Microsoft Macro Assembler
|Stable release||11.00.60315.1 / April 4, 2013|
|Operating system||Microsoft Windows and MS-DOS|
The Microsoft Macro Assembler (MASM) is an x86 assembler that uses the Intel syntax for MS-DOS and Microsoft Windows. Beginning with MASM 8.0 there are two versions of the assembler - one for 16-bit and 32-bit assembly sources, and another (ML64) for 64-bit sources only.
MASM is maintained by Microsoft, but since version 6.12 has not been sold as a separate product, it is instead supplied with various Microsoft SDKs and C compilers. Recent versions of MASM are included with Microsoft Visual Studio.
The earliest versions of MASM date back to 1981.
Version 6.0, released in 1992, added high-level programming support and a more C-like syntax. By the end of the year, version 6.1A updated the memory management to be compatible with code produced by Visual C++. In 1993 full support for 32-bit applications and the Pentium instruction set was added. The MASM binary at that time was shipped as a "bi-modal" DOS-extended binary (using the Phar Lap TNT DOS extender).
Versions 6.12 to 6.14 were implemented as patches for version 6.11. These patches changed the type of the binary to native PE format; version 6.11 is the last version of MASM that will run under MS-DOS.
In 1999 Intel released macros for SIMD and MMX instructions, which were shortly after supported natively by MASM. With the 6.15 release in 2000, Microsoft discontinued support for MASM as a separate product, instead subsuming it into the Visual Studio toolset. Though it was still compatible with Windows 98, current versions of Visual Studio were not. Support for 64-bit processors was not added until the release of Visual Studio 2005, with MASM 8.0.
Object module formats supported by MASM 
Since version 6.1, MASM is able to produce object modules in the Portable Executable (PE/COFF) format. PE/COFF is compatible with recent Microsoft C compilers, and object modules produced by either MASM or the C compiler can be routinely intermixed and linked into Win32 and Win64 binaries.
Some third-party tools that support MASM 
- IDAPro the Interactive Disassembler
Assemblers compatible with MASM 
Some other assemblers can assemble most code written for MASM, with the exception of more complex macros.
- Turbo Assembler (TASM) developed by Borland, later owned by Embarcadero, last updated in 2002 and supplied with Delphi and C++Builder for several years, later discontinued.
- JWASM Macro Assembler, licenced under the Sybase Open Watcom EULA.
- Pelle's Macro Assembler, a component of the Pelles C development environment.
See also 
- Watt, Peggy; Christine McGeever (January 7, 1985). "Macintosh Vs. IBM PC At One Year". InfoWorld 7 (1): pp. 15–16. ISSN 0199-6649. The IBM PC Macro Assembler was released in December 1981.
- Marshall, Martin (April 29, 1991). "Macro Assembler Update Adds High-Level Features". InfoWorld 13 (17): p. 21. ISSN 0199-6649.
- R. E. Harvey (2007). "Assemblers". Archived from the original on 16 February 2008. Retrieved 4 February 2010.
- Official Microsoft Macro Assembler Reference
- Intro to MASM Win32
- Win32 assembly tutorials using MASM
- Win32 Radasm