# Comparison of assemblers

This is an incomplete comparison of assemblers. Some assemblers are components of a compiler system for a high-level programming language and may have limited or no usable functionality outside of the compiler system. Some assemblers are hosted on the target processor and operating system, while other assemblers (cross-assemblers) may run under an unrelated operating system or processor. For example, assemblers for embedded systems are not usually hosted on the target system since it would not have the storage and terminal I/O to permit entry of a program from a keyboard. An assembler may have a single target processor or may have options to support multiple processor types.

## As part of a compiler suite

* GNU Assembler (GAS): GPL: many target instruction sets, including ARM architecture, Atmel AVR, x86, x86-64, RISC-V, Freescale 68HC11, Freescale v4e, Motorola 680x0, MIPS, PowerPC, IBM System z, TI MSP430, Zilog Z80.
* SDAS (fork of ASxxxx Cross Assemblers and part of the Small Device C Compiler project): GPL: several target instruction sets including Intel 8051, Zilog Z80, Freescale 68HC08, PIC microcontroller.
* The Amsterdam Compiler Kit (ACK) targets many architectures of the 1980s, including 6502, 6800, 680x0, ARM, x86, Zilog Z80 and Z8000.
* LLVM targets many platforms, however its main focus is not machine-dependent code generation; instead a more high-level typed assembly-like intermediate representation is used. Nevertheless for the most common targets the LLVM MC (machine code) project provides an assembler both as an integrated component of the compilers and as an external tool.
* Some other self-hosted native-targeted language implementations (like Go, Free Pascal, SBCL) have their own assemblers with multiple targets. They may be used for inline assembly inside the language, or even included as a library, but aren't always suitable for being used outside of their framework - no command-line tool exists, or only the intermediate representation can be used as their input, or the set of supported targets is very limited.

## Single target assemblers
### 6502 assemblers

| Assembler | Developer | FOSS | License | Instruction set | Host platform |
| Atari Assembler Editor | Shepardson Microsystems | No | Proprietary | MOS Technology 6502 | Atari 8-bit |
| Atari Macro Assembler | Shepardson Microsystems | No | Proprietary | MOS Technology 6502 | Atari 8-bit |
| EDASM | Apple Computer | No | ? | MOS Technology 6502 | Apple DOS 3.x |
| k2asm | Andre Kaesmacher, Hauke Brandes, Börje Sieling | Yes | Artistic License | MOS Technology 6502 | Linux, Windows, macOS, possibly other Unices |
| Lisa | Randall Hyde | No | Proprietary | MOS Technology 6502 | Apple II |
| MAC/65 | Optimized Systems Software | No | Proprietary | MOS Technology 6502, WDC 65C02 | Atari 8-bit |
| Merlin | Glen Bredon | Yes | Public-domain | MOS Technology 6502, WDC 65C02 | Apple II |
| ORCA/M | The Byte Works | No | Proprietary, Free for non-commercial use | MOS Technology 6502, WDC 65C02, WDC 65C816 | ProDOS 8/16, GS/OS |
| RMAC | James Hammons, George Nakos, Landon Dyer | Yes | Free | MOS Technology 6502 | Linux, Windows, macOS |
| SynAssembler | Synapse Software | No | Proprietary | MOS Technology 6502 | Atari 8-bit |
| VASM | Volker Barthelmann, Frank Wille | No | Free | MOS Technology 6502 | various |
| xa65 | Cameron Kaiser, André Fachat | Yes | GPL | MOS Technology 6502, WDC 65C02, WDC 65C816 | Linux, various |
| XASM | Piotr Fusik | Yes | Free | MOS Technology 6502 | Linux, Windows, macOS |

### 680x0 assemblers

| Assembler | Developer | FOSS | License | Instruction set | Host platform | Development active |
| ASM-One Macro Assembler | Rune Gram-Madsen | No | Free | Motorola 680x0 | Commodore Amiga | No |
| GAS | GNU Project | Yes | Free | Motorola 680x0 | various | Yes |
| VASM | Volker Barthelmann, Frank Wille | No | Proprietary | Motorola 680x0 | various | Yes |
| RMAC | James Hammons, George Nakos, Landon Dyer | Yes | Free | Motorola 680x0, MOS Technology 6502 | Linux, Windows, macOS | Yes |

