# T-Modem-c1224 — HyBBX attach

**AS-IS** · prototype. Public term: **BBX** (not BBS). Never **AX25SRV** in public copy.

## Role

HyBBX does **not** run T-Modem L1. Attach to a running **max25d** that has device id **`tmodem`** enabled (USB KISS half-TNC from T-Modem-c1224 Pico firmware).

| Layer | Owns |
|-------|------|
| T-Modem-c1224 FW | HDLC + bitbang + chip AFSK + PTT |
| MAX25-Stack max25d | Device `tmodem` · `kiss-raw-serial` on `/dev/ttyACM*` |
| HyBBX | Network/BBX attach to max25d only |

Not BayCom/based. Not SER12.

## Example (default off)

```ini
[networks]
tmodem = no
```

When max25d already serves `tmodem`, prefer the existing **max25** / host attach path used for other MAX25 devices — enable only after max25d RX proof (RX before TX).

## Related

| Doc | Path |
|-----|------|
| MAX25 DEV | MAX25-Stack `docs/DEV/TMODEM-C1224.md` |
| BayCom/based (different) | [BAYCOM.md](BAYCOM.md) |
| TNCs | [TNCS.md](TNCS.md) |