	B-General_Concept
FAT32	O
volumes	O
,	O
but	O
imposes	O
a	O
risk	O
that	O
disk	O
tools	O
or	O
FAT32	B-Application
implementations	I-Application
not	O
aware	O
of	O
this	O
extension	O
may	O
truncate	O
or	O
delete	O
files	O
exceeding	O
the	O
normal	O
FAT32	O
file	O
size	O
limit	O
.	O
</s>
<s>
Support	O
for	O
FAT32+	O
and	O
FAT16+	O
is	O
limited	O
to	O
some	O
versions	O
of	O
DR-DOS	B-Application
and	O
not	O
available	O
in	O
mainstream	O
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
(	O
This	O
extension	O
is	O
critically	O
incompatible	O
with	O
the	O
/EAS	O
option	O
of	O
the	O
FAT32.IFS	O
method	O
to	O
store	O
OS/2	B-Application
extended	B-Application
attributes	I-Application
on	O
FAT32	O
volumes	O
.	O
)	O
</s>
<s>
In	O
its	O
NetWare	B-Application
File	I-Application
System	I-Application
(	O
NWFS	B-Application
)	O
Novell	O
implemented	O
a	O
heavily	O
modified	O
variant	O
of	O
a	O
FAT	O
file	B-Application
system	I-Application
for	O
the	O
NetWare	B-Operating_System
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
For	O
larger	B-Application
files	I-Application
it	O
utilized	O
a	O
performance	O
feature	O
named	O
Turbo	B-Application
FAT	I-Application
.	O
</s>
<s>
FATX	O
is	O
a	O
family	O
of	O
file	B-Application
systems	I-Application
designed	O
for	O
Microsoft	O
's	O
Xbox	B-Operating_System
video	B-Device
game	I-Device
console	I-Device
hard	B-Device
disk	I-Device
drives	I-Device
and	O
memory	B-Device
cards	I-Device
,	O
introduced	O
in	O
2001	O
.	O
</s>
<s>
While	O
resembling	O
the	O
same	O
basic	O
design	O
ideas	O
as	O
FAT16	O
and	O
FAT32	O
,	O
the	O
FATX16	O
and	O
FATX32	O
on-disk	O
structures	O
are	O
simplified	O
,	O
but	O
fundamentally	O
incompatible	O
with	O
normal	O
FAT16	O
and	O
FAT32	O
file	B-Application
systems	I-Application
,	O
making	O
it	O
impossible	O
for	O
normal	O
FAT	O
file	B-Application
system	I-Application
drivers	O
to	O
mount	O
such	O
volumes	O
.	O
</s>
<s>
Clusters	O
are	O
typically	O
16KB	O
in	O
size	O
and	O
there	O
is	O
only	O
one	O
copy	O
of	O
the	O
FAT	O
on	O
the	O
Xbox	B-Operating_System
.	O
</s>
<s>
Directory	B-Application
entries	O
are	O
64bytes	O
in	O
size	O
instead	O
of	O
the	O
normal	O
32	O
bytes	B-Application
.	O
</s>
<s>
On	O
the	B-Operating_System
Xbox	I-Operating_System
360	I-Operating_System
,	O
the	O
epoch	O
is	O
1980	O
.	O
</s>
<s>
exFAT	B-Application
is	O
a	O
file	B-Application
system	I-Application
introduced	O
with	O
Windows	B-Operating_System
Embedded	I-Operating_System
CE	I-Operating_System
6.0	I-Operating_System
in	O
November	O
2006	O
and	O
brought	O
to	O
the	O
WindowsNT	B-Device
family	O
with	O
Vista	O
Service	O
Pack	O
1	O
and	O
Windows	B-Application
XP	I-Application
Service	I-Application
Pack	I-Application
3	I-Application
(	O
or	O
separate	O
installation	O
of	O
WindowsXP	B-Application
Update	O
KB955704	O
)	O
.	O
</s>
<s>
exFAT	B-Application
is	O
intended	O
for	O
use	O
on	O
flash	B-Device
drives	I-Device
and	O
memory	B-Device
cards	I-Device
such	O
as	O
SDXC	O
and	O
Memory	B-Device
Stick	O
XC	O
,	O
where	O
FAT32	O
is	O
otherwise	O
used	O
.	O
</s>
<s>
Its	O
main	O
benefit	O
is	O
its	O
exceeding	O
of	O
the	O
4GB	O
file	O
size	O
limit	O
,	O
as	O
file	O
size	O
references	O
are	O
stored	O
with	O
eight	O
instead	O
of	O
four	O
bytes	B-Application
,	O
increasing	O
the	O
limit	O
to	O