### ARM assemblers

| Assembler | Developer | FOSS | License | Host platform | ARM64 |
| GAS | GNU Project | Yes | GNU GPL | various | Yes |
| TCCASM | Fabrice Bellard | Yes | GNU LGPL | Unix-like, Windows | Yes |
| VASM | Volker Barthelmann, Frank Wille | No | Free | various | No |
| FASMARM | revolution, Tomasz Grysztar | Yes | Simplified BSD with weak copyleft | Windows, DOS, Linux, Unix-like | No |
| ARMIPS | Kingcom | Yes | MIT | various | No |

### RISC-V assemblers

| Assembler | Developer | FOSS | License | Host platform | RISC-V |
| GAS | GNU Project | Yes | GNU GPL | various | Yes |
| TCCASM | Fabrice Bellard | Yes | GNU LGPL | Unix-like, Windows | Yes |

### Mainframe Assemblers

| Assembler | Developer | FOSS | License | Instruction set | Host platform |
| Assembly Language for Multics (ALM) | | Yes | MIT | GE-645 Honeywell 6180 | GE-645 Honeywell 6180 |
| 705 Autocoder | IBM | | Free | IBM 705 | |
| 1410/7010 OS Autocoder | IBM | | Free | IBM 1410 7010 | IBM 1410 Processor Operating System (1410-PR-155) |
| 7070/7074 Autocoder | IBM | | Free | IBM 7070 IBM 7072 7074 | |
| 7080 Autocoder III | IBM | | Free | IBM 7080 | IBM 7058 Processor |
| COMPASS | Control Data Corporation | | Free | CDC lower 3000 series | CDC MASTER MSOS RTS OS SCOPE |
| COMPASS | Control Data Corporation | | Free | CDC upper 3000 series | CDC SCOPE |
| COMPASS | Control Data Corporation | | Free | CDC 6000 series 7600 Cyber 70, 170 | CDC Kronos NOS NOS/BE SCOPE |
| Fortran Assembly Program (FAP) | David E. Ferguson, Donald P. Moore | | Free | IBM 709, 704x, 709x | Fortran Monitor System, IBSYS |
| GCOS Macro Assembly Program (GMAP) | General Electric | | Free | GE-600 series, Honeywell 6000 series | GCOS |
| Macro Assembly Program (MAP) | IBM | | Free | IBM 709, 704x, 709x | IBSYS/IBJOB on 709, 704x, 709x |
| Symbolic Assembly Program (SAP) | United Aircraft | | Free | IBM 704 | IBM 704 |
| IBM Basic Assembly Language (BAL) | IBM | | Free | IBM System/360 | IBM BPS/360 |
| ASSIST | Penn State University | Public Domain | Free | IBM System/360 | MVS |
| UNIVAC VS/9 Assembler | Unisys | | Proprietary | Univac 9060 and 9070 (Similar to IBM System/370) | VS/9 |
| BS2000 Assembler H | Fujitsu | | Proprietary | Fujitsu Technology Series SE (Similar to IBM System/370) | BS2000 |
| z390 Portable Mainframe Assembler | Don Higgins | GPL | Free | Simulated IBM System/370 | Simulated MVS |
| IBM High-Level Assembler (HLASM) | IBM | — | Proprietary | IBM System/370. z/Architecture | z/OS, z/VSE, z/VM |
| IBM Assembler D | IBM | | Free | IBM System/360 | IBM OS/360 |
| IBM Assembler E | IBM | | Free | IBM System/360 | IBM OS/360 |
| IBM Assembler F | IBM | | Free | IBM System/360 | IBM OS/360 and CP-67/CMS |
| Assembler G | University of Waterloo | | Free | IBM System/360 and others (table-driven) | IBM OS/360 and CP-67/CMS |
| IBM Assembler H | IBM | — | Proprietary | IBM System/360 and System/370 | IBM OS/360 and successors |
| IBM Assembler XF | IBM | | Free | IBM System/370 | numerous |
| PL/360 | Niklaus Wirth | Yes | Free | IBM System/360 | IBM OS/360 |
| Meta-Symbol | Scientific Data Systems (SDS) | | Free | SDS Sigma series | BTM, UTS, CP-V |
| Xerox Assembly Program (AP) | Xerox Data Systems | | Free | SDS Sigma series, Xerox 500 series | CP-V CP-R |
| Meta Assembler (MASM) | UNIVAC | | Free | UNIVAC 1100/2200 series | UNIVAC EXEC 8 |

