fasm: fasm (fast assembler for the x86 and x86-64 architectures) fasm: fasm: The flat assembler (abbreviated to fasm, intentionally stylized fasm: with lowercase letters) is a fast assembler running in a variety fasm: of operating systems, in continued development since 1999. It was fasm: designed primarily for the assembly of x86 instructions and it fasm: supports x86 and x86-64 instruction sets with extensions like MMX, fasm: 3DNow!, SSE up to SSE4, AVX, AVX2, XOP, and AVX-512. It can produce fasm: output in plain binary, MZ, PE, COFF or ELF format. fasm: fasm: