<s>
Windows	B-Device
NT	I-Device
is	O
a	O
proprietary	B-Application
graphical	B-Application
operating	B-General_Concept
system	I-General_Concept
produced	O
by	O
Microsoft	O
,	O
the	O
first	O
version	O
of	O
which	O
was	O
released	O
on	O
July	O
27	O
,	O
1993	O
.	O
</s>
<s>
It	O
is	O
a	O
processor-independent	O
,	O
multiprocessing	B-Operating_System
and	O
multi-user	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
.	O
</s>
<s>
The	O
first	O
version	O
of	O
Windows	B-Device
NT	I-Device
was	O
Windows	B-Device
NT	I-Device
3.1	I-Device
and	O
was	O
produced	O
for	O
workstations	B-Device
and	O
server	B-Application
computers	I-Application
.	O
</s>
<s>
It	O
was	O
a	O
commercially	O
focused	O
operating	B-General_Concept
system	I-General_Concept
intended	O
to	O
complement	O
consumer	O
versions	O
of	O
Windows	B-Application
that	O
were	O
based	O
on	O
MS-DOS	B-Application
(	O
including	O
Windows	B-Application
1.0	I-Application
through	O
Windows	B-Application
3.1x	I-Application
)	O
.	O
</s>
<s>
Gradually	O
,	O
the	O
Windows	B-Device
NT	I-Device
family	I-Device
was	O
expanded	O
into	O
Microsoft	O
's	O
general-purpose	B-General_Concept
operating	I-General_Concept
system	I-General_Concept
product	O
line	O
for	O
all	O
personal	B-Device
computers	I-Device
,	O
deprecating	O
the	O
Windows	B-Application
9x	O
family	O
.	O
</s>
<s>
Starting	O
with	O
Windows	B-Application
2000	I-Application
,	O
"	O
NT	O
"	O
was	O
removed	O
from	O
the	O
product	O
name	O
and	O
is	O
only	O
included	O
in	O
the	O
product	O
version	O
string	O
along	O
with	O
several	O
low-level	O
places	O
within	O
the	O
system	O
.	O
</s>
<s>
NT	O
was	O
the	O
first	O
purely	O
32-bit	O
version	O
of	O
Windows	B-Application
,	O
whereas	O
its	O
consumer-oriented	O
counterparts	O
,	O
Windows	B-Application
3.1x	I-Application
and	O
Windows	B-Application
9x	O
,	O
were	O
16-bit/32	O
-bit	O
hybrids	O
.	O
</s>
<s>
It	O
is	O
a	O
multi-architecture	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
Initially	O
,	O
it	O
supported	O
several	O
instruction	B-General_Concept
set	I-General_Concept
architectures	I-General_Concept
,	O
including	O
IA-32	B-Device
,	O
MIPS	B-Device
,	O
and	O
DEC	B-Device
Alpha	I-Device
;	O
support	O
for	O
PowerPC	B-Architecture
,	O
Itanium	B-General_Concept
,	O
x64	B-Device
,	O
and	O
ARM	B-Architecture
were	O
added	O
later	O
.	O
</s>
<s>
The	O
latest	O
versions	O
support	O
x86	B-Operating_System
(	O
including	O
IA-32	B-Device
and	O
x64	B-Device
)	O
and	O
ARM	B-Architecture
.	O
</s>
<s>
Major	O
features	O
of	O
the	O
Windows	B-Device
NT	I-Device
family	I-Device
include	O
Windows	B-Application
Shell	I-Application
,	O
Windows	B-Library
API	I-Library
,	O
Native	B-Application
API	I-Application
,	O
Active	B-Protocol
Directory	I-Protocol
,	O
Group	O
Policy	O
,	O
Hardware	B-Operating_System
Abstraction	I-Operating_System
Layer	I-Operating_System
,	O
NTFS	B-Application
,	O
BitLocker	O
,	O
Windows	B-Application
Store	I-Application
,	O
Windows	B-Application
Update	O
,	O
and	O
Hyper-V	O
.	O
</s>
<s>
Versions	O
of	O
Windows	B-Device
NT	I-Device
are	O
installed	O
using	O
Windows	B-Application
Setup	O
,	O
which	O
,	O
starting	O
with	O
Windows	B-Application
Vista	I-Application
,	O
uses	O
the	O
Windows	B-Application
Preinstallation	O
Environment	O
,	O
which	O
is	O
a	O
lightweight	O
version	O
of	O
Windows	B-Device
NT	I-Device
made	O
for	O
deployment	O
of	O
the	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
It	O
has	O
been	O
suggested	O
that	O
Dave	O
Cutler	O
intended	O
the	O
initialism	O
"	O
WNT	O
"	O
as	O
a	O
play	O
on	O
VMS	B-Operating_System
,	O
incrementing	O
each	O
letter	O
by	O
one	O
.	O
</s>
<s>
However	O
,	O
the	O
project	O
was	O
originally	O
intended	O
as	O
a	O
follow-on	O
to	O
OS/2	B-Application
and	O
was	O
referred	O
to	O
as	O
"	O
NT	B-Device
OS/2	I-Device
"	O
before	O
receiving	O
the	O
Windows	B-Application
brand	O
.	O
</s>
<s>
One	O
of	O
the	O
original	O
NT	O
developers	O
,	O
Mark	O
Lucovsky	O
,	O
states	O
that	O
the	O
name	O
was	O
taken	O
from	O
