VIOS Manual
VIOS Manual
**VIOS** is a small, malleable operating system for the Agon Light 2, built around a resident Forth. You type Forth at a console on the VGA screen or drive the same system from a Mac; you browse, edit and replace running code in Smalltalk-style windows; and you keep what you build as checked source modules on the SD card.
Live development: a word added to a module in the Browser, accepted, then used in the Workspace
**Source code, releases and issues:**github.com/alexiob/VIOS
This manual covers building VIOS from source, installing it, setting it up and using it: the console, the Forth language as VIOS implements it, modules, tasks, files and devices, the GUI and its tools, sound, and the host tools. It ends with example programs and a reference of every word.
_Edition: VIOS 0.8.0, October 2026, by Alessandro Iob (iob.dev). The version is in the `VERSION` file; what changed is in `CHANGELOG.md`. All screenshots are rendered on a host computer by the real VIOS display server and GUI code (see Images in this manual); the board draws the same pixels._
Contents
1. Introduction 2. Architecture 3. Hardware and Wiring 4. Building 5. Installing 6. First Boot and Setup 7. The Console and REPL 8. The Forth Language 9. Display and Graphics 10. Modules and Persistence 11. Tasks and Preemption 12. Handles, Pipes and Devices 13. Files and the SD Card 14. The GUI 15. The GUI Tools 16. Audio 17. The Host Harness and MCP Tools 18. Troubleshooting 19. Example Programs 20. Word Reference 21. Appendix: Limits and Numbers