<s>
Address	B-Device
Windowing	I-Device
Extensions	I-Device
(	O
AWE	B-Device
)	O
is	O
a	O
Microsoft	B-Application
Windows	I-Application
application	B-Application
programming	I-Application
interface	I-Application
that	O
allows	O
a	O
32-bit	O
software	B-Application
application	I-Application
to	O
access	O
more	O
physical	B-Architecture
memory	I-Architecture
than	O
it	O
has	O
virtual	O
address	O
space	O
,	O
even	O
in	O
excess	O
of	O
the	O
4	O
GB	O
limit	O
.	O
</s>
<s>
The	O
process	O
of	O
mapping	O
an	O
application	B-Application
's	O
virtual	O
address	O
space	O
to	O
physical	B-Architecture
memory	I-Architecture
under	O
AWE	B-Device
is	O
known	O
as	O
"	O
windowing	O
"	O
,	O
and	O
is	O
similar	O
to	O
the	O
overlay	B-General_Concept
concept	O
of	O
other	O
environments	O
.	O
</s>
<s>
AWE	B-Device
is	O
beneficial	O
to	O
certain	O
data-intensive	O
applications	O
,	O
such	O
as	O
database	O
management	O
systems	O
and	O
scientific	O
and	O
engineering	O
software	O
,	O
that	O
need	O
to	O
manipulate	O
very	O
large	O
data	B-General_Concept
sets	I-General_Concept
while	O
minimizing	O
paging	B-Architecture
.	O
</s>
<s>
The	O
application	B-Application
reserves	O
a	O
region	O
,	O
or	O
"	O
window	O
"	O
of	O
virtual	O
address	O
space	O
,	O
and	O
allocates	O
one	O
or	O
more	O
regions	O
of	O
physical	B-Architecture
memory	I-Architecture
.	O
</s>
<s>
Using	O
the	O
AWE	B-Device
API	B-Application
,	O
the	O
application	B-Application
can	O
map	O
the	O
virtual	O
window	O
to	O
any	O
one	O
of	O
the	O
physical	O
regions	O
.	O
</s>
<s>
The	O
application	B-Application
can	O
reserve	O
more	O
than	O
one	O
virtual	O
address	O
space	O
and	O
map	O
it	O
to	O
any	O
of	O
the	O
allocated	O
regions	O
of	O
physical	B-Architecture
memory	I-Architecture
,	O
as	O
long	O
as	O
the	O
number	O
of	O
bytes	O
reserved	O
in	O
the	O
virtual	O
address	O
space	O
matches	O
that	O
of	O
the	O
physical	B-Architecture
memory	I-Architecture
region	O
.	O
</s>
<s>
An	O
application	B-Application
must	O
have	O
the	O
Lock	O
Pages	O
in	O
Memory	O
privilege	O
to	O
use	O
AWE	B-Device
.	O
</s>
<s>
On	O
32-bit	O
systems	O
,	O
AWE	B-Device
depends	O
on	O
Physical	B-General_Concept
Address	I-General_Concept
Extension	I-General_Concept
support	O
when	O
reserving	O
memory	O
above	O
4	O
GB	O
.	O
</s>
<s>
AWE	B-Device
was	O
first	O
introduced	O
in	O
Windows	B-Application
2000	I-Application
as	O
a	O
new	O
API	B-Application
superseding	O
the	O
PSE36	B-General_Concept
method	O
(	O
from	O
the	O
Windows	B-Device
NT	I-Device
4.0	I-Device
Enterprise	O
Edition	O
)	O
of	O
accessing	O
more	O
than	O
4	O
GB	O
of	O
memory	O
,	O
which	O
was	O
no	O
longer	O
supported	O
in	O
Windows	B-Application
2000	I-Application
.	O
</s>
<s>
Among	O
the	O
first	O
applications	O
to	O
make	O
use	O
of	O
AWE	B-Device
were	O
Oracle	B-General_Concept
8.1.6	O
and	O
Microsoft	B-Application
SQL	I-Application
Server	I-Application
2000	O
.	O
</s>
<s>
If	O
the	O
boot	O
flag	O
is	O
used	O
to	O
repartition	O
the	O
32-bit	O
virtual	O
address	O
space	O
(	O
from	O
the	O
2	O
GB	O
kernel	O
and	O
2	O
GB	O
userland	O
)	O
to	O
3	O
GB	O
userland	O
,	O
then	O
AWE	B-Device
is	O
limited	O
to	O
accessing	O
16	O
GB	O
of	O
physical	B-Architecture
memory	I-Architecture
.	O
</s>
<s>
Additional	O
restrictions	O
on	O
the	O
maximum	O
amount	O
of	O
memory	O
addressable	O
thorough	O
AWE	B-Device
are	O
imposed	O
by	O
the	O
Windows	O
licensing	O
scheme	O
.	O
</s>
<s>
For	O
example	O
,	O
Windows	B-Application
2000	I-Application
Advanced	O
Server	O
was	O
limited	O
to	O
8	O
GB	O
,	O
while	O
Windows	B-Application
2000	I-Application
Data	O
Center	O
Server	O
supported	O
64	O
GB	O
.	O
</s>
<s>
An	O
article	O
published	O
in	O
Dr.	O
Dobb	O
's	O
Journal	O
in	O
2004	O
noted	O
that	O
memory	O
allocated	O
using	O
Address	B-Device
Windowing	I-Device
Extensions	I-Device
will	O
not	O
be	O
written	O
to	O
the	O
pagefile	B-Architecture
,	O
and	O
suggested	O
that	O
AWE	B-Device
regions	O
could	O
therefore	O
be	O
used	O
as	O
a	O
way	O
of	O
protecting	O
sensitive	O
application	B-Application
data	O
such	O
as	O
encryption	O
keys	O
.	O
</s>
