Open Source MS-DOS Assemblers

ACME is a free cross assembler released under the GNU GPL. It can produce code for the following processors: 6502, 6510 (including illegal opcodes), 65c02 and 65816. ACME supports the standard assembler stuff like global/local/anonymous labels, offset assembly, conditional assembly and looping assembly. It can include other source files as well as binaries while assembling. Calculations can be done in integer or float mode. Oh, and it is fast.

JWasm is a Masm-compatible assembler. It supports 16-, 32- and 64-bit code, instructions up to AVX and various output formats. It's written in C.

BEYE (Binary EYE) is a free, portable, advanced file viewer with built-in editor for binary, hexadecimal and disassembler modes. It contains a highlight AVR/Java/i86-AMD64/ARM-XScale/PPC-64 and other disassembler, full preview of MZ,NE,PE,ELF and other.

JWasm is a free MASM-compatible assembler with these features: native support for output formats Intel OMF, MS Coff (32/64-bit), Elf (32/64-bit), Binary, Windows PE (32/64-bit) and DOS MZ. precompiled JWasm binaries are available for DOS, Windows and Linux. For OS/2 and FreeBSD, makefiles are supplied. Instructions up to AVX are supported. JWasm is written in C. The source is portable and has successfully been tested with Open Watcom, MS VC, GCC and more. As far as programming for MS Windows is concerned, JWasm can be used with both WinInc (32/64-bit) and Masm32 (32-bit). Since v2.01, it will also work with Sven B. Schreiber's ancient WALK32. C header files can be converted to include files for JWasm with h2incX. JWasm's source code is released under the Sybase Open Watcom Public License, which allows free commercial and non-commercial use. There's a bunch of source samples available - they are supplied with the precompiled binary packages.

Win32 hosted tools to cross compile to DJGPP v1 (go32) for MS-DOS. Now includes GCC 1.27 aka the first version available to support the i386 processor.

An x86 assembler project with the following goals: 1) source level compatibility with MASM and TASM 2) support for the OMF object file format 3) support for 16-bit segmented code