What TernOS Is
TernOS is a PalmOS-inspired operating system for modern e-ink microcontroller devices.
It targets hardware such as the XTEink X4 and M5Paper, provides a shared runtime and UI layer, and will be able to run native Rust applications as well a growing set of classic Palm applications.
This site focuses on the XTEink X4 workflow
Use it to flash the latest application firmware, convert EPUB books into Tern book files, and convert images into compact display formats that render well on-device.
To install Palm apps, copy the prc / pdb files to /install on the sdcard.
Current focus
TernOS is moving beyond single-purpose reader firmware toward a general system with hardware services, UI primitives, storage, databases, launcher apps, and a Palm compatibility layer. On desktop and X4, the reader and image-viewer path is already working well and some basic PalmOS apps, like Yoda, run.
What works today
- Launcher categories for apps, books, images, and recents.
- EPUB conversion into compact `.trbk` reader files with selectable fonts, image support and ToC.
- Image conversion into `.tri` and `.trimg` formats for e-ink screens.
- Application firmware flashing for the ESP32-C3 based XTEink X4.
- Some simple Palm apps like Yoda
Why this web app exists
The project needs a simple path for end users: flash firmware, prepare content, and manage files without installing separate desktop tools. The tabs here cover that path directly.
Device Files
Browse, delete, and add converted files directly on your TernOS device.
USB log
Flash Latest App Firmware
Uses WebSerial. Supported in Chrome and Edge.