the	O
original	O
target	O
processor	O
—	O
the	O
Intel	B-General_Concept
i860	I-General_Concept
,	O
code-named	O
N10	O
(	O
"	O
N-Ten	O
"	O
)	O
.	O
</s>
<s>
The	O
letters	O
were	O
dropped	O
from	O
the	O
names	O
of	O
releases	O
from	O
Windows	B-Application
2000	I-Application
and	O
later	O
,	O
though	O
Microsoft	O
described	O
that	O
product	O
as	O
being	O
"	O
Built	O
on	O
NT	O
Technology	O
"	O
.	O
</s>
<s>
One	O
of	O
the	O
main	O
purposes	O
of	O
NT	O
is	O
hardware	O
and	O
software	B-Architecture
portability	I-Architecture
.	O
</s>
<s>
Various	O
versions	O
of	O
NT	O
family	O
operating	B-General_Concept
systems	I-General_Concept
have	O
been	O
released	O
for	O
a	O
variety	O
of	O
processor	O
architectures	O
,	O
initially	O
IA-32	B-Device
,	O
MIPS	B-Device
,	O
and	O
DEC	B-Device
Alpha	I-Device
,	O
with	O
PowerPC	B-Architecture
,	O
Itanium	B-General_Concept
,	O
x86-64	B-Device
and	O
ARM	B-Architecture
supported	O
in	O
later	O
releases	O
.	O
</s>
<s>
An	O
initial	O
idea	O
was	O
to	O
have	O
a	O
common	O
code	O
base	O
with	O
a	O
custom	O
Hardware	B-Operating_System
Abstraction	I-Operating_System
Layer	I-Operating_System
(	O
HAL	B-Operating_System
)	O
for	O
each	O
platform	O
.	O
</s>
<s>
However	O
,	O
support	O
for	O
MIPS	B-Device
,	O
Alpha	B-Device
,	O
and	O
PowerPC	B-Architecture
was	O
later	O
dropped	O
in	O
Windows	B-Application
2000	I-Application
.	O
</s>
<s>
Broad	O
software	O
compatibility	O
was	O
initially	O
achieved	O
with	O
support	O
for	O
several	O
API	B-Application
"	O
personalities	O
"	O
,	O
including	O
Windows	B-Library
API	I-Library
,	O
POSIX	B-Device
,	O
and	O
OS/2	B-Application
APIs	I-Application
–	O
the	O
latter	O
two	O
were	O
phased	O
out	O
starting	O
with	O
Windows	B-Application
XP	I-Application
.	O
</s>
<s>
Partial	O
MS-DOS	B-Application
and	O
Windows	B-Application
16-bit	O
compatibility	O
is	O
achieved	O
on	O
IA-32	B-Device
via	O
an	O
integrated	O
DOS	O
Virtual	O
Machine	O
–	O
although	O
this	O
feature	O
is	O
not	O
available	O
on	O
other	O
architectures	O
.	O
</s>
<s>
has	O
also	O
supported	O
Windows	B-Application
network	O
protocols	O
,	O
inheriting	O
the	O
previous	O
OS/2	B-Algorithm
LAN	I-Algorithm
Manager	I-Algorithm
networking	O
,	O
as	O
well	O
as	O
TCP/IP	B-Protocol
networking	O
(	O
for	O
which	O
Microsoft	O
used	O
to	O
implement	O
a	O
TCP/IP	B-Protocol
stack	I-Protocol
derived	O
at	O
first	O
from	O
a	O
STREAMS-based	O
stack	O
from	O
Spider	O
Systems	O
,	O
then	O
later	O
rewritten	O
in-house	O
)	O
.	O
</s>
<s>
Windows	B-Device
NT	I-Device
3.1	I-Device
was	O
the	O
first	O
version	O
of	O
Windows	B-Application
to	O
use	O
32-bit	O
flat	O
virtual	O
memory	O
addressing	O
on	O
32-bit	O
processors	O
.	O
</s>
<s>
Its	O
companion	O
product	O
,	O
Windows	B-Application
3.1	I-Application
,	O
used	O
segmented	O
addressing	O
and	O
switches	O
from	O
16-bit	O
to	O
32-bit	O
addressing	O
in	O
pages	O
.	O
</s>
<s>
Windows	B-Device
NT	I-Device
3.1	I-Device
featured	O
a	O
core	O
kernel	B-Operating_System
providing	O
a	O
system	O
API	B-Application
,	O
running	O
in	O
supervisor	O
mode	O
(	O
ring	O
0	O
in	O
x86	B-Operating_System
;	O
referred	O
to	O
in	O
Windows	B-Device
NT	I-Device
as	O
"	O
kernel	B-Operating_System
mode	O
"	O
on	O
all	O
platforms	O
)	O
,	O
and	O
a	O
set	O
of	O
user-space	B-Operating_System
environments	O
with	O
their	O
own	O
APIs	B-Application
which	O
included	O
the	O
new	O
Win32	B-Library
environment	O
,	O
an	O
OS/2	B-Application
1.3	O
text-mode	O
environment	O
and	O
a	O
POSIX	B-Device
environment	O
.	O
</s>
<s>
The	O
full	O
preemptive	O
multitasking	O
kernel	B-Operating_System
could	O
interrupt	O
running	O
tasks	O
to	O
schedule	B-Operating_System
other	O
tasks	O
,	O
without	O
relying	O
on	O
user	O
programs	O
to	O
voluntarily	O
give	O
up	O
control	O
of	O
the	O
CPU	O
,	O
as	O
in	O
Windows	B-Application
3.1	I-Application
Windows	B-Application
applications	I-Application
(	O
although	O
MS-DOS	B-Application
applications	O
were	O
preemptively	O
multitasked	O
in	O
Windows	B-Application
starting	O
