SidecarTridge Multi-device for Atari ST

An apps platform for your Atari, in a cartridge

The SidecarTridge Multi-device plugs into the cartridge port of any Atari ST, STE, Mega, TT or Falcon. A Raspberry Pi Pico W inside brings Wi-Fi and a microSD slot, and runs a growing catalog of 12 modular apps. Boot floppy images. Swap ROMs over the air. Run a hard disk without opening the case. Download games online. No soldering, no internal mods.

A multi-device emulator for the Atari ST, STE, and Mega series on Raspberry Pi Pico steroids

SidecarTridge Multi-device (aka The SidecarT) is a state-of-the-art multi-device emulator crafted for the Atari ST, STE, and Mega series. It leverages the robust capabilities of the RP2040 microcontroller found in the Raspberry Pi Pico, enabling it to:

• Emulate both 64Kbyte and 128Kbyte ROMs by simply loading the binary files from a microSD card or via a Wi-Fi connection.

• Interact with the cartridge bus in real-time for data reading and writing, which allows for seamless emulation of devices such as floppy disks, hard disks, real-time clocks, keyboards, mouse devices, and more.

• Dive into a realm of possibilities, limited only by your creativity. Thanks to its open architecture and the open-source code, SidecarTridge can evolve to meet any challenge you envision.

Features

How It Works

Getting started takes about ten minutes. Six steps:

1. Install the hardware. Power off the Atari ST, STE, Mega, TT or Falcon. Slide the Multi-device into the lateral cartridge port. Power back on.

2. Connect the device to your Wi-Fi. On first boot the Multi-device exposes its own SIDECART Wi-Fi network. Join it from a phone or laptop, open http://192.168.4.1, pick your home Wi-Fi and save. From then on the device joins your network automatically. Full walkthrough in the quickstart guide.

3. Open the on-device app menu. Once connected, the Multi-device shows a QR code with the IP your router assigned. Scan it (or open the URL on a phone or laptop) to reach the web UI that lists every installed app.

4. Pick what your ST should become. Drives Emulator for floppy and hard-disk images from microSD. ROM Emulator for cartridge ROMs over Wi-Fi. Browser to search and boot floppy images online. MIDI-to-IP to bridge the MIDI port to the open Internet. RTC, and many more. See the Apps Catalog above for the full list.

5. Run your Atari. Reset or power-cycle the computer. The Multi-device behaves like the device the chosen app emulates, and stays in that mode across reboots until you switch apps.

6. Switch apps any time. Go back to the web UI, pick a different app, reboot the Atari. New apps land over the air as they ship.

Still on Firmware V1? The original flow boots from a SIDECART.TOS program on GEMDOS instead of the on-device app menu. We recommend updating to V2 to get the full apps catalog.

Video Gallery

What’s new in Version 3?

• Smaller & More Compact – A slimmer design makes installation easier while maintaining all functionality.
• Enhanced Performance & Stability – ENIG PCBs and optimized track layout improve signal integrity and reduce electrical noise, especially in older machines.
• Improved Power Efficiency – Optimized power handling lowers power consumption without compromising performance.
• Stronger WiFi Signal – A larger copper window for the WiFi antenna enhances signal strength and reduces interference.
• Flexible Pico W Integration – Supports direct soldering or reflowing of the Raspberry Pi Pico W for a professional-grade assembly.
• Expanded Connectivity for Makers – Now includes both JST and classic two-pin connectors to externalize the RESET and SELECT buttons, support UART for developers, and even enable DEBUG access for advanced users.

And of course, 100% backward compatible with the previous version.

Frequently Asked Questions

Should I use a Raspberry Pi Pico WH or W?

The device is compatible with both the Raspberry Pi Pico WH and W. The Raspberry Pi Pico WH (Reference SC0919) comes with the necessary 40-pin connectors to attach to the SidecarTridge’s motherboard. If you opt for the Raspberry Pi Pico W (Reference SC0918), you’ll need to procure two 20-pin connectors and solder them to the board yourself that you can find the store, or you can directly solder the Pico W to the board.

Can I use a Raspberry Pi Pico?

No, it is not compatible with the Raspberry Pi Pico. It requires the Infineon CYW43439 Wifi/Bluetooth module, which is only available in the Raspberry Pi Pico WH and W.

Can I use the Raspberry Pi Pico 2W?

No, at this time, the device is not compatible with the Raspberry Pi Pico 2W. But future versions of the firmware may support it.

Can I solder the Raspberry Pi Pico W to the board?

Yes. Starting with version 3, the board supports direct soldering of the Raspberry Pi Pico W for a more secure and integrated assembly.

What’s different between hardware revisions 2 and 3?

Revision 3 is a complete electronic redesign, making it smaller, more efficient, and fully compatible with the previous version. Key improvements include:

• More compact size for easier integration into enclosures.
• Lower power consumption for better efficiency.
• Stronger WiFi signal thanks to an improved antenna design.
• Expanded connectivity, including additional interface options for makers and developers.

