Wikipedia
Vasm
vasm is a free assembler supporting various CPUs and many different output formats.
CPUs officially supported by vasm include M680x0 family, ColdFire family, 80x86 family, PowerPC, ARM family, Z80 family, C16x/ ST10, 6502 etc. Vasm supports Standard MIT ( GNU-as style), Motorola/ Freescale 68k (Devpac compatible) and Old 8-bit style syntax flavours. Output file formats include ELF, a.out, Amiga hunk format, Atari TOS executable format, EHF extended hunk format, Raw, binary output, Motorola S-record format, VOBJ proprietary versatile object format, Test and debugging output.