with	O
Windows/386	O
)	O
.	O
</s>
<s>
Notably	O
,	O
in	O
Windows	B-Device
NT	I-Device
3.x	O
,	O
several	O
I/O	O
driver	O
subsystems	O
,	O
such	O
as	O
video	O
and	O
printing	O
,	O
were	O
user-mode	B-Operating_System
subsystems	O
.	O
</s>
<s>
In	O
Windows	B-Device
NT	I-Device
4	I-Device
,	O
the	O
video	O
,	O
server	O
,	O
and	O
printer	O
spooler	O
subsystems	O
were	O
moved	O
into	O
kernel	B-Operating_System
mode	O
.	O
</s>
<s>
Windows	B-Device
NT	I-Device
's	O
first	O
GUI	B-Application
was	O
strongly	O
influenced	O
by	O
(	O
and	O
programmatically	O
compatible	O
with	O
)	O
that	O
from	O
Windows	B-Application
3.1	I-Application
;	O
Windows	B-Device
NT	I-Device
4	I-Device
's	O
interface	O
was	O
redesigned	O
to	O
match	O
that	O
of	O
the	O
brand	O
new	O
Windows	B-Application
95	I-Application
,	O
moving	O
from	O
the	O
Program	O
Manager	O
to	O
the	O
Windows	B-Application
shell	I-Application
design	O
.	O
</s>
<s>
NTFS	B-Application
,	O
a	O
journaled	O
,	O
secure	O
file	O
system	O
,	O
is	O
a	O
major	O
feature	O
for	O
NT	O
.	O
</s>
<s>
Windows	B-Device
NT	I-Device
also	O
allows	O
for	O
other	O
installable	O
file	O
systems	O
;	O
since	O
versions	O
3.1	O
,	O
NT	O
may	O
be	O
installed	O
on	O
FAT	B-Application
or	O
HPFS	B-Application
file	O
systems	O
.	O
</s>
<s>
Windows	B-Device
NT	I-Device
introduced	O
its	O
own	O
driver	O
model	O
,	O
the	O
Windows	B-Device
NT	I-Device
driver	O
model	O
,	O
and	O
is	O
incompatible	O
with	O
older	O
driver	O
frameworks	O
.	O
</s>
<s>
With	O
Windows	B-Application
2000	I-Application
,	O
the	O
Windows	B-Device
NT	I-Device
driver	O
model	O
was	O
enhanced	O
to	O
become	O
the	O
Windows	B-Application
Driver	I-Application
Model	I-Application
,	O
which	O
was	O
first	O
introduced	O
with	O
Windows	B-Device
98	I-Device
,	O
but	O
was	O
based	O
on	O
the	O
NT	O
driver	O
model	O
.	O
</s>
<s>
Windows	B-Application
Vista	I-Application
added	O
native	O
support	O
for	O
the	O
Windows	B-Application
Driver	I-Application
Foundation	I-Application
,	O
which	O
is	O
also	O
available	O
for	O
Windows	B-Application
XP	I-Application
,	O
Windows	B-Application
Server	I-Application
2003	I-Application
and	O
to	O
an	O
extent	O
,	O
Windows	B-Application
2000	I-Application
.	O
</s>
<s>
Microsoft	O
decided	O
to	O
create	O
a	O
portable	O
operating	B-General_Concept
system	I-General_Concept
,	O
compatible	O
with	O
OS/2	B-Application
and	O
POSIX	B-Device
and	O
supporting	O
multiprocessing	B-Operating_System
,	O
in	O
October	O
1988	O
.	O
</s>
<s>
When	O
development	O
started	O
in	O
November	O
1989	O
,	O
Windows	B-Device
NT	I-Device
was	O
to	O
be	O
known	O
as	O
OS/2	B-Application
3.0	O
,	O
the	O
third	O
version	O
of	O
the	O
operating	B-General_Concept
system	I-General_Concept
developed	O
jointly	O
by	O
Microsoft	O
and	O
IBM	O
.	O
</s>
<s>
To	O
ensure	O
portability	B-Architecture
,	O
initial	O
development	O
was	O
targeted	O
at	O
the	O
Intel	O
i860XR	O
RISC	B-Architecture
processor	I-Architecture
,	O
switching	O
to	O
the	O
MIPS	B-Device
R3000	I-Device
in	O
late	O
1989	O
,	O
and	O
then	O
the	O
Intel	B-General_Concept
i386	I-General_Concept
in	O
1990	O
.	O
</s>
<s>
Microsoft	O
also	O
continued	O
parallel	O
development	O
of	O
the	O
DOS-based	O
and	O
less	O
resource-demanding	O
Windows	B-Application
environment	O
,	O
resulting	O
in	O
the	O
release	O
of	O
Windows	B-Application
3.0	I-Application
in	O
May	O
1990	O
.	O
</s>
<s>
Windows	B-Application
3.0	I-Application
was	O
eventually	O
so	O
successful	O
that	O
Microsoft	O
decided	O
to	O
change	O
the	O
primary	O
application	B-Application
programming	I-Application
interface	I-Application
for	O
the	O
still	O
unreleased	O
NT	B-Device
OS/2	I-Device
(	O
as	O
it	O
was	O
then	O
known	O
)	O
from	O
an	O
extended	O
OS/2	B-Application
API	I-Application
to	O
an	O
extended	O
Windows	B-Library
API	I-Library
.	O
</s>
<s>
IBM	O
continued	O
OS/2	B-Application
development	O
alone	O
while	O
Microsoft	O
continued	O
work	O
on	O
the	O
newly	O
renamed	O
Windows	B-Device
NT	I-Device
.	O
</s>
<s>
Though	O
