<s>
Microsoft	B-Operating_System
Windows	I-Operating_System
XP	I-Operating_System
Professional	I-Operating_System
x64	I-Operating_System
Edition	I-Operating_System
,	O
released	O
on	O
April	O
25	O
,	O
2005	O
,	O
is	O
an	O
edition	O
of	O
Windows	B-Application
XP	I-Application
for	O
x86-64	B-Device
personal	O
computers	O
.	O
</s>
<s>
It	O
is	O
designed	O
to	O
use	O
the	O
expanded	O
64-bit	B-Device
memory	O
address	O
space	O
provided	O
by	O
the	O
x86-64	B-Device
architecture	O
.	O
</s>
<s>
The	O
primary	O
benefit	O
of	O
moving	O
to	O
64-bit	B-Device
is	O
the	O
increase	O
in	O
the	O
maximum	O
allocatable	O
random-access	B-Architecture
memory	I-Architecture
(	O
RAM	B-Architecture
)	O
.	O
</s>
<s>
32-bit	O
editions	O
of	O
Windows	B-Application
XP	I-Application
are	O
limited	O
to	O
a	O
total	O
of	O
4	O
gigabytes	O
.	O
</s>
<s>
Although	O
the	O
theoretical	O
memory	O
limit	O
of	O
a	O
64-bit	B-Device
computer	I-Device
is	O
about	O
16	O
exabytes	O
(	O
17.1	O
billion	O
gigabytes	O
)	O
,	O
Windows	B-Operating_System
XP	I-Operating_System
x64	I-Operating_System
is	O
limited	O
to	O
128GB	O
of	O
physical	O
memory	O
and	O
16	O
terabytes	O
of	O
virtual	B-Architecture
memory	I-Architecture
.	O
</s>
<s>
Windows	B-Operating_System
XP	I-Operating_System
Professional	I-Operating_System
x64	I-Operating_System
Edition	I-Operating_System
uses	O
the	O
same	O
kernel	O
and	O
code	O
tree	O
as	O
Windows	B-Application
Server	I-Application
2003	I-Application
and	O
is	O
serviced	O
by	O
the	O
same	O
service	O
packs	O
.	O
</s>
<s>
However	O
,	O
it	O
includes	O
client	O
features	O
of	O
Windows	B-Application
XP	I-Application
such	O
as	O
System	O
Restore	O
,	O
Windows	B-Application
Messenger	I-Application
,	O
Fast	O
User	O
Switching	O
,	O
Welcome	O
Screen	O
,	O
Security	O
Center	O
and	O
games	O
,	O
which	O
Windows	B-Application
Server	I-Application
2003	I-Application
does	O
not	O
have	O
.	O
</s>
<s>
Windows	B-Operating_System
XP	I-Operating_System
Professional	I-Operating_System
x64	I-Operating_System
Edition	I-Operating_System
is	O
not	O
to	O
be	O
confused	O
with	O
Windows	B-Application
XP	I-Application
64-Bit	B-Device
Edition	O
as	O
the	O
latter	O
was	O
designed	O
for	O
Itanium	B-General_Concept
architecture	O
.	O
</s>
<s>
During	O
the	O
initial	O
development	O
phases	O
,	O
Windows	B-Operating_System
XP	I-Operating_System
Professional	I-Operating_System
x64	I-Operating_System
Edition	I-Operating_System
was	O
named	O
Windows	B-Application
XP	I-Application
64-Bit	B-Device
Edition	O
for	O
64-Bit	B-Device
Extended	O
Systems	O
.	O
</s>
<s>
Supports	O
up	O
to	O
128GB	O
of	O
RAM	B-Architecture
.	O
</s>
<s>
cores	B-Architecture
or	O
threads	B-Operating_System
on	O
a	O
single	O
CPU	B-General_Concept
)	O
.	O
</s>
<s>
As	O
such	O
,	O
,	O
the	O
OS	O
supports	O
all	O
commercially	O
available	O
multicore	B-Architecture
CPUs	I-Architecture
