Packet Terminal

Live site: https://packet-term.m0lte.uk

A self-contained browser terminal that uses @packet-net/ax25 and xterm.js to drive a USB KISS modem from the browser. Late-80s phosphor-CRT aesthetic, TNC2 command set.

What makes this particular terminal interesting: the AX.25 state machine it walks comes from ax25sdl, which is itself generated from the SDL diagrams in the AX.25 v2.2 specification. Updates to the spec's state-machine flow through into running code with no code changes here.

Run it

Open index.html in Chromium or Edge. No build step. The page imports @packet-net/ax25 and xterm.js from esm.sh at load time.

Web Serial isn't supported in Firefox or Safari. The page itself still loads (so you can read the help and see the layout), but ATTACH MODEM shows a "no Web Serial" notice.

TNC2 commands

Command	Meaning
HELP, ?	List commands
MYCALL <call>	Set or show your callsign (e.g. MYCALL M0LTE-1)
CONNECT <call>, C	Open a link to a remote station
DISCONNECT, D, BYE	Drop the link
STATUS, ST	Show link state, mode, frame counters
ECHO ON|OFF	Local-echo toggle (default ON)
CLEAR, CLS	Wipe the screen
VERSION, V	Runtime stack identity
MON ON|OFF, M	Toggle monitor mode

While connected, every keystroke is buffered and sent when you press Enter. Ctrl-C returns to command mode without disconnecting; type D to drop the link cleanly.

Architecture

                    ┌─────────────────────────────────┐
                    │           index.html            │
                    │                                 │
   keystrokes ──►   │   xterm.js  ──►  command parser │
                    │                  │              │
                    │                  ▼              │
                    │            @packet-net/ax25     │
                    │                  │              │
   USB Serial ◄───  │       WebSerialKissTransport    │
                    │                                 │
                    └─────────────────────────────────┘

Ax25Stack is constructed with a WebSerialKissTransport wrapping the SerialPort returned by navigator.serial.requestPort(). The TNC2 command parser maps text input to stack.connect({ from, to }) and session.write(bytes) / session.disconnect() calls. Inbound bytes from session.onData(...) go straight to xterm.

Scope

Connected-mode only — no UI/UNPROTO send, no via digipeater paths, no mod-128. MON ON opts in to BPQ-style passive frame tracing. The underlying library's full scope (what's in, what's out) is documented in the @packet-net/ax25 README.

How the live site updates

Pushes to main that touch index.html trigger .github/workflows/publish.yml, which uploads the file to OARC object storage. The OARC platform serves it back as the static site at packet-term.m0lte.uk. Round-trip from merge to live: ~10 seconds.

Provenance

Extracted from m0lte/packet.net on 2026-05-17 (history preserved via git filter-repo) — the demo used to live at web/ax25/examples/packet-terminal/ four levels deep in that monorepo. Now standalone: no build step, no package.json, no node_modules, just index.html and a tiny publish workflow.

Sibling repos

Repo	What it is
m0lte/packet-term-web (here)	Browser TNC2 emulator
m0lte/packet-term-tui	C# Terminal.Gui TUI — same idea on the desktop
m0lte/ax25-ts	@packet-net/ax25 — the library this demo consumes
m0lte/ax25sdl	SDL transcriptions + codegen — transitively consumed via @packet-net/ax25 → ax25sdl
m0lte/packet.net	.NET libraries + node host (the C# side of the stack)

License

MIT. Proudly built with AI assistance.