neither	O
operating	B-General_Concept
system	I-General_Concept
would	O
immediately	O
be	O
as	O
popular	O
as	O
Microsoft	O
's	O
MS-DOS	B-Application
or	O
Windows	B-Application
products	O
,	O
Windows	B-Device
NT	I-Device
would	O
eventually	O
be	O
far	O
more	O
successful	O
than	O
OS/2	B-Application
.	O
</s>
<s>
Microsoft	O
hired	O
a	O
group	O
of	O
developers	O
from	O
Digital	O
Equipment	O
Corporation	O
led	O
by	O
Dave	O
Cutler	O
to	O
build	O
Windows	B-Device
NT	I-Device
,	O
and	O
many	O
elements	O
of	O
the	O
design	O
reflect	O
earlier	O
DEC	O
experience	O
with	O
Cutler	O
's	O
VMS	B-Operating_System
,	O
VAXELN	B-Operating_System
and	O
RSX-11	B-Application
,	O
but	O
also	O
an	O
unreleased	O
object-based	O
operating	B-General_Concept
system	I-General_Concept
developed	O
by	O
Cutler	O
at	O
Digital	O
codenamed	O
MICA	B-Operating_System
.	O
</s>
<s>
The	O
team	O
was	O
joined	O
by	O
selected	O
members	O
of	O
the	O
disbanded	O
OS/2	B-Application
team	O
,	O
including	O
Moshe	O
Dunie	O
.	O
</s>
<s>
The	O
VMS	B-Operating_System
kernel	B-Operating_System
was	O
primarily	O
written	O
in	O
VAX	B-Language
MACRO	I-Language
,	O
but	O
Windows	B-Device
NT	I-Device
was	O
designed	O
to	O
run	O
on	O
multiple	O
instruction	B-General_Concept
set	I-General_Concept
architectures	I-General_Concept
and	O
multiple	O
hardware	O
platforms	O
within	O
each	O
architecture	B-Architecture
.	O
</s>
<s>
The	O
platform	O
dependencies	O
are	O
hidden	O
from	O
the	O
rest	O
of	O
the	O
system	O
by	O
the	O
HAL	B-Operating_System
(	O
Hardware	B-Operating_System
Abstraction	I-Operating_System
Layer	I-Operating_System
)	O
.	O
</s>
<s>
While	O
creating	O
Windows	B-Device
NT	I-Device
,	O
Microsoft	O
developers	O
rewrote	O
VMS	B-Operating_System
in	O
C	B-Language
.	O
Although	O
they	O
added	O
the	O
Win32	B-Library
API	I-Library
,	O
NTFS	B-Application
file	I-Application
system	I-Application
,	O
GUI	B-Application
,	O
and	O
backwards	O
compatibility	O
with	O
DOS	O
,	O
OS/2	B-Application
,	O
and	O
Win16	B-Library
,	O
DEC	O
engineers	O
almost	O
immediately	O
noticed	O
the	O
two	O
operating	B-General_Concept
systems	I-General_Concept
 '	O
internal	O
similarities	O
;	O
parts	O
of	O
VAX/VMS	B-Operating_System
Internals	O
and	O
Data	O
Structures	O
,	O
published	O
by	O
Digital	O
Press	O
,	O
accurately	O
describe	O
Windows	B-Device
NT	I-Device
internals	O
using	O
VMS	B-Operating_System
terms	O
.	O
</s>
<s>
Instead	O
of	O
a	O
lawsuit	O
,	O
Microsoft	O
agreed	O
to	O
pay	O
DEC	O
$65	O
–	O
100	O
million	O
,	O
help	O
market	O
VMS	B-Operating_System
,	O
train	O
Digital	O
personnel	O
on	O
Windows	B-Device
NT	I-Device
,	O
and	O
continue	O
Windows	B-Device
NT	I-Device
support	O
for	O
the	O
DEC	B-Device
Alpha	I-Device
.	O
</s>
<s>
Windows	B-Device
NT	I-Device
and	O
VMS	B-Operating_System
memory	B-General_Concept
management	I-General_Concept
,	O
processes	O
,	O
and	O
scheduling	O
are	O
very	O
similar	O
.	O
</s>
<s>
Windows	B-Device
NT	I-Device
's	O
process	B-Operating_System
management	I-Operating_System
differs	O
by	O
implementing	O
threading	B-Operating_System
,	O
which	O
DEC	O
did	O
not	O
implement	O
until	O
VMS	B-Operating_System
7.0	O
in	O
1995	O
,	O
likely	O
to	O
compete	O
with	O
Microsoft	O
.	O
</s>
<s>
Like	O
VMS	B-Operating_System
,	O
Windows	B-Device
NT	I-Device
's	O
kernel	B-Operating_System
mode	O
code	O
distinguishes	O
between	O
the	O
"	O
kernel	B-Operating_System
"	O
,	O
whose	O
primary	O
purpose	O
is	O
to	O
implement	O
processor	O
-	O
and	O
architecture-dependent	O
functions	O
,	O
and	O
the	O
"	O
executive	O
"	O
.	O
</s>
<s>
This	O
was	O
designed	O
as	O
a	O
modified	O
microkernel	B-Operating_System
,	O
as	O
the	O
Windows	B-Device
NT	I-Device
kernel	B-Operating_System
was	O
influenced	O
by	O
the	O
Mach	B-Operating_System
microkernel	I-Operating_System
developed	O
by	O
Richard	O
Rashid	O
at	O
Carnegie	O
Mellon	O
University	O
,	O
but	O
does	O
not	O
meet	O
all	O
of	O
the	O
criteria	O
of	O
a	O
pure	O
microkernel	B-Operating_System
.	O
</s>
<s>
Both	O
the	O
