Microsoft Macro Assembler
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The Microsoft Macro Assembler (abbreviated MASM) is an assembler for the x86 family of microprocessors. It was originally produced by Microsoft for development work on their MS-DOS operating system, and was for some time the most popular assembler available for that operating system. It supported a wide variety of macro facilities and structured programming idioms, including high-level constructions for looping, procedure calls and alternation (therefore, MASM is an example of a high-level assembler). Later versions added the capability of producing programs for the Windows operating systems that were released to follow on from MS-DOS. MASM is one of the few Microsoft development tools (another was NMAKE) for which there was no separate 16-bit and 32-bit versions.
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[edit] The competition
In the early 1990s, however, alternative assemblers such as Borland TASM, the shareware assembler A86, and (towards the end of the 90s) NASM began to take some of MASM's market share. However, two events in the late 1990's allowed MASM to retain much of its market share: first, Microsoft ceased selling MASM as a commercial product and began distributing it free of charge as part of the DDK (Driver Development Kit). Second, the MASM32 package and Iczelion's Win32 tutorials appeared, making Windows' application programming with MASM possible. Later in 2000, MASM 6.15 was released as part of the Visual C++ Processor Pack, which is free. As a result, all versions of Visual C++ later than 6.0, included a version of MASM equal to the version of Visual C++. Later in Visual C++ 2005, a 64-bit version of MASM appeared (file name is ml64.exe). Combined with the huge installed base of MASM users, these events helped stem the defection from MASM to other assemblers. Today, MASM is still the number one assembler on the Win32 platform, despite competition from new products such as NASM, FASM, GoAsm, and HLA.
[edit] Projects that support MASM
There are many on-going software development projects that support MASM, including IDEs (such as RadASM), debuggers (such as OllyDbg), and disassemblers (including IDAPro, the Interactive Disassembler). The MASM32 project (http://www.movsd.com/) has put together a very impressive programmer's library, sample code respository, and impressive documentation for MASM users. MASM is also supported by a large number of web pages and support forums (including http://www.masmforum.com). Despite the age of this product, it remains one of the most well-supported assemblers in existence.
[edit] MASM Versions
Though MASM is no longer a commercial product, Microsoft continues to support it because of the large base of assembly code that exists in-house at Microsoft. Since Microsoft stopped selling MASM separately, they have released several updates to the MASM v6.x product line (the last update is version 6.15, which was included in the Visual C++ 6.0 Processor Pack), they've released MASM v7.0, which was included with Visual C++ .NET 2002, MASM v7.1, which was included with Visual C++ .NET 2003 and MASM 8.0 (which came with Visual C++ 2005, and therefore including a version of MASM that can assemble x64 code). For the version included with newer Visual C++ versions, look for the file ml.exe in the Visual C++ bin directory, and for the version that can assemble x64 code included in Visual C++ 2005, look for the file ml64.exe in the same directory. Documentation for the versions included with newer Visual C++ versions is part of the documentation for that version.
[edit] Support
Though rumors exist that Microsoft no longer support and develop MASM, the truth is that Microsoft does continue to support and develop this product. Generally, though, the support is limited to adding new instructions as newer processors appear and improving 64-bit support; beyond this radical changes to the assembler will not be seen.