,	O
including	O
Intel	B-Device
Core	I-Device
series	O
,	O
or	O
AMD	O
FX	O
series	O
.	O
</s>
<s>
Uses	O
the	O
Windows	B-Application
Server	I-Application
2003	I-Application
kernel	O
which	O
is	O
newer	O
than	O
32-bit	O
Windows	B-Application
XP	I-Application
and	O
has	O
improvements	O
to	O
enhance	O
scalability	O
.	O
</s>
<s>
Windows	B-Operating_System
XP	I-Operating_System
Professional	I-Operating_System
x64	I-Operating_System
Edition	I-Operating_System
also	O
introduces	O
Kernel	O
Patch	O
Protection	O
(	O
also	O
known	O
as	O
PatchGuard	O
)	O
which	O
can	O
help	O
improve	O
security	O
by	O
helping	O
to	O
eliminate	O
rootkits	O
.	O
</s>
<s>
Supports	O
GPT-partitioned	O
disks	O
for	O
data	O
volumes	B-Application
(	O
but	O
not	O
bootable	O
volumes	B-Application
)	O
after	O
SP1	O
,	O
which	O
allows	O
disks	O
greater	O
than	O
2TB	O
to	O
be	O
used	O
as	O
a	O
single	O
GPT	B-Application
partition	I-Application
for	O
storing	O
data	O
.	O
</s>
<s>
Allows	O
faster	O
encoding	O
of	O
audio	O
or	O
video	O
,	O
higher	O
performance	O
video	O
gaming	O
and	O
faster	O
3D	O
rendering	O
in	O
software	O
optimized	O
for	O
64-bit	B-Device
hardware	O
.	O
</s>
<s>
Ships	O
with	O
Internet	B-Application
Information	I-Application
Services	I-Application
(	O
IIS	O
)	O
version	O
6.0	O
.	O
</s>
<s>
All	O
other	O
32-bit	O
editions	O
of	O
Windows	B-Application
XP	I-Application
have	O
IIS	O
v5.1	O
.	O
</s>
<s>
Ships	O
with	O
Windows	B-Device
Media	I-Device
Player	I-Device
(	O
WMP	B-Device
)	O
version	O
10	O
.	O
</s>
<s>
Windows	B-Application
XP	I-Application
Professional	O
shipped	O
with	O
WMP	B-Device
8	O
(	O
with	O
WMP	B-Device
9	O
shipping	O
with	O
Service	O
Pack	O
2	O
and	O
later	O
)	O
,	O
although	O
WMP	B-Device
11	I-Device
is	O
available	O
for	O
Windows	B-Application
XP	I-Application
Service	I-Application
Pack	I-Application
2	I-Application
or	O
later	O
.	O
</s>
<s>
Benefits	O
from	O
IPsec	B-Protocol
features	O
and	O
improvements	O
made	O
in	O
Windows	B-Application
Server	I-Application
2003	I-Application
.	O
</s>
<s>
Benefits	O
from	O
Shadow	O
Copy	O
features	O
introduced	O
in	O
Windows	B-Application
Server	I-Application
2003	I-Application
.	O
</s>
<s>
Remote	B-Protocol
Desktop	I-Protocol
Services	I-Protocol
supports	O
Unicode	O
keyboard	O
input	O
,	O
client-side	O
time-zone	O
redirection	O
,	O
GDI+	O
rendering	O
primitives	O
for	O
improved	O
performance	O
,	O
FIPS	O
encryption	O
,	O
fallback	O
printer	O
driver	O
,	O
auto-reconnect	O
and	O
new	O
Group	O
Policy	O
settings	O
.	O
</s>
<s>
Files	O
and	O
Settings	O
Transfer	O
Wizard	O
supports	O
migrating	O
settings	O
from	O
both	O
32-bit	O
and	O
64-bit	B-Device
Windows	B-Application
XP	I-Application
PCs	O
.	O
</s>
<s>
Windows	B-Operating_System
XP	I-Operating_System
Professional	I-Operating_System
x64	I-Operating_System
Edition	I-Operating_System
uses	O
a	O
technology	O