kernel	B-Operating_System
and	O
the	O
executive	O
are	O
linked	B-Application
together	O
into	O
the	O
single	O
loaded	O
module	O
ntoskrnl.exe	O
;	O
from	O
outside	O
this	O
module	O
,	O
there	O
is	O
little	O
distinction	O
between	O
the	O
kernel	B-Operating_System
and	O
the	O
executive	O
.	O
</s>
<s>
Routines	O
from	O
each	O
are	O
directly	O
accessible	O
,	O
as	O
for	O
example	O
from	O
kernel-mode	O
device	O
drivers	O
.	O
</s>
<s>
API	B-Application
sets	O
in	O
the	O
Windows	B-Device
NT	I-Device
family	I-Device
are	O
implemented	O
as	O
subsystems	O
atop	O
the	O
publicly	O
undocumented	O
"	B-Application
native	I-Application
"	I-Application
API	I-Application
;	O
this	O
allowed	O
the	O
late	O
adoption	O
of	O
the	O
Windows	B-Library
API	I-Library
(	O
into	O
the	O
Win32	B-Library
subsystem	O
)	O
.	O
</s>
<s>
Windows	B-Device
NT	I-Device
was	O
one	O
of	O
the	O
earliest	O
operating	B-General_Concept
systems	I-General_Concept
to	O
use	O
Unicode	O
internally	O
.	O
</s>
<s>
Windows	B-Device
NT	I-Device
uses	O
a	O
layered	O
design	O
architecture	B-Architecture
that	O
consists	O
of	O
two	O
main	O
components	O
,	O
user	B-Operating_System
mode	I-Operating_System
and	O
kernel	B-Operating_System
mode	O
.	O
</s>
<s>
Programs	O
and	O
subsystems	O
in	O
user	B-Operating_System
mode	I-Operating_System
are	O
limited	O
in	O
terms	O
of	O
what	O
system	B-General_Concept
resources	I-General_Concept
they	O
have	O
access	O
to	O
,	O
while	O
the	O
kernel	B-Operating_System
mode	O
has	O
unrestricted	O
access	O
to	O
the	O
system	O
memory	O
and	O
external	O
devices	O
.	O
</s>
<s>
Kernel	B-Operating_System
mode	O
in	O
Windows	B-Device
NT	I-Device
has	O
full	O
access	O
to	O
the	O
hardware	O
and	O
system	B-General_Concept
resources	I-General_Concept
of	O
the	O
computer	O
.	O
</s>
<s>
The	O
Windows	B-Device
NT	I-Device
kernel	B-Operating_System
is	O
a	O
hybrid	B-Operating_System
kernel	I-Operating_System
;	O
the	O
architecture	B-Architecture
comprises	O
a	O
simple	O
kernel	B-Operating_System
,	O
hardware	B-Operating_System
abstraction	I-Operating_System
layer	I-Operating_System
(	O
HAL	B-Operating_System
)	O
,	O
drivers	O
,	O
and	O
a	O
range	O
of	O
services	O
(	O
collectively	O
named	O
Executive	O
)	O
,	O
which	O
all	O
exist	O
in	O
kernel	B-Operating_System
mode	O
.	O
</s>
<s>
The	O
booting	O
process	B-Operating_System
of	O
Windows	B-Device
NT	I-Device
begins	O
with	O
NTLDR	B-Application
in	O
versions	O
before	O
Vista	B-Application
and	O
the	O
Windows	B-Operating_System
Boot	I-Operating_System
Manager	I-Operating_System
in	O
Vista	B-Application
and	O
later	O
.	O
</s>
<s>
The	O
boot	O
loader	O
is	O
responsible	O
for	O
accessing	O
the	O
file	O
system	O
on	O
the	O
boot	O
drive	O
,	O
starting	O
the	O
kernel	B-Operating_System
,	O
and	O
loading	O
boot-time	O
device	O
drivers	O
into	O
memory	O
.	O
</s>
<s>
Once	O
all	O
the	O
boot	O
and	O
system	O
drivers	O
have	O
been	O
loaded	O
,	O
the	O
kernel	B-Operating_System
starts	O
the	O
Session	O
Manager	O
Sybsystem	O
.	O
</s>
<s>
This	O
process	B-Operating_System
launches	O
winlogon	O
,	O
which	O
allows	O
the	O
user	O
to	O
login	O
.	O
</s>
<s>
Once	O
the	O
user	O
is	O
logged	O
in	O
File	B-Protocol
Explorer	I-Protocol
is	O
started	O
,	O
loading	O
the	O
graphical	B-Application
user	I-Application
interface	I-Application
of	O
Windows	B-Device
NT	I-Device
.	O
</s>
<s>
Windows	B-Device
NT	I-Device
is	O
written	O
in	O
C	B-Language
and	O
C++	B-Language
,	O
with	O
a	O
very	O
small	O
amount	O
written	O
in	O
assembly	B-Language
language	I-Language
.	O
</s>
<s>
C	B-Language
is	O
mostly	O
used	O
for	O
the	O
kernel	B-Operating_System
code	O
while	O
C++	B-Language
is	O
mostly	O
used	O
for	O
user-mode	B-Operating_System
code	O
.	O
</s>
<s>
Assembly	B-Language
language	I-Language
is	O
avoided	O
where	O
possible	O
because	O
it	O
would	O
impede	O
portability	B-Architecture
.	O
</s>
<s>
+	O
Windows	B-Device
NT	I-Device
releases	O
Version	O
Marketing	O
name	O
Editions	O
Release	O
date	O
Build	O
number	O
3.1	O
Windows	B-Device
