<s>
The	O
Netwide	B-Application
Assembler	I-Application
(	O
NASM	B-Application
)	O
is	O
an	O
assembler	B-Language
and	O
disassembler	O
for	O
the	O
Intel	B-Operating_System
x86	I-Operating_System
architecture	O
.	O
</s>
<s>
It	O
can	O
be	O
used	O
to	O
write	O
16-bit	B-Device
,	O
32-bit	O
(	O
IA-32	B-Device
)	O
and	O
64-bit	B-Device
(	O
x86-64	B-Device
)	O
programs	O
.	O
</s>
<s>
It	O
is	O
considered	O
one	O
of	O
the	O
most	O
popular	O
assemblers	B-Language
for	O
Linux	B-Application
.	O
</s>
<s>
It	O
is	O
open-source	B-Application
software	I-Application
released	O
under	O
the	O
terms	O
of	O
a	O
simplified	O
(	O
2-clause	O
)	O
BSD	B-Operating_System
license	I-Operating_System
.	O
</s>
<s>
NASM	B-Application
can	O
output	O
several	O
binary	O
formats	O
,	O
including	O
COFF	O
,	O
OMF	O
,	O
a.out	O
,	O
Executable	O
and	O
Linkable	O
Format	O
(	O
ELF	O
)	O
,	O
Mach-O	B-Operating_System
and	O
binary	O
file	O
(	O
.bin	O
,	O
binary	O
disk	O
image	O
,	O
used	O
to	O
compile	O
operating	B-General_Concept
systems	I-General_Concept
)	O
,	O
though	O
position-independent	B-Operating_System
code	I-Operating_System
is	O
supported	O
only	O
for	O
ELF	O
object	B-Application
files	I-Application
.	O
</s>
<s>
It	O
also	O
has	O
its	O
own	O
binary	O
format	O
called	O
RDOFF	B-Application
.	O
</s>
<s>
The	O
variety	O
of	O
output	O
formats	O
allows	O
retargeting	B-Application
programs	O
to	O
virtually	O
any	O
x86	B-Operating_System
operating	B-General_Concept
system	I-General_Concept
(	O
OS	O
)	O
.	O
</s>
<s>
It	O
can	O
also	O
create	O
flat	O
binary	O
files	O
,	O
usable	O
to	O
write	O
boot	B-Operating_System
loaders	I-Operating_System
,	O
read-only	B-Device
memory	I-Device
(	O
ROM	B-Device
)	O
images	O
,	O
and	O
in	O
various	O
facets	O
of	O
OS	O
development	O
.	O
</s>
<s>
It	O
can	O
run	O
on	O
non-x86	O
platforms	O
as	O
a	O
cross	O
assembler	B-Language
,	O
such	O
as	O
PowerPC	B-Architecture
and	O
SPARC	B-Architecture
,	O
though	O
it	O
cannot	O
generate	O
programs	O
usable	O
by	O
those	O
machines	O
.	O
</s>
<s>
NASM	B-Application
uses	O
a	O
variant	O
of	O
Intel	O
assembly	B-Language
syntax	O
instead	O
of	O
AT&T	O
syntax	O
.	O
</s>
<s>
It	O
also	O
avoids	O
features	O
such	O
as	O
automatic	O
generation	O
of	O
segment	B-Device
overrides	O
(	O
and	O
the	O
related	O
ASSUME	O
directive	O
)	O
used	O
by	O
MASM	B-Application
and	O
compatible	O
assemblers	B-Language
.	O
</s>
<s>
program	O
for	O
the	O
DOS	B-Device
operating	B-General_Concept
system	I-General_Concept
:	O
</s>
<s>
An	O
equivalent	O
program	O
for	O
Linux	B-Application
:	O
</s>
<s>
An	O
example	O
of	O
a	O
similar	O
program	O
for	O
Microsoft	B-Application
Windows	I-Application
:	O
</s>
<s>
A	O
64-bit	B-Device
program	O
for	O
Apple	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
that	O
inputs	O
a	O
keystroke	O
and	O
shows	O
it	O
on	O
the	O
screen	O
:	O
</s>
<s>
NASM	B-Application
principally	O
outputs	O
object	B-Application
files	I-Application
,	O
which	O
are	O
generally	O
not	O
executable	O
by	O
themselves	O
.	O
</s>
<s>
To	O
translate	O
the	O
object	B-Application
files	I-Application
into	O
executable	O
programs	O
,	O
an	O
appropriate	O
linker	B-Application
must	O
be	O
used	O
,	O
such	O
as	O
the	O
Visual	B-Application
Studio	I-Application
"	O
LINK	O
"	O
utility	O
for	O
Windows	B-Application
or	O
ld	B-Application
for	O
Unix-like	B-Operating_System
systems	I-Operating_System
.	O
</s>
<s>
NASM	B-Application
version	O
