MASM

MASM, the Microsoft Macro Assembler, is an assembler for x86 architecture developed by Microsoft. It translates assembly language source files into object modules that can be linked with high-level languages such as C or C++. MASM has been shipped with Microsoft development tools since the early 1990s and was included with many versions of Visual Studio and the Windows Software Development Kit. It supports both 16-bit and 32-bit x86 code and uses a syntax compatible with the Intel style, augmented by Microsoft-specific macro facilities.

Key features include a macro language, support for defining data and code segments, labels, constants, and a rich set of directives for conditional assembly and procedural code. It also provides facilities for debugging information, includes, and symbol visibility. MASM can emit object formats compatible with Windows linkers, typically COFF, and can generate import libraries for use with DLLs and executables.

MASM is commonly used for writing low-level system routines, performance-critical components, and legacy code within Windows development. While newer or cross-platform assemblers exist, MASM remains a relevant tool for maintaining older projects and for learning x86 assembly within a Microsoft-centric toolchain. It is often invoked via command line or integrated into Visual Studio build configurations.