NT	I-Device
3.1	I-Device
Workstation	B-Device
(	O
named	O
just	O
Windows	B-Device
NT	I-Device
)	O
,	O
Advanced	O
Server	O
July	O
27	O
,	O
1993	O
528	O
3.5	O
Windows	B-Device
NT	I-Device
3.5	I-Device
Workstation	B-Device
,	O
Server	O
September	O
21	O
,	O
1994	O
807	O
3.51	O
Windows	B-Device
NT	I-Device
3.51	I-Device
May	O
30	O
,	O
1995	O
1057	O
4.0	O
Windows	B-Device
NT	I-Device
4.0	I-Device
Workstation	B-Device
,	O
Server	O
,	O
Enterprise	B-Application
Server	I-Application
,	O
Terminal	O
Server	O
,	O
Embedded	O
August	O
24	O
,	O
1996	O
1381	O
5.0	O
Windows	B-Application
2000	I-Application
Professional	O
,	O
Server	O
,	O
Advanced	O
Server	O
February	O
17	O
,	O
2000	O
2195	O
Datacenter	O
Server	O
September	O
26	O
,	O
2000	O
5.1	O
Windows	B-Application
XP	I-Application
Home	O
,	O
Professional	O
,	O
Media	B-Application
Center	I-Application
(	O
original	O
,	O
2004	O
&	O
2005	O
)	O
,	O
Tablet	O
PC	O
(	O
original	O
and	O
2005	O
)	O
,	O
Starter	O
,	O
Embedded	O
,	O
Home	O
N	O
,	O
Professional	O
N	O
October	O
25	O
,	O
2001	O
2600	O
Windows	B-Device
Fundamentals	I-Device
for	I-Device
Legacy	I-Device
PCs	I-Device
July	O
8	O
,	O
2006	O
5.2	O
Windows	B-Application
XP	I-Application
64-bit	B-Device
Edition	O
Version	O
2003	O
(	O
IA-64	B-General_Concept
)	O
March	O
28	O
,	O
2003	O
3790	O
Windows	B-Application
Server	I-Application
2003	I-Application
Standard	O
,	O
Enterprise	O
,	O
Datacenter	O
,	O
Web	O
,	O
Storage	O
,	O
Small	O
Business	O
Server	O
,	O
Compute	O
Cluster	O
April	O
24	O
,	O
2003	O
Windows	B-Application
XP	I-Application
Professional	B-Operating_System
x64	I-Operating_System
Edition	I-Operating_System
(	O
x86-64	B-Device
)	O
April	O
25	O
,	O
2005	O
Windows	B-Application
Server	I-Application
2003	I-Application
R2	O
Standard	O
,	O
Enterprise	O
,	O
Datacenter	O
,	O
Web	O
,	O
Storage	O
,	O
Small	O
Business	O
Server	O
,	O
Compute	O
Cluster	O
December	O
6	O
,	O
2005	O
Windows	B-Application
Home	I-Application
Server	I-Application
November	O
4	O
,	O
2007	O
6.0	O
Windows	B-Application
Vista	I-Application
Starter	O
,	O
Home	O
Basic	O
,	O
Home	O
Premium	O
,	O
Business	O
,	O
Enterprise	O
,	O
Ultimate	O
Windows	B-Device
Server	I-Device
2008	I-Device
Foundation	O
,	O
Standard	O
,	O
Enterprise	O
,	O
Datacenter	O
,	O
Web	O
Server	O
,	O
HPC	O
Server	O
,	O
Itanium-Based	O
Systems	O
February	O
27	O
,	O
2008	O
6.1	O
Windows	B-Device
7	I-Device
Starter	O
,	O
Home	O
Basic	O
,	O
Home	O
Premium	O
,	O
Professional	O
,	O
Enterprise	O
,	O
Ultimate	O
October	O
22	O
,	O
2009	O
Windows	B-Device
Server	I-Device
2008	I-Device
R2	I-Device
Foundation	O
,	O
Standard	O
,	O
Enterprise	O
,	O
Datacenter	O
,	O
Web	O
Server	O
,	O
HPC	O
Server	O
,	O
Itanium-Based	O
Systems	O
Windows	B-Application
Home	I-Application
Server	I-Application
2011	O
Home	O
Server	O
Premium	O
April	O
6	O
,	O
2011	O
7601	O
(	O
SP1	O
)	O
Windows	B-Application
Thin	O
PC	O
June	O
6	O
,	O
2011	O
6.2	O
Windows	B-Application
8	I-Application
Windows	B-Application
8	I-Application
,	O
Windows	B-Application
8	I-Application
Pro	O
,	O
Windows	B-Application
8	I-Application
Enterprise	O
,	O
Windows	B-Operating_System
RT	I-Operating_System
October	O
26	O
,	O
2012	O
9200	O
Windows	B-Device
Server	I-Device
2012	I-Device
.	O
</s>
<s>
Windows	B-Device
NT	I-Device
3.1	I-Device
to	O
3.51	O
incorporated	O
the	O
Program	O
Manager	O
and	O
File	B-Application
Manager	I-Application
from	O
the	O
Windows	B-Application
3.1x	I-Application
series	O
.	O
</s>
<s>
Windows	B-Device
NT	I-Device
4.0	I-Device
onwards	O
replaced	O
those	O
programs	O
with	O
Windows	B-Protocol
Explorer	I-Protocol
(	O
including	O
a	O
taskbar	O
and	O
Start	O
menu	O
)	O
,	O
which	O
originally	O
appeared	O
in	O
Windows	B-Application
95	I-Application
.	O
</s>
<s>
The	O
first	O
release	O
was	O
given	O
version	O
number	O
3.1	O
to	O
match	O
the	O
contemporary	O
16-bit	B-Library
Windows	I-Library
;	O
magazines	O
of	O
that	O
era	O
claimed	O
the	O
number	O
was	O
also	O
used	O
to	O
make	O
that	O
version	O
seem	O
more	O
reliable	O
