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The Netwide Assembler, NASM, is an 80x86 assembler designed for
portability and modularity. It supports a range of object file formats,
including Linux and
, Microsoft 16-bit
. It will
also output plain binary files. Its syntax is designed to be simple and
easy to understand, similar to Intel's but less complex. It supports
and has macro capability.
The Netwide Assembler grew out of an idea on
- I forget which), which was
essentially that there didn't seem to be a good free x86-series
assembler around, and that maybe someone ought to write one.
is good, but not free, and in particular you don't get any 32-bit capability until you pay. It's DOS only, too.
is free, and ports over DOS and Unix, but it's not very good, since it's designed to be a back end to
, which always feeds it correct code. So its error checking is minimal. Also, its syntax is horrible, from the point of view of anyone trying to actually write anything in it. Plus you can't write 16-bit code in it (properly).
is Minix- and Linux-specific, and (my version at least) doesn't seem to have much (or any) documentation.
isn't very good, and it's (was) expensive, and it runs only under DOS.
is better, but still strives for MASM compatibility, which means millions of directives and tons of red tape. And its syntax is essentially MASM's, with the contradictions and quirks that entails (although it sorts out some of those by means of Ideal mode). It's expensive too. And it's DOS-only.
So here, for your coding pleasure, is NASM. At present it's still in prototype stage - we don't promise that it can outperform any of these assemblers. But please, please send us bug reports, fixes, helpful information, and anything else you can get your hands on (and thanks to the many people who've done this already! You all know who you are), and we'll improve it out of all recognition. Again.
Please see the file
, supplied as part
of any NASM distribution archive, for the licence conditions under which
you may use NASM. NASM is now under the so-called GNU Lesser General Public
The current version of NASM (since about 0.98.08) are maintained by a
team of developers, accessible through the
mailing list (see below for the link).
If you want to report a bug, please read
section 10.2 first.
NASM has a WWW page at
If it's not there, google for us!
The original authors are e-mailable as
The latter is no longer involved in the development team.
New releases of NASM are uploaded to the official sites
Announcements are posted to
If you want information about NASM beta releases, and the current
development status, please subscribe to the
email list by registering at
Once you've obtained the DOS archive for NASM,
denotes the version number of NASM contained in the archive), unpack it
into its own directory (for example
The archive will contain four executable files: the NASM executable
, and the NDISASM executable files
. In each case, the file whose name
executable, designed to run under
Intel, and the other one is a 16-bit
The only file NASM needs to run is its own executable, so copy (at
least) one of
to a directory on your PATH, or
to add the
directory to your
. (If you're only installing the
version, you may wish to rename it to
That's it - NASM is installed. You don't need the nasm directory to be
present to run NASM (unless you've added it to your
), so you can delete it if you need to save
space; however, you may want to keep the documentation or test programs.
If you've downloaded the DOS source archive,
directory will also contain the full NASM source code, and a selection of
Makefiles you can (hopefully) use to rebuild your copy of NASM from
Note that the source files
are automatically generated from the
master instruction table
by a Perl
script; the file
is generated from
by another Perl script. Although the
NASM source distribution includes these generated files, you will need to
rebuild them (and hence, will need a Perl interpreter) if you change
insns.dat, standard.mac or the documentation. It is possible future source
distributions may not include these files at all. Ports of Perl for a
variety of platforms, including DOS and Windows, are available from
Once you've obtained the Unix source archive for NASM,
denotes the version number of NASM contained
in the archive), unpack it into a directory such as
. The archive, when unpacked, will
create its own subdirectory
NASM is an auto-configuring package: once you've unpacked it,
to the directory it's been unpacked into and
. This shell script will find the
best C compiler to use for building NASM and set up Makefiles accordingly.
Once NASM has auto-configured, you can type
to build the
binaries, and then
to install them in
and install the man pages
. Alternatively, you can give
options such as
to the configure script
(see the file
for more details), or
install the programs yourself.
NASM also comes with a set of utilities for handling the
custom object-file format, which are in the
subdirectory of the NASM archive. You can
build these with
and install them with
, if you want them.
If NASM fails to auto-configure, you may still be able to make it
compile by using the fall-back Unix makefile
. Copy or rename that file to
and try typing
. There is also a Makefile.unx file in the
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