MOS for Visual Studio Code

Modern language, build, test, and debugging support for the MOS assembler.

Opening an .asm file activates the extension. In a trusted workspace, it downloads the latest MOS release for the current platform into VS Code's extension storage and starts mos lsp. On later starts it checks GitHub for a newer release and asks before updating. Set mos.executablePath to use a custom build instead.

Version 0.0.20 replaces the original datatrash.mos implementation while preserving its Marketplace identity, so existing installations upgrade in place. The legacy mos.path setting remains supported; new configurations should use mos.executablePath.

Features

• Syntax highlighting, diagnostics, completion, hover information, formatting, symbols, references, and rename through the MOS language server
• Build and test tasks using process execution and the MOS problem matcher
• Debug Adapter Protocol integration for VICE and MOS unit tests
• Automatic, cancellable updates with atomic installation and SHA-256 verification when GitHub supplies a digest
• Local, Remote SSH, Dev Container, WSL, and Codespaces support
• Multi-root support with an isolated language/debug server pair for each workspace folder
• Inline Run MOS and Debug MOS actions at basic_start target labels and * = ... program-counter assignments in the build entry file
• Restricted Mode support: highlighting remains available, but binaries are not downloaded or executed

Managed downloads are available for x64 Windows and for x64 or ARM64 Linux and macOS. Other platforms can use mos.executablePath.

Commands

• MOS: Build
• MOS: Run All Tests
• MOS: Install or Update Toolchain
• MOS: Restart Language Server

The inline application actions use the launch configuration named Launch with MOS by default. Change mos.launchConfiguration when your .vscode/launch.json uses a different name. If the configuration is missing, the extension offers to create it and prompts you to select your VICE executable.

Debugging

Create a launch.json configuration:

{
  "version": "0.2.0",
  "configurations": [
    {
      "type": "mos",
      "request": "launch",
      "name": "Launch with MOS",
      "workspace": "${workspaceFolder}",
      "preLaunchTask": "mos: Build",
      "vicePath": "/path/to/x64sc"
    }
  ]
}

VICE 3.5 or newer is required for its binary monitor support.

Development

Use Node.js 22 or newer.

npm install
npm run check
npm run package

The packaged VSIX is written to the repository's target directory.