than	O
a	O
"	O
.0	O
"	O
release	O
.	O
</s>
<s>
Also	O
the	O
Novell	O
IPX	O
protocol	O
was	O
apparently	O
licensed	O
only	O
to	O
3.1	O
versions	O
of	O
Windows	B-Application
software	O
.	O
</s>
<s>
The	O
NT	O
version	O
number	O
is	O
not	O
now	O
generally	O
used	O
for	O
marketing	O
purposes	O
,	O
but	O
is	O
still	O
used	O
internally	O
,	O
and	O
said	O
to	O
reflect	O
the	O
degree	O
of	O
changes	O
to	O
the	O
core	O
of	O
the	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
However	O
,	O
for	O
application	O
compatibility	O
reasons	O
,	O
Microsoft	O
kept	O
the	O
major	O
version	O
number	O
as	O
6	O
in	O
releases	O
following	O
Vista	B-Application
,	O
but	O
changed	O
it	O
later	O
to	O
10	O
in	O
Windows	B-Operating_System
10	I-Operating_System
.	O
</s>
<s>
Starting	O
with	O
Windows	B-Device
8.1	I-Device
,	O
Microsoft	O
changed	O
the	O
Version	O
API	B-Application
Helper	O
functions	O
 '	O
behavior	O
.	O
</s>
<s>
If	O
an	O
application	O
is	O
not	O
manifested	O
for	O
Windows	B-Device
8.1	I-Device
or	O
later	O
,	O
the	O
API	B-Application
will	O
always	O
return	O
version	O
6.2	O
,	O
which	O
is	O
the	O
version	O
number	O
of	O
Windows	B-Application
8	I-Application
.	O
</s>
<s>
This	O
is	O
because	O
the	O
manifest	O
feature	O
was	O
introduced	O
with	O
Windows	B-Device
8.1	I-Device
,	O
to	O
replace	O
GetVersion	O
and	O
related	O
functions	O
.	O
</s>
<s>
In	O
order	O
to	O
prevent	O
Intel	O
x86-specific	O
code	O
from	O
slipping	O
into	O
the	O
operating	B-General_Concept
system	I-General_Concept
,	O
due	O
to	O
developers	O
being	O
used	O
to	O
developing	O
on	O
x86	B-Operating_System
chips	O
,	O
Windows	B-Device
NT	I-Device
3.1	I-Device
was	O
initially	O
developed	O
using	O
non-x86	O
development	O
systems	O
and	O
then	O
ported	O
to	O
the	O
x86	B-Operating_System
architecture	I-Operating_System
.	O
</s>
<s>
This	O
work	O
was	O
initially	O
based	O
on	O
the	O
Intel	O
i860-based	O
Dazzle	O
system	O
and	O
,	O
later	O
,	O
the	O
MIPS	B-Device
R4000-based	O
Jazz	B-Device
platform	O
.	O
</s>
<s>
Windows	B-Device
NT	I-Device
3.1	I-Device
was	O
released	O
for	O
Intel	B-Operating_System
x86	I-Operating_System
PC	O
compatible	O
,	O
PC-98	B-Operating_System
,	O
DEC	B-Device
Alpha	I-Device
,	O
and	O
ARC-compliant	O
MIPS	B-Device
platforms	O
.	O
</s>
<s>
Windows	B-Device
NT	I-Device
3.51	I-Device
added	O
support	O
for	O
the	O
PowerPC	B-Architecture
processor	I-Architecture
in	O
1995	O
,	O
specifically	O
PReP-compliant	O
systems	O
such	O
as	O
the	O
IBM	B-Device
ThinkPad	I-Device
Power	I-Device
Series	I-Device
laptops	O
and	O
Motorola	O
PowerStack	O
series	O
;	O
but	O
despite	O
meetings	O
between	O
Michael	O
Spindler	O
and	O
Bill	O
Gates	O
,	O
not	O
on	O
the	O
Power	B-Device
Macintosh	I-Device
as	O
the	O
PReP	B-Device
compliant	O
Power	B-Device
Macintosh	I-Device
project	O
failed	O
to	O
ship	O
.	O
</s>
<s>
Intergraph	O
Corporation	O
ported	O
Windows	B-Device
NT	I-Device
to	O
its	O
Clipper	B-General_Concept
architecture	I-General_Concept
and	O
later	O
announced	O
an	O
intention	O
to	O
port	O
Windows	B-Device
NT	I-Device
3.51	I-Device
to	O
Sun	O
Microsystems	O
 '	O
SPARC	B-Architecture
architecture	B-Architecture
,	O
in	O
conjunction	O
with	O
the	O
company	O
's	O
planned	O
introduction	O
of	O
UltraSPARC	O
models	O
in	O
1995	O
,	O
but	O
neither	O
version	O
was	O
sold	O
to	O
the	O
public	O
as	O
a	O
retail	O
product	O
.	O
</s>
<s>
Only	O
two	O
of	O
the	O
Windows	B-Device
NT	I-Device
4.0	I-Device
variants	O
(	O
IA-32	B-Device
and	O
Alpha	B-Device
)	O
have	O
a	O
full	O
set	O
of	O
service	O
packs	O
available	O
.	O
</s>
<s>
Windows	B-Device
NT	I-Device
4.0	I-Device
was	O
the	O
last	O
major	O
release	O
to	O
support	O
Alpha	B-Device
,	O
MIPS	B-Device
,	O
or	O
PowerPC	B-Architecture
,	O
though	O
development	O
of	O
Windows	B-Application
2000	I-Application
for	O
Alpha	B-Device
continued	O
until	O
August	O
1999	O
,	O
when	O
Compaq	O
stopped	O
support	O
for	O
Windows	B-Device
NT	I-Device
on	O
that	O
architecture	B-Architecture
;	O
and	O
then	O
three	O