named	O
Windows-on-Windows	O
64-bit	B-Device
(	O
WoW64	B-Application
)	O
,	O
which	O
permits	O
the	O
execution	O
of	O
32-bit	O
software	O
.	O
</s>
<s>
It	O
was	O
first	O
used	O
in	O
Windows	B-Application
XP	I-Application
64-bit	B-Device
Edition	O
(	O
for	O
Itanium	B-General_Concept
architecture	O
)	O
.	O
</s>
<s>
Later	O
,	O
it	O
was	O
adopted	O
for	O
x64	B-Device
editions	I-Device
of	O
Windows	B-Application
XP	I-Application
and	O
Windows	B-Application
Server	I-Application
2003	I-Application
.	O
</s>
<s>
Since	O
the	O
x86-64	B-Device
architecture	O
includes	O
hardware-level	O
support	O
for	O
32-bit	O
instructions	O
,	O
WoW64	B-Application
simply	O
switches	O
the	O
process	B-Operating_System
between	O
32	O
-	O
and	O
64-bit	B-Device
modes	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
x86-64	B-Device
architecture	O
microprocessors	O
suffer	O
no	O
performance	O
loss	O
when	O
executing	O
32-bit	O
Windows	O
applications	O
.	O
</s>
<s>
On	O
the	O
Itanium	B-General_Concept
architecture	O
,	O
WoW64	B-Application
was	O
required	O
to	O
translate	O
32-bit	O
x86	O
instructions	O
into	O
their	O
64-bit	B-Device
Itanium	B-General_Concept
equivalents	O
—	O
which	O
in	O
some	O
cases	O
were	O
implemented	O
in	O
quite	O
different	O
ways	O
—	O
so	O
that	O
the	O
processor	O
could	O
execute	O
them	O
.	O
</s>
<s>
All	O
32-bit	O
processes	O
are	O
shown	O
with	O
*	O
32	O
in	O
the	O
task	O
manager	O
,	O
while	O
64-bit	B-Device
processes	O
have	O
no	O
extra	O
text	O
present	O
.	O
</s>
<s>
Although	O
32-bit	O
applications	O
can	O
be	O
run	O
transparently	O
,	O
the	O
mixing	O
of	O
the	O
two	O
types	O
of	O
code	O
within	O
the	O
same	O
process	B-Operating_System
is	O
not	O
allowed	O
.	O
</s>
<s>
A	O
64-bit	B-Device
program	O
cannot	O
use	O
a	O
32-bit	O
dynamic-link	O
library	O
(	O
DLL	O
)	O
and	O
similarly	O
a	O
32-bit	O
program	O
cannot	O
use	O
a	O
64-bit	B-Device
DLL	O
.	O
</s>
<s>
This	O
may	O
lead	O
to	O
the	O
need	O
for	O
library	O
developers	O
to	O
provide	O
both	O
32-bit	O
and	O
64-bit	B-Device
binary	O
versions	O
of	O
their	O
libraries	O
.	O
</s>
<s>
Specifically	O
,	O
32-bit	O
shell	O
extensions	O
for	O
Windows	B-Protocol
Explorer	I-Protocol
fail	O
to	O
work	O
with	O
64-bit	B-Device
Windows	B-Protocol
Explorer	I-Protocol
.	O
</s>
<s>
Windows	B-Operating_System
XP	I-Operating_System
x64	I-Operating_System
Edition	I-Operating_System
ships	O
with	O
both	O
32-bit	O
and	O
64-bit	B-Device
versions	O
of	O
Windows	B-Protocol
Explorer	I-Protocol
.	O
</s>
<s>
Windows	B-Operating_System
XP	I-Operating_System
x64	I-Operating_System
Edition	I-Operating_System
also	O
includes	O
both	O
32-bit	O
and	O
64-bit	B-Device
versions	O
of	O
Internet	B-Application
Explorer	I-Application
6	I-Application
,	O
so	O
that	O
user	O
can	O
still	O
use	O
browser	B-Protocol
extensions	I-Protocol
or	O
ActiveX	B-Application
