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Getting Started: Atari 8-bit

FujiNet was originally designed for the Atari 8-bit line and has the most mature software ecosystem of any supported platform. This guide covers connecting the device and getting your first disk loaded.

Compatible computers

Computer Notes
Atari 400 SIO port on left side
Atari 800 SIO port on left side
Atari 600XL SIO port on right side
Atari 800XL SIO port on right side
Atari 65XE / 130XE SIO port on right side
Atari XEGS SIO port on right side

What you need

  • [x] FujiNet for Atari (SIO connector variant)
  • [x] SIO cable (usually included with the device)
  • [x] Your Atari computer
  • [x] Wi-Fi password for your 2.4 GHz network
  • [x] microSD card (FAT32, optional for local images)

Connection diagram

flowchart LR
    ATR[Atari 8-bit\nSIO Port] -->|SIO Cable| FN[FujiNet\nDevice]
    FN -->|Wi-Fi| NET[Internet / TNFS\nServers]
    FN -.->|SD Card| SD[(Local Disk\nImages)]

SIO is daisy-chainable

The SIO bus supports up to 8 devices chained together. FujiNet has two SIO connectors: plug the cable from your Atari into one end and chain additional SIO devices (like a real 1050 drive) from the other. FujiNet always acts as device 1 (D1:) by default.

Step 1: Connect the hardware

  1. Power off your Atari.
  2. Plug the SIO cable into the SIO port on your Atari.
  3. Plug the other end into either SIO port on the FujiNet.
  4. If you have a microSD card with disk images, insert it now.
  5. Do not power on yet.

Always connect SIO with power off

Plugging or unplugging SIO devices while the Atari is powered on can damage both the computer and the device.

Step 2: First power-on and Wi-Fi setup

  1. Power on the FujiNet first (if it has a separate power source), then power on your Atari.
  2. Many Atari models power the SIO bus — FujiNet may power directly from SIO.
  3. Watch the FujiNet LEDs:
  4. Solid blue — booting
  5. Flashing blue — connecting to Wi-Fi
  6. Flashing orange — no Wi-Fi configured (first run)
  7. If this is a first-time setup (no Wi-Fi saved), FujiNet creates a temporary Wi-Fi access point called FujiNet-XXXXXX.

Configuring Wi-Fi via the setup hotspot

  1. On a phone, tablet, or laptop: connect to the FujiNet-XXXXXX Wi-Fi network.
  2. Open a browser and navigate to http://192.168.4.1
  3. Click "WiFi Settings" and enter your home Wi-Fi network name (SSID) and password.
  4. Click Save — FujiNet will reboot and connect.
sequenceDiagram
    participant Phone
    participant FujiNet
    participant HomeWiFi

    FujiNet->>Phone: Broadcasts "FujiNet-XXXXXX" hotspot
    Phone->>FujiNet: Connect to hotspot
    Phone->>FujiNet: Open 192.168.4.1 — enter Wi-Fi credentials
    FujiNet->>FujiNet: Save credentials and reboot
    FujiNet->>HomeWiFi: Connect to home network
    HomeWiFi-->>FujiNet: Connected ✓

Step 3: Load the CONFIG app

CONFIG is the FujiNet control panel. On Atari, you access it by:

  1. Hold Option while booting (or just let the Atari boot normally — FujiNet will present CONFIG as the default disk).
  2. The CONFIG screen appears: a menu-driven interface for managing disk images, Wi-Fi, and settings.

If CONFIG doesn't appear automatically, you can force-load it: - Hold the button on the FujiNet device for 2 seconds while the Atari is running. This forces FujiNet to present CONFIG on the next cold boot.

Full CONFIG guide

See Using CONFIG — Atari 8-bit for a complete walkthrough of every CONFIG screen.

Step 4: Mount your first disk image

From an online TNFS server

  1. In CONFIG, navigate to Hosts & Devices.
  2. The default TNFS host tnfs.fujinet.online (or irata.online) is pre-configured.
  3. Browse to a directory, select a .ATR file, and press Return to mount it on D1:.
  4. Press Escape to exit CONFIG.
  5. Cold boot your Atari (hold Reset) — the mounted image will load.

From SD card

  1. Insert your FAT32-formatted microSD card with .ATR files.
  2. In CONFIG, go to Hosts & Devices, select the SD card host.
  3. Browse and mount as above.

Troubleshooting

Symptom Likely cause Fix
Atari shows BASIC or RAM test, no CONFIG FujiNet not powering on Check SIO cable; try external USB power
CONFIG loads but shows "No hosts" Wi-Fi not connected Check Wi-Fi settings in CONFIG → Network
Disk mounts but Atari won't boot it Image format mismatch Ensure the image is single-density .ATR or matches your drive type
FujiNet LED stays solid orange No SD card and no Wi-Fi Insert SD card or configure Wi-Fi first

Next steps