days	O
later	O
Microsoft	O
also	O
canceled	O
their	O
AlphaNT	O
program	O
,	O
</s>
<s>
even	O
though	O
the	O
Alpha	B-Device
NT	O
5	O
(	O
Windows	B-Application
2000	I-Application
)	O
release	O
had	O
reached	O
RC1	O
status	O
.	O
</s>
<s>
On	O
January	O
5	O
,	O
2011	O
,	O
Microsoft	O
announced	O
that	O
the	O
next	O
major	O
version	O
of	O
the	O
Windows	B-Device
NT	I-Device
family	I-Device
will	O
include	O
support	O
for	O
the	O
ARM	B-Architecture
architecture	I-Architecture
.	O
</s>
<s>
Microsoft	O
demonstrated	O
a	O
preliminary	O
version	O
of	O
Windows	B-Application
(	O
version	O
6.2.7867	O
)	O
running	O
on	O
an	O
ARM-based	O
computer	O
at	O
the	O
2011	O
Consumer	O
Electronics	O
Show	O
.	O
</s>
<s>
This	O
eventually	O
led	O
to	O
the	O
commercial	O
release	O
of	O
the	O
Windows	B-Application
8-derived	O
Windows	B-Operating_System
RT	I-Operating_System
on	O
October	O
26	O
,	O
2012	O
,	O
and	O
the	O
implementation	O
of	O
NT	O
over	O
CE	O
on	O
Windows	B-Application
Phone	O
8	O
.	O
</s>
<s>
According	O
to	O
Microsoft	O
,	O
it	O
is	O
a	O
common	O
misconception	O
that	O
the	O
Xbox	B-Device
and	O
Xbox	B-Operating_System
360	I-Operating_System
use	O
a	O
modified	O
Windows	B-Application
2000	I-Application
kernel	B-Operating_System
.	O
</s>
<s>
In	O
reality	O
,	O
the	O
Xbox	B-Device
operating	B-General_Concept
system	I-General_Concept
was	O
built	O
from	O
scratch	O
but	O
implements	O
a	O
subset	O
of	O
Windows	B-Library
APIs	I-Library
.	O
</s>
<s>
The	B-Device
Xbox	I-Device
One	I-Device
,	O
and	O
Xbox	B-Device
Series	I-Device
X/S	I-Device
,	O
however	O
,	O
do	O
use	O
a	O
modified	O
version	O
of	O
Windows	B-Operating_System
10	I-Operating_System
.	O
</s>
<s>
Windows	B-Application
11	I-Application
is	O
the	O
first	O
non-server	O
version	O
of	O
Windows	B-Device
NT	I-Device
to	O
not	O
support	O
32-bit	O
platforms	O
.	O
</s>
<s>
The	O
64-bit	B-Device
versions	O
of	O
Windows	B-Device
NT	I-Device
were	O
originally	O
intended	O
to	O
run	O
on	O
Itanium	B-General_Concept
and	O
DEC	B-Device
Alpha	I-Device
;	O
the	O
latter	O
was	O
used	O
internally	O
at	O
Microsoft	O
during	O
early	O
development	O
of	O
64-bit	B-Device
Windows	B-Application
.	O
</s>
<s>
This	O
continued	O
for	O
some	O
time	O
after	O
Microsoft	O
publicly	O
announced	O
that	O
it	O
was	O
cancelling	O
plans	O
to	O
ship	O
64-bit	B-Device
Windows	B-Application
for	O
Alpha	B-Device
.	O
</s>
<s>
Because	O
of	O
this	O
,	O
Alpha	B-Device
versions	O
of	O
Windows	B-Device
NT	I-Device
are	O
32-bit	O
only	O
.	O
</s>
<s>
While	O
Windows	B-Application
2000	I-Application
only	O
supports	O
Intel	B-Device
IA-32	I-Device
(	O
32-bit	O
)	O
,	O
Windows	B-Application
XP	I-Application
,	O
Server	O
2003	O
,	O
Server	B-Device
2008	I-Device
and	O
Server	B-Device
2008	I-Device
R2	I-Device
each	O
have	O
one	O
edition	O
dedicated	O
to	O
Itanium-based	O
systems	O
.	O
</s>
<s>
In	O
comparison	O
with	O
Itanium	B-General_Concept
,	O
Microsoft	O
adopted	O
x64	B-Device
on	O
a	O
greater	O
scale	O
:	O
every	O
version	O
of	O
Windows	B-Application
since	O
Windows	B-Application
XP	I-Application
(	O
which	O
has	O
a	O
dedicated	B-Operating_System
x64	I-Operating_System
edition	I-Operating_System
)	O
has	O
x64	B-Device
editions	I-Device
.	O
</s>
<s>
Windows	B-Operating_System
10	I-Operating_System
version	O
1709	O
onwards	O
supports	O
ARM64	B-Architecture
devices	O
with	O
Qualcomm	O
processors	O
.	O
</s>
<s>
This	O
is	O
a	O
full	O
version	O
of	O
Windows	B-Application
,	O
rather	O
than	O
the	O
cut-down	O
Windows	B-Operating_System
RT	I-Operating_System
.	O
</s>
<s>
The	O
minimum	O
hardware	O
specification	O
required	O
to	O
run	O
each	O
release	O
of	O
the	O
professional	O
workstation	B-Device
version	O
of	O
Windows	B-Device
NT	I-Device
has	O
been	O
fairly	O
slow-moving	O
until	O
the	O
6.0	O
Vista	B-Application
release	O
,	O
which	O
requires	O
a	O
minimum	O
of	O
15	O
GB	O
of	O
free	O
disk	O
space	O
,	O
a	O
10-fold	O
increase	O
in	O
free	O
disk	O
space	O
alone	O
over	O
the	O
previous	O
version	O
.	O
</s>
