<s>
In	O
a	O
segmented	B-General_Concept
architecture	I-General_Concept
computer	O
,	O
a	O
far	B-General_Concept
pointer	I-General_Concept
is	O
a	O
pointer	O
which	O
includes	O
a	O
segment	B-Device
selector	I-Device
,	O
making	O
it	O
possible	O
to	O
point	O
to	O
addresses	O
outside	O
of	O
the	O
default	O
segment	O
.	O
</s>
<s>
Comparison	O
and	O
arithmetic	O
on	O
far	B-General_Concept
pointers	I-General_Concept
is	O
problematic	O
:	O
there	O
can	O
be	O
several	O
different	O
segment-offset	O
address	O
pairs	O
pointing	O
to	O
one	O
physical	B-General_Concept
address	I-General_Concept
.	O
</s>
<s>
For	O
example	O
,	O
in	O
an	O
Intel	B-General_Concept
8086	I-General_Concept
,	O
as	O
well	O
as	O
in	O
later	O
processors	O
running	O
16-bit	B-Device
code	O
,	O
a	O
far	B-General_Concept
pointer	I-General_Concept
has	O
two	O
parts	O
:	O
a	O
16-bit	B-Device
segment	B-Device
value	I-Device
,	O
and	O
a	O
16-bit	B-Device
offset	B-General_Concept
value	O
.	O
</s>
<s>
A	O
linear	O
address	O
is	O
obtained	O
by	O
shifting	O
the	O
binary	O
segment	B-Device
value	I-Device
four	O
times	O
to	O
the	O
left	O
,	O
and	O
then	O
adding	O
the	O
offset	B-General_Concept
value	O
.	O
</s>
<s>
Hence	O
the	O
effective	O
address	O
is	O
20bits	O
(	O
actually	O
21-bit	O
,	O
which	O
led	O
to	O
the	O
address	O
wraparound	O
and	O
the	O
Gate	B-Device
A20	I-Device
)	O
.	O
</s>
<s>
There	O
can	O
be	O
up	O
to	O
4096	O
different	O
segment-offset	O
address	O
pairs	O
pointing	O
to	O
one	O
physical	B-General_Concept
address	I-General_Concept
.	O
</s>
<s>
To	O
compare	O
two	O
far	B-General_Concept
pointers	I-General_Concept
,	O
they	O
must	O
first	O
be	O
converted	O
(	O
normalized	O
)	O
to	O
their	O
20-bit	O
linear	O
representation	O
.	O
</s>
<s>
On	O
C	B-Language
compilers	B-Language
targeting	O
the	O
8086	B-General_Concept
processor	O
family	O
,	O
far	B-General_Concept
pointers	I-General_Concept
were	O
declared	O
using	O
a	O
non-standard	O
far	O
qualifier	O
.	O
</s>
<s>
For	O
example	O
,	O
char	O
far	O
*	O
p	O
;	O
defined	O
a	O
far	B-General_Concept
pointer	I-General_Concept
to	O
a	O
char	O
.	O
</s>
<s>
The	O
difficulty	O
of	O
normalizing	O
far	B-General_Concept
pointers	I-General_Concept
could	O
be	O
avoided	O
with	O
the	O
non-standard	O
huge	O
qualifier	O
.	O
</s>
<s>
Example	O
of	O
far	B-General_Concept
pointer	I-General_Concept
:	O
</s>
<s>
Physical	B-General_Concept
Address	I-General_Concept
=	O
(	O
value	O
of	O
segment	B-General_Concept
register	I-General_Concept
)	O
*	O
0x10	O
+	O
(	O
value	O
of	O
offset	B-General_Concept
)	O
.	O
</s>