0.90	O
was	O
released	O
in	O
October	O
1996	O
.	O
</s>
<s>
Version	O
2.00	O
was	O
released	O
on	O
28	O
November	O
2007	O
,	O
adding	O
support	O
for	O
x86-64	B-Device
extensions	O
.	O
</s>
<s>
The	O
development	O
versions	O
are	O
not	O
uploaded	O
to	O
SourceForge.net,	O
but	O
are	O
checked	O
into	O
GitHub	B-Application
with	O
binary	O
snapshots	O
available	O
from	O
the	O
project	O
web	O
page	O
.	O
</s>
<s>
A	O
search	O
engine	O
for	O
NASM	B-Application
documentation	O
is	O
also	O
available	O
.	O
</s>
<s>
In	O
July	O
2009	O
,	O
as	O
of	O
version	O
2.07	O
,	O
NASM	B-Application
was	O
released	O
under	O
the	O
Simplified	O
(	O
2-clause	O
)	O
BSD	B-Operating_System
license	I-Operating_System
.	O
</s>
<s>
Previously	O
,	O
because	O
it	O
was	O
licensed	O
under	O
LGPL	B-Application
,	O
it	O
led	O
to	O
development	O
of	O
Yasm	O
,	O
a	O
complete	O
rewrite	O
of	O
under	O
the	O
New	O
BSD	B-Operating_System
License	I-Operating_System
.	O
</s>
<s>
Yasm	O
offered	O
support	O
for	O
x86-64	B-Device
earlier	O
than	O
NASM	B-Application
.	O
</s>
<s>
It	O
also	O
added	O
support	O
for	O
GNU	B-Application
Assembler	I-Application
syntax	O
.	O
</s>
<s>
Relocatable	B-Application
Dynamic	I-Application
Object	I-Application
File	I-Application
Format	I-Application
(	O
RDOFF	B-Application
)	O
is	O
used	O
by	O
developers	O
to	O
test	O
the	O
integrity	O
of	O
NASM	B-Application
's	O
object	B-Application
file	I-Application
output	O
abilities	O
.	O
</s>
<s>
It	O
is	O
based	O
heavily	O
on	O
the	O
internal	O
structure	O
of	O
NASM	B-Application
,	O
essentially	O
consisting	O
of	O
a	O
header	O
containing	O
a	O
serialization	B-Application
of	O
the	O
output	O
driver	O
function	O
calls	O
followed	O
by	O
an	O
array	O
of	O
sections	O
containing	O
executable	O
code	O
or	O
data	O
.	O
</s>
<s>
Tools	O
for	O
using	O
the	O
format	O
,	O
including	O
a	O
linker	B-Application
and	O
loader	O
,	O
are	O
included	O
in	O
the	O
NASM	B-Application
distribution	O
.	O
</s>
<s>
Until	O
version	O
0.90	O
was	O
released	O
in	O
October	O
1996	O
,	O
NASM	B-Application
supported	O
output	O
of	O
only	O
flat-format	O
executable	O
files	O
(	O
e.g.	O
,	O
DOS	B-Device
COM	O
files	O
)	O
.	O
</s>
<s>
In	O
version	O
0.90	O
,	O
Simon	O
Tatham	O
added	O
support	O
for	O
an	O
object-file	O
output	O
interface	O
,	O
and	O
for	O
DOS	B-Device
.OBJ	O
files	O
for	O
16-bit	B-Device
code	O
only	O
.	O
</s>
<s>
NASM	B-Application
thus	O
lacked	O
a	O
32-bit	O
object	B-Application
format	I-Application
.	O
</s>
<s>
To	O
address	O
this	O
lack	O
,	O
and	O
as	O
an	O
exercise	O
to	O
learn	O
the	O
object-file	O
interface	O
,	O
developer	O
Julian	O
Hall	O
put	O
together	O
the	O
first	O
version	O
of	O
RDOFF	B-Application
,	O
which	O
was	O
released	O
in	O
NASM	B-Application
version	O
0.91	O
.	O
</s>
<s>
Since	O
this	O
initial	O
version	O
,	O
there	O
has	O
been	O
one	O
major	O
update	O
to	O
the	O
RDOFF	B-Application
format	O
,	O
which	O
added	O
a	O
record-length	O
indicator	O
on	O
each	O
header	O
record	O
,	O
allowing	O
programs	O
to	O
skip	O
over	O
records	O
whose	O
format	O
they	O
do	O
not	O
recognise	O
,	O
and	O
support	O
for	O
multiple	O
segments	O
;	O
RDOFF1	O
only	O
supported	O
three	O
segments	O
:	O
text	O
,	O
data	O
and	O
bss	O
(	O
containing	O
uninitialized	O
data	O
)	O
.	O
</s>
<s>
The	O
RDOFF	B-Application
format	O
is	O
strongly	O
deprecated	O
and	O
has	O
been	O
disabled	O
starting	O
in	O
NASM	B-Application
2.15.04	O
.	O
</s>