### POWER, PowerPC, and Power ISA assemblers

| Assembler | Developer | FOSS | License | Instruction set | Host platform |
| GAS | GNU Project | Yes | GNU GPL | POWER, PowerPC 74xx, PowerPC 970 | All platforms supported by GNU Binutils |
| IBM AIX assembler | IBM | No | Proprietary | POWER | IBM AIX |
| VASM | Volker Barthelmann, Frank Wille | No | Free | POWER, 40x, 440, 460, 6xx, 7xx, 7xxx, 860, Book-E, e300 and e500 | various |

### x86 assemblers

| Assembler | Developer | Host platform | FOSS | License | x86-64 | Development active |
| A86/A386 | Eric Isaacson | Windows, DOS | No | Proprietary | No | No |
| ACK | Andrew Tanenbaum, Ceriel Jacobs | Linux, MINIX, Unix-like | Yes | BSD since 2003 | No | 1985-? |
| IBM ALP | IBM | OS/2 | No | Proprietary | No | No |
| Intel ASM86 | Intel | DOS | No | Proprietary | No | No |
| AT&T | AT&T | Unix System V | No | Proprietary | No | 1985-? |
| Digital Research RASM-86 Relocating Assembler | Digital Research | CP/M-86, DOS, Intel's ISIS and iRMX | No | Proprietary | No | 1978-1992 |
| FASM | Tomasz Grysztar | Windows, DOS, Linux, Unix-like | Yes | Simplified BSD with weak copyleft | Yes | Yes |
| GAS | GNU Project | Unix-like, Windows, DOS, OS/2 | Yes | GNU GPLv3 | Yes | Since 1987 |
| HLA | Randall Hyde | Windows, Linux, FreeBSD, macOS | Yes | Public domain | No | No |
| Open Watcom Assembler (HJWASM a.k.a. UASM, JWASM, WASM) | Watcom | Linux, Windows, DOS, FreeBSD, OS/2 | approved by OSI, but not by FSF | Sybase Open Watcom Public | Yes | Yes |
| MASM | Microsoft | Windows, DOS, OS/2 | No | Microsoft EULA | Yes | Since 1981 |
| NASM | Simon Tatham, Julian Hall, Hans Peter Anvin, et al. | Linux, macOS, Windows, DOS, OS/2 | Yes | BSD | Yes | Yes |
| POASM | | Windows, Windows Mobile | No | Freeware | Yes | Yes |
| Tim Paterson's ASM | Tim Paterson | 86-DOS, DOS DEBUG | No | Proprietary | No | 1979-1983 |
| TASM | Borland | Windows, DOS | No | Proprietary | No | ? |
| TCCASM | Fabrice Bellard | Unix-like, Windows | Yes | GNU LGPL | Yes | No |
| VASM | Volker Barthelmann, Frank Wille | various | No | Free | Yes | Yes |
| 86-Assembler for DOS | Stephen Duffy | DOS | Yes | GPL2 | No | No |
| Xenix | Microsoft | Xenix 2.3 and 3.0 (before 1985) | No | Proprietary | No | 1982-1984 |
| YASM | Peter Johnson | Windows, DOS, Linux, Unix-like | Yes | BSD | Yes | No |
* ^ Part of the MINIX 3 source tree, but without obvious development activity.
* ^ Developed by Interactive Systems Corporation in 1986 when they ported UNIX System V to Intel iAPX286 and 80386 architectures. Archetypical of ATT syntax because it was used as a reference for GAS. Still used for The SCO Group's products, UnixWare and OpenServer.
* ^ Active, supported, but unadvertised.
* ^ Part of the C++Builder Tool Chain, but not sold as a stand-alone product, or marketed since the CodeGear spin-off; Borland was still selling it until then. Version 5.0, the last, is dated 1996.
* ^ Turbo Assembler was developed as Turbo Editasm by Uriah Barnett from Speedware Inc (Sacramento, CA) between 1984 and 1987, then later sold to, or marketed by, Borland as their Turbo Assembler.
* ^ Last stable version 1.3.0 was released in August 2014, and low maintenance since then: https://github.com/yasm/yasm

### Z80 assemblers

| Assembler | Developer | Host platform | FOSS | License | Development active |
| Microsoft MACRO-80 | Microsoft | CP/M, ISIS-II, TRSDOS, TEKDOS, MSX-DOS | No | Commercial | No |
| Zeus Assembler | Crystal Computing | ZX Spectrum | No | Commercial | No |
| z80asm | Peter Kollner, Paul Flo Williams, John Critchley, Bas Wijnen | Unix-like, Windows | Yes | GNU GPL | No |
| sjasmplus | Sjoerd Mastijn, Aprisobal, Peter Helcmanovský, ... | Unix-like, Windows | Yes | BSD | Yes |
| Rasm | Berge Edouard | Unix-like, Windows | Yes | MIT | Yes |