controls	I-Application
that	O
are	O
not	O
available	O
in	O
64-bit	B-Device
versions	O
.	O
</s>
<s>
Only	O
64-bit	B-Device
drivers	O
are	O
supported	O
in	O
Windows	B-Operating_System
XP	I-Operating_System
x64	I-Operating_System
Edition	I-Operating_System
,	O
but	O
32-bit	O
codecs	B-General_Concept
are	O
supported	O
as	O
long	O
as	O
the	O
media	B-Device
player	I-Device
that	O
uses	O
them	O
is	O
32-bit	O
.	O
</s>
<s>
By	O
default	O
,	O
64-bit	B-Device
(	O
x86-64	B-Device
)	O
Windows	O
programs	O
are	O
installed	O
onto	O
their	O
own	O
folders	O
under	O
folder	O
location	O
"	O
C:\Program	O
Files	O
"	O
,	O
while	O
32-bit	O
(	O
x86-32	O
)	O
Windows	O
programs	O
are	O
installed	O
onto	O
their	O
own	O
folders	O
under	O
folder	O
location	O
"	O
C:\Program	O
Files	O
(	O
x86	O
)	O
"	O
.	O
</s>
<s>
There	O
are	O
some	O
limitations	O
which	O
apply	O
to	O
Windows	B-Operating_System
XP	I-Operating_System
Professional	I-Operating_System
x64	I-Operating_System
Edition	I-Operating_System
:	O
</s>
<s>
NTVDM	O
and	O
Windows	B-Application
on	I-Application
Windows	I-Application
were	O
removed	O
,	O
so	O
16-bit	B-Device
Windows	O
applications	O
or	O
native	O
MS-DOS	B-Application
applications	O
cannot	O
run	O
.	O
</s>
<s>
Some	O
old	O
32-bit	O
programs	O
use	O
16-bit	B-Device
installers	O
which	O
do	O
not	O
run	O
;	O
however	O
,	O
replacements	O
for	O
16-bit	B-Device
installers	O
such	O
as	O
ACME	O
Setup	O
versions	O
2.6	O
,	O
3.0	O
,	O
3.01	O
,	O
3.1	O
and	O
InstallShield	B-Application
5.x	O
are	O
hardcoded	O
into	O
WoW64	B-Application
to	O
mitigate	O
this	O
issue	O
.	O
</s>
<s>
The	O
same	O
is	O
true	O
with	O
later	O
64-bit	B-Device
versions	O
of	O
Windows	O
.	O
</s>
<s>
Only	O
64-bit	B-Device
drivers	O
are	O
supported	O
.	O
</s>
<s>
Any	O
32-bit	O
Windows	B-Protocol
Explorer	I-Protocol
shell	O
extensions	O
fail	O
to	O
work	O
with	O
64-bit	B-Device
Windows	B-Protocol
Explorer	I-Protocol
.	O
</s>
<s>
However	O
,	O
Windows	B-Operating_System
XP	I-Operating_System
x64	I-Operating_System
Edition	I-Operating_System
also	O
ships	O
with	O
a	O
32-bit	O
Windows	B-Protocol
Explorer	I-Protocol
.	O
</s>
<s>
Previously	O
,	O
in	O
Windows	B-Application
XP	I-Application
Service	I-Application
Pack	I-Application
2	I-Application
,	O
running	O
the	O
executable	O
did	O
not	O
launch	O
it	O
,	O
but	O
it	O
stored	O
several	O
old	O
icons	O
.	O
</s>
<s>
Windows	B-Device
Command	I-Device
Prompt	I-Device
does	O
not	O
load	O
in	O
full-screen	O
.	O
</s>
<s>
Media	O
Bar	O
,	O
which	O
replaced	O
the	O
Radio	O
Toolbar	O
in	O
Internet	B-Application
Explorer	I-Application
6	I-Application
,	O
was	O
removed	O
.	O
</s>
<s>
Spell	O
checking	O
was	O
removed	O
from	O
Outlook	B-Application
Express	I-Application
.	O
</s>
<s>
IEEE	B-Protocol
1394	I-Protocol
(	O
FireWire	B-Protocol
)	O
audio	O
is	O
not	O
supported	O
.	O
</s>
<s>
Does	O
not	O
support	O