While maintaining full backward compatibility, revision 3 delivers better performance and greater flexibility for users and case designers alike

What is the difference between the Multi-device and the TOS emulator?

They are different beasts. The Multi-device connects to the expansion port and can emulate different devices like external ROM (but not the TOS ROM), floppy, RTC, hard disk, etc. It works as an expansion device, not a replacement for an existing computer part. The TOS emulator replaces the internal ROM TOS with a custom board, making it as easy to change TOS versions as it is to change files in RAM. You can learn more about the TOS emulator in the TOS Emulator page.

Can the device harm my computer?

It has undergone extensive testing on various Atari ST, STE, MegaST, and MegaSTE computers featuring diverse TOS versions. However, it’s important to note that only the new Firmware version 2.0 supports Atari TT and Falcon, and their clones. While heavily modified and customized computers are likely compatible, it’s up to you to decide to use the device. As a rule of thumb, it’s guaranteed to work with any computer at stock speed.

What is new in Firmware v2?

Firmware V2 reworks the device into an apps platform (see the Apps Catalog above). Headline changes:

• Modular apps you can swap in seconds without reflashing.
• Over-the-air (OTA) updates and per-app configurations.
• Atari TT and Falcon support added.

Full architecture write-up in the docs. Latest builds on the downloads page.

It’s confusing. I don’t understand the difference between the hardware revisions and firmware versions.

The hardware revision refers to the physical design of the SidecarTridge Multi-device board. It has gone through different versions (revision 1, revision 2, and now revision 3), each with improvements in size, power efficiency, connectivity, and overall performance. You can learn about the differences between hardware revisions in the Documentation site.

The firmware version refers to the software that runs on the Raspberry Pi Pico W inside the SidecarTridge Multi-device. The firmware has also evolved over time, with version 1 being the initial release and version 2 introducing a new architecture with modular microfirmwares, OTA updates, and support for more devices like the Atari TT and Falcon.

Both firmware versions are compatible with all hardware revisions.

I don’t have good Wi-Fi near my computer. What can I do?

The microSD path stays fully usable without Wi-Fi. You can boot floppy and hard disk images straight from the card, and load ROMs that you have copied onto it. What needs a solid signal is the online layer (online floppy catalog, OTA updates, online ROM swapping). If your ST lives in a dead zone, the easiest fix is to move the router closer or to drop in a Wi-Fi repeater near the computer.

I want a case for my device. Where can I find one?

My lack of 3D printing skills is legendary, so I let the community do the work for me. You can find a list of cases in the cases page. The list grows very often, so if you have a case that you want to share with the community, please let me know!

I want to develop my own microfirmware for the device. What is the right Pico to use?

The Raspberry Pi Pico WH is the right choice. It bundles a JST SH 3x1mm male connector on top of the board, which connects to the Raspberry Pi Debug board. Also don’t forget to get a two JST SH 3x1mm female cable for the UART connection. You can learn more in this guide.

Can I contribute to the project?

Of course! Please visit the Documentation site page to learn how to start contributing to the project! No matter if you are a microcontroller ninja, an Atari ST guru, or a C aficionado. You are welcome!

Why are you open-sourcing the code?

Adopting the General Purpose License for the source code is my way of ensuring that the benefits belong to the community at large, rather than being held by a particular individual or entity.

Why are you open-sourcing the design with restrictions?

The essence of this project lies in community involvement and sheer passion, not profit-making. It’s disheartening to envision entities or individuals merely reproducing the design for commercial gains without adding any substantial value. While I’m completely supportive of enthusiasts creating their own device for personal use or for fellow aficionados, those aiming for monetary benefits should recognize the efforts and intentions behind this initiative. If profits are to be made, they should rightfully support the original creator or face the consequences of violating the license agreement.

Are device-compatible devices for sale in other online stores official?

No, they are not. If someone is trying to sell you a compatible device, it is not endorsed by the project or me. These devices are pirated designs and violate the license agreement. You can report any such instances to legal@sidecartridge.com for further action. Remember, any brand-new clone sold for profit is not an official product.

Where can I find ROM images?

I have gathered some images in this directory. You can download them, or simply connect the device to your Wi-Fi and browse the catalog online from your Atari ST!

Where can I find floppy images?

Just like in Soviet Russia, you don’t look for applications — they hunt you down. Use the embedded Browser microfirmware search engine to type a name, press Enter, and watch the Multi-device fetch and boot the floppy image for you.

Is this product for me?

Yes, if you enjoy tinkering with retro hardware. The Multi-device is built for hobbyists who like to experiment with their Atari ST. The polish is hobbyist polish, not consumer-electronics polish. In exchange you get capabilities and openness that no off-the-shelf product offers for the platform.

Wi-Fi is evil and I wear