264−1	O
bytes	B-Application
.	O
</s>
<s>
Microsoft	O
's	O
GUI	B-Application
and	O
command-line	B-Application
format	O
utilities	O
offer	O
it	O
as	O
an	O
alternative	O
to	O
NTFS	B-Application
(	O
and	O
,	O
for	O
smaller	O
partitions	B-Application
,	O
to	O
FAT16B	O
and	O
FAT32	O
)	O
.	O
</s>
<s>
The	O
MBR	B-Device
partition	B-Application
type	I-Application
is	O
0x07	O
(	O
the	O
same	O
as	O
used	O
for	O
IFS	B-Application
,	O
HPFS	B-Application
,	O
and	O
NTFS	B-Application
)	O
.	O
</s>
<s>
Logical	O
geometry	O
information	O
located	O
in	O
the	O
VBR	B-Device
is	O
stored	O
in	O
a	O
format	O
not	O
resembling	O
any	O
kind	O
of	O
BPB	O
.	O
</s>
<s>
In	O
early	O
2010	O
,	O
the	O
file	B-Application
system	I-Application
was	O
reverse-engineered	O
by	O
the	O
SANS	O
Institute	O
.	O
</s>
<s>
On	O
August	O
28	O
,	O
2019	O
,	O
Microsoft	O
announced	O
that	O
it	O
will	O
be	O
making	O
the	O
technical	O
specification	O
for	O
exFAT	B-Application
publicly	O
available	O
so	O
that	O
it	O
can	O
be	O
used	O
in	O
the	O
Linux	B-Application
kernel	O
and	O
other	O
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
Microsoft	O
applied	O
for	O
,	O
and	O
was	O
granted	O
,	O
a	O
series	O
of	O
patents	O
for	O
key	O
parts	O
of	O
the	O
FAT	O
file	B-Application
system	I-Application
in	O
the	O
mid-1990s	O
.	O
</s>
<s>
All	O
four	O
pertain	O
to	O
long-filename	O
extensions	O
to	O
FAT	O
first	O
seen	O
in	O
Windows	B-Application
95	I-Application
:	O
U.S.	O
patent	O
5	O
,	O
579	O
,	O
517	O
,	O
U.S.	O
patent	O
5	O
,	O
745	O
,	O
902	O
,	O
U.S.	O
patent	O
5	O
,	O
758	O
,	O
352	O
,	O
U.S.	O
patent	O
6,286,013	O
(	O
all	O
expired	O
since	O
2013	O
)	O
.	O
</s>
<s>
On	O
December	O
3	O
,	O
2003	O
,	O
Microsoft	O
announced	O
that	O
it	O
would	O
be	O
offering	O
licenses	O
for	O
use	O
of	O
its	O
FAT	B-Application
specification	I-Application
and	O
"	O
associated	O
intellectual	O
property	O
"	O
,	O
at	O
the	O
cost	O
of	O
a	O
royalty	O
per	O
unit	O
sold	O
,	O
with	O
a	O
maximum	O
royalty	O
per	O
license	O
agreement	O
.	O
</s>
<s>
To	O
this	O
end	O
,	O
Microsoft	O
cited	O
four	O
patents	O
on	O
the	O
FAT	O
file	B-Application
system	I-Application
as	O
the	O
basis	O
of	O
its	O
intellectual	O
property	O
claims	O
.	O
</s>
<s>
In	O
the	O
EFI	B-Architecture
FAT32	B-Application
specification	I-Application
,	O
Microsoft	O
specifically	O
grants	O
a	O
number	O
of	O
rights	O
,	O
which	O
many	O
readers	O
have	O
interpreted	O
as	O
permitting	O
operating	B-General_Concept
system	I-General_Concept
vendors	O
to	O
implement	O
FAT	O
.	O
</s>
<s>
Non-Microsoft	O
patents	O
affecting	O
FAT	O
include	O
:	O
U.S.	O
patent	O
5	O
,	O
367	O
,	O
671	O
,	O
specific	O
to	O
the	O
OS/2	B-Application
extended	O
object	O
attributes	O
(	O
expired	O
in	O
2011	O
)	O
.	O
</s>
<s>
As	O
some	O
TomTom	O
products	O
are	O
based	O
on	O
Linux	B-Application
,	O
this	O
marked	O
the	O
first	O
time	O
that	O
Microsoft	O
tried	O
to	O
enforce	O
its	O
patents	O
against	O
the	O
Linux	B-Application
platform	O
.	O
</s>
<s>
In	O
October	O
2010	O
,	O
Microsoft	O
filed	O
a	O
patent	O
infringement	O
lawsuit	O
against	O
Motorola	O
alleging	O
several	O
patents	O
(	O
including	O
two	O
of	O
the	O
VFAT	O
patents	O
)	O
were	O
not	O
licensed	O
for	O
use	O
in	O
the	O
Android	B-Application
operating	I-Application
system	I-Application
.	O
</s>
