Every release includes SHA256SUMS.txt. Check a download with shasum -a 256 -c SHA256SUMS.txt.

Both macOS downloads require macOS 12.3 or later. Take the Apple Silicon build on an M-series Mac and the Intel build on an Intel one. The Intel build also runs on an M-series Mac under Rosetta 2; the Apple Silicon build cannot run on an Intel Mac.

Assembling for the Z80 machines

VASM is one executable per CPU. The downloads above are the 6502 build, which covers the Commodore, Atari, Apple II and NES families. The Spectrum, ZX81, Amstrad CPC, MSX, ColecoVision, Game Boy and the other Z80, 8080 and Game Boy targets need the Z80 build:

Download Z80 for macOS Windows Linux

Put it in the same folder as the 6502 build, under the name it arrives with (vasmz80_oldstyle_linux-x86_64, vasmz80_oldstyle_macos-universal or vasmz80_oldstyle_windows-x64.exe) or renamed to vasmz80_oldstyle (vasmz80_oldstyle.exe on Windows) — Crusty Studio resolves either. Point the VASM folder setting at that folder rather than at one of the files, and Crusty Studio picks the build each target names from what is in it.

Assembling for the Color Computer

The TRS-80 Color Computer is a 6809 machine, so it needs a third build. There is no Windows download for this one: the author publishes no Win64 archive for the 6809 build, and this site only redistributes the Windows archives he publishes.

Download 6809 for macOS Linux

It goes in the same folder as the other two, under the name it arrives with (vasm6809_oldstyle_linux-x86_64 or vasm6809_oldstyle_macos-universal) or renamed to vasm6809_oldstyle. On Windows, build it from the source archive with make CPU=6809 SYNTAX=oldstyle under MSYS2 or Cygwin. A Color Computer build that cannot find it stops and names the missing assembler, and the Color Computer is the only 6809 target, so nothing else needs it. A Color Computer build is a .ccc cartridge, which both MAME and XRoar start on their own.

Then, on any platform

1. Put them together in one folder. A folder of your own is fine; so is tools/assemblers/vasm/<platform>/ inside the crustyBASIC folder, whose folder names are windows-x86_64, linux-x86_64, macos-aarch64 and macos-x86_64 — the macOS download serves both of those last two. Nothing has to be renamed: the suffixes the downloads carry are the platform each file was built for, and Crusty Studio reads them.
2. In Crusty Studio, choose Tools → Settings → Toolchain, set VASM folder to the folder holding the CPU builds, then Check installation. The check lists the builds it found and names the ones the folder is missing, so a folder holding only the 6502 build says so before you try to build for the Spectrum.

To confirm the version yourself, run it with no arguments — the first line begins vasm 2., and the current release reads vasm 2.0f. An older assembler is refused, because crustyBASIC emits assembly that needs a recent one.

About these builds

VASM is copyright © 2002–2026 Volker Barthelmann. It is redistributed here with his permission: each binary is compiled from the unmodified official source, and the manual and the source archive are included alongside them. Nothing in the source is patched or configured; the macOS and Linux builds are simply make CPU=6502 SYNTAX=oldstyle and make CPU=z80 SYNTAX=oldstyle. The Windows binaries are the archives the author publishes, redistributed unmodified.

README.txt lists every file, the source archive's SHA-256, and the exact commands used. LICENSE is the author's own. The manual is also online as HTML, and the author's own pages carry the release binaries: sun.hasenbraten.de/vasm and compilers.de/vasm.html.

Getting NASM

VASM covers the 6502, 68k and Z80 families. crustyBASIC's x86 targets — dos16, h120, pcjr, tandy1000, linux64 and win64 — hand their assembly to NASM instead, so install it only if you build for one of those systems.

1. Install NASM 2.x: brew install nasm on macOS, sudo apt install nasm on Debian and Ubuntu, or the installer from nasm.us on Windows.
2. Put nasm (nasm.exe on Windows) in tools/assemblers/nasm/<platform>/ inside the crustyBASIC folder, or point the NASM assembler field in Tools → Settings → Toolchain straight at it.

nasm -v prints NASM version 2.16.01 compiled on …. The other targets build with VASM alone, so a missing NASM does not stop a C64, NES or Atari build.

1. Install the toolchain. Crusty Studio drives tools you install yourself: crustyBASIC, VASM vasm6502_oldstyle 2.x (download it above), NASM for the x86 targets, and an emulator for your machine — VICE for the Commodore machines, Mesen, FCEUX, ares or BizHawk for the NES.
2. Point the studio at them. Open Tools → Settings → Toolchain, choose the compiler and assemblers, and add the folder holding your emulators. Check installation confirms what it can find.
3. Open or create a project. Project → New creates a project folder with src/main.cbs, folders for each asset type, and a .crusty manifest. The demo projects from the download above are good starting points.
4. Write, build, run. Press Build and run and the studio saves the source, calls crustyBASIC with VASM, reports what the compiler said, and launches the artifact in the emulator.

@OPTION TARGET c64

PROC MAIN
    CLS
    POSITION 0, 0
    PRINT "HELLO, C64!"
ENDPROC

Crusty Studio is not open source. The applications published here are provided for use with crustyBASIC; the source code is not published and no rights to it are granted. crustyBASIC itself is a separate project under its own terms.

Reporting a problem works best with the version you downloaded, your operating system, the target you were building for, and the contents of the Output panel if a build was involved.