Projects / NASM - The Netwide Assembler

NASM - The Netwide Assembler

NASM is an 80x86 assembler designed for portability and modularity. It supports a range of object file formats including Linux a.out and ELF, COFF, Microsoft 16-bit OBJ, Win32/64, and Apple Mach-O. 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 all currently known opcodes, and has advanced macro capability. It includes a disassembler as well.

Operating Systems

Recent releases

  •  20 Jul 2009 05:43

    Release Notes: This is the first release under the 2-clause (simplified) BSD license. This release adds 64-bit Mach-O (Mac OS X) support and the ability to generate Intel hex or S-records directly, but is otherwise primarily a bugfix release.

    •  30 Jun 2009 01:25

      Release Notes: This release adds support for Intel AVX revision 5 and AMD XOP/FMA4/CVT16 revision 3.03. The preprocessor has a new indirect macro expansion feature, the ELF backends now supports thread-local storage, and a number of bugs have been fixed.

      •  29 Oct 2008 23:49

        Release Notes: This release fixes the parsing of the -W/-w (warning enable/disable) option, which was broken in 2.05. It is strictly a patch release.

        •  24 Oct 2008 04:31

          Release Notes: This release includes a massive overhaul of the ELF64 backend for spec compliance. It fixes incorrect offsets in RIP-relative addressing in immediate-carrying instructions, bugs in the ALIGN directive, the handling of the %include directive inside macros, and a handful of instructions that had incorrect patterns.

          •  26 Sep 2008 04:04

            Release Notes: This is primarily a bugfix release. In particular, it should end once and for all abnormalities introduced by forward references when pass-limited. It does introduce some new features, mostly in the preprocessor. It adds support for packed BCD and UTF-16/UTF-32 constants. It also adds support for "smart" alignment, padding the bypassed region with optimized code.

            Recent comments

            08 Jun 2002 18:59 hpa

            Re: Project in bit of limbo, or web site at least.
            The current web site is as given, (, or look at the project page on SourceForge, (

            07 Jan 2002 16:44 stompro

            Project in bit of limbo, or web site at least.
            There seems to be two web sites for this project,
            It seems that the address is the new one, but it seems to be hosted on someones cablemodem(From the speed). Note for people who need nasm for lame and gogo, The only version that worked for me was the 0.89bf version, to which there is only a zip file that you have do some work on. It stores all filenames as 8.3 and messes with the cases.
            If my info is wrong, someone please correct me.


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