The Duo Ultimate H1 is a USB adapter that lets you plug real Atari joysticks and paddles into your PC. RetroArch can then use them to play Atari 2600 games. This guide covers the whole process from plugging in to saving your settings, and it’s written for beginners — no prior RetroArch experience needed.

1. Connect the adapter (order matters)

The Duo Ultimate is detected most reliably if you start it in this order:

1. Start RetroArch first, while the Duo Ultimate is still powered off.
2. Now power on the Duo Ultimate. RetroArch should detect it automatically. You’ll usually see a couple of small notifications float up from the bottom of the screen — typically “PS3 Controller 1” and “PS3 Controller 2.” Those are the adapter’s two ports (two players), and it’s a good sign.

Why “PS3 Controller”? Windows recognizes the Duo Ultimate as a PS3-style gamepad — that’s just its default emulation mode. It behaves like an ordinary game controller plugged into your PC.

2. Set up Player 1 (Port 1) in RetroArch

First we’ll tell RetroArch which physical controller is Player 1 and teach it which buttons do what.

Open the input binds

From the RetroArch main menu, go to the top-level Settings menu → Input → RetroPad Binds.

Inside RetroPad Binds you’ll see Port 1 Controls, Port 2 Controls, and so on. Each port is a player: Port 1 = Player 1, Port 2 = Player 2.

Point Port 1 at the adapter, and keep it analog

Open Port 1 Controls and check two settings near the top:

• Device Index should read PS3 Controller (1). It’s usually set automatically. If it isn’t, press Enter on Device Index and pick PS3 Controller (1) from the list.
• Analog to Digital Type should be None. This keeps your input as true analog — essential for paddles, which need smooth, continuous left-and-right motion rather than being chopped into digital left/right.

Map the buttons

Scroll down past Device Index to the list of buttons (D-Pad Up, B Button, and so on). Leave the D-Pad on its defaults. To set a button, select it and press Enter — RetroArch gives you about 2 seconds to press the button you want before it times out, so press and hold the button on the Duo until it registers.

Map these six:

Map the joystick directions

Keep scrolling to the Left Analog entries and move your joystick in each direction to bind it. These come out as axes:

3. Set up Player 2 (Port 2)

Set up Port 2 Controls the same way you did Port 1, with one difference:

• Device Index must be PS3 Controller (2) — the number (2), not (1).
• Analog to Digital Type = None, same as before.
• Map the buttons and joystick directions just like Port 1 — except you can skip Select and Start. On the Duo Ultimate, the Start and Select buttons live on Port 1 only, so they don’t matter for Port 2.

4. Turn on paddles in Stella 2014

The steps above cover joysticks. Paddles need one more layer of setup inside a game, using the Stella 2014 core.

1. Load an Atari 2600 game (for example, Breakout) using the Stella 2014 core, then press F1 to open the RetroArch Quick Menu.
2. Choose Controls.

Port 1 → Players 1 & 2

Open Port 1 Controls and set Device Type to Paddles (Stelladaptor). RetroArch relabels the controls to paddle functions. Confirm:

• B Button → P1 Fire
• A Button → P2 Fire

The paddle dials (the twist knobs) come from the Left Analog stick automatically: the X axis is Player 1’s paddle and the Y axis is Player 2’s paddle. So Port 1 alone gives you two paddle players.

Port 2 → Players 3 & 4

For four-player paddle games, open Port 2 Controls, set Device Type to Paddles (Stelladaptor), and confirm:

• B Button → P3 Fire
• A Button → P4 Fire

As with Port 1, the paddle dials come from the analog axes: X = Player 3, Y = Player 4.

5. Save your settings so you only do this once

To avoid redoing the paddle setup for every game, save it as a core remap. Still in the Controls menu, choose Manage Remap Files.

Then choose Save Core Remap File. This applies your paddle setup to every game you load with the Stella 2014 core. (If you’d rather limit it to one game or one folder, the Save Game Remap and Save Content Directory Remap options are right there too.)

6. Troubleshooting & tips

• Nothing detected when you power on the Duo? Make sure you started RetroArch first, then powered the adapter. Try toggling it off and on.
• Both players move together / Player 2 does nothing? Check that Port 1 = PS3 Controller (1) and Port 2 = PS3 Controller (2) — not both on (1).
• A and B feel reversed? The colors can differ between units. Map by button number: B = Button 0, A = Button 1.
• Paddles jump around or only one player works? Confirm you’re on the Stella 2014 core (not regular Stella), that Device Type = Paddles (Stelladaptor), and that Analog to Digital Type = None.
• Using paddles? Keep any mouse device on standby/off so it doesn’t interfere.

7. Quick reference tables

Port 1 button binds (Settings → Input → RetroPad Binds)

Paddle mapping (Stella 2014, Device Type = Paddles)

That’s it — your Atari joysticks and paddles should now play beautifully in RetroArch. Load up Breakout or Warlords and enjoy the classics the way they were meant to be played.