### Other single target assemblers

| Assembler | Developer | FOSS | License | Instruction set | Host platform |
| Autocoder | IBM | | Free | IBM 1401, 1440, 1460 | IBM 1401, 1440, 1460 |
| Autocoder | IBM | | Free | IBM 1410, 7010 | 1410/7010 Operating System (1410-PR-155) |
| Babbage | | No | Proprietary | GEC 4000 series | GEC 4000 series |
| City & Guilds Mnemonic Code | City and Guilds of London Institute | No | ? | City & Guilds Computer | ICL 1900, Elliot 900 |
| MACRO-10 | Digital Equipment Corporation | | Free | PDP-10 | PDP-10 |
| MACRO-11 | Digital Equipment Corporation | | Free | PDP-11 | PDP-11 |
| VAX MACRO | Digital Equipment Corporation | | Proprietary | VAX, Alpha | OpenVMS |
| VASM | Volker Barthelmann, Frank Wille | No | Free | Zilog Z80, Motorola 6800 family | various |
| GPASM | James Bowman, Craig Franklin, David Barnett | Yes | GNU GPL | PIC microcontroller | many |
| MIPS | | | Free | MIPS | MIPS |
| Rednex Game Boy Development System (RGBDS) | | Yes | MIT License | Game Boy, Game Boy Color | many |
| Symbolic Optimal Assembly Program (SOAP) | IBM | | Free | IBM 650 | IBM 650 |
| Technical Assembly System (TASS) | | | Free | IBM 650 | IBM 650 |
| Symbolic Programming System (SPS) | Gary Mokotoff | | Free | IBM 14xx | IBM 1401, 1440, 1460 |
| Symbolic Programming System (SPS) | | | Free | IBM 1620, 1710 | IBM 1620, 1710 |
| ASMB, ASBL, NSBL - Numeric op codes, used for 1900 Operating System Executive | | No | Proprietary | ICL 1900 | ICL 1900 |
| GINerator mnemonic opcodes, used for GEORGE (operating system) | | No | Proprietary | ICL 1900 | ICL 1900 |
| PLAN mnemonic opcodes, used for commercial 1900 programs | | No | Proprietary | ICL 1900 | ICL 1900 |
| Single Address Assembly Language (SAAL) | | | Free | UNIVAC 1005 | UNIVAC 1005 |
| Sleuth | | | Free | UNIVAC 1107 | EXEC, EXEC II, EXEC 8 |
| Meta Assembler (MASM) | | | Free | UNIVAC 1100/2200 series | UNIVAC EXEC 8 |
| UTMOST | | | ? | UNIVAC III | UNIVAC III |

## Retargetable/cross-assemblers

| Assembler | Developer | FOSS | License | Instruction set | Host platform |
| The Macroassembler AS | Alfred Arnold | | Free | 29xxx, AVR, 65816, ACE, F2MC-8L, F2MC-16L, HMCS400, 6301, 6309, H8/300(H), H8/500, SH7000 / SH7600 / SH7700, HuC6280, PPC403GA, 4004/4040, 8008, MCS-48, MCS-41, MCS-51, MCS-251, MCS-96/196/296, 8080/8085, [ | Win32, DOS/DPMI, DOS (no longer maintained), OS/2 (no longer maintained), Linux |
| ASxxxx Cross Assemblers | Alan R. Baldwin | Yes | GNU GPL | 1802, S2650, SC/MP, MPS430, 6100, 61860, 6500, 6800(6802/6808), 6801(6803/HD6303), 6804, 6805, 68HC(S)08, 6809, 68HC11, 68HC(S)12, 68HC16, 740, 78K/0, 78K/0S, 8008, 8008S, 8048(8041/8022/8021), 8051, 8085(8080), AT89LP, 8X300(8X305), DS8XCXXX, AVR, EZ80, F2MC8L/FX, F8/3870, Game Boy(sm83), H8/3xx, Cypress PSoC(M8C), PIC, Rabbit 2000/3000, ST6, ST7, ST8, Z8, Z80(HD64180), and Z280 series | Win32, DOS, Linux, Android |