hibernation	O
if	O
PC	O
's	O
RAM	B-Architecture
is	O
greater	O
than	O
4GB	O
.	O
</s>
<s>
EFI	B-Architecture
or	O
UEFI	B-Architecture
are	O
not	O
supported	O
.	O
</s>
<s>
The	O
RTM	O
version	O
of	O
Windows	B-Operating_System
XP	I-Operating_System
Professional	I-Operating_System
x64	I-Operating_System
Edition	I-Operating_System
was	O
built	O
from	O
the	O
Windows	B-Application
Server	I-Application
2003	I-Application
Service	O
Pack	O
1	O
codebase	O
.	O
</s>
<s>
Because	O
Windows	B-Operating_System
XP	I-Operating_System
Professional	I-Operating_System
x64	I-Operating_System
Edition	I-Operating_System
comes	O
from	O
a	O
different	O
codebase	O
than	O
32-bit	O
Windows	B-Application
XP	I-Application
,	O
its	O
service	O
packs	O
are	O
also	O
developed	O
separately	O
.	O
</s>
<s>
For	O
the	O
same	O
reason	O
,	O
Service	O
Pack	O
2	O
for	O
Windows	B-Operating_System
XP	I-Operating_System
x64	I-Operating_System
Edition	I-Operating_System
,	O
released	O
on	O
March	O
13	O
,	O
2007	O
,	O
is	O
not	O
the	O
same	O
as	O
Service	O
Pack	O
2	O
for	O
32-bit	O
versions	O
of	O
Windows	B-Application
XP	I-Application
.	O
</s>
<s>
In	O
fact	O
,	O
due	O
to	O
the	O
earlier	O
release	O
date	O
of	O
the	O
32-bit	O
version	O
,	O
many	O
of	O
the	O
key	O
features	O
introduced	O
by	O
Service	O
Pack	O
2	O
for	O
32-bit	O
(	O
x86	O
)	O
editions	O
of	O
Windows	B-Application
XP	I-Application
were	O
already	O
present	O
in	O
the	O
RTM	O
version	O
of	O
its	O
x64	B-Device
counterpart	O
.	O
</s>
<s>
Service	O
Pack	O
2	O
is	O
the	O
last	O
released	O
service	O
pack	O
for	O
Windows	B-Operating_System
XP	I-Operating_System
Professional	I-Operating_System
x64	I-Operating_System
Edition	I-Operating_System
.	O
</s>
<s>
A	O
machine	O
running	O
Windows	B-Operating_System
XP	I-Operating_System
Professional	I-Operating_System
x64	I-Operating_System
Edition	I-Operating_System
cannot	O
be	O
directly	O
upgraded	O
to	O
Windows	O
Vista	O
,	O
because	O
the	O
64	B-Device
bit	I-Device
Vista	O
DVD	O
mistakenly	O
recognizes	O
XP	B-Operating_System
x64	I-Operating_System
as	O
a	O
32-bit	O
system	O
.	O
</s>
<s>
XP	B-Operating_System
x64	I-Operating_System
does	O
qualify	O
the	O
customer	O
to	O
use	O
an	O
upgrade	O
copy	O
of	O
Windows	O
Vista	O
or	O
Windows	O
7	O
,	O
but	O
it	O
must	O
be	O
installed	O
as	O
a	O
clean	O
install	O
.	O
</s>
<s>
The	O
last	O
version	O
of	O
Microsoft	B-Application
Office	I-Application
to	O
be	O
compatible	O
with	O
Windows	B-Operating_System
XP	I-Operating_System
Professional	I-Operating_System
x64	I-Operating_System
Edition	I-Operating_System
is	O
Office	B-Application
2007	I-Application
,	O
and	O
the	O
last	O
version	O
of	O
Internet	B-Application
Explorer	I-Application
compatible	O
with	O
the	O
operating	O
system	O
is	O
Internet	B-Application
Explorer	I-Application
8	I-Application
(	O
Service	O
Pack	O
2	O
is	O
required	O
)	O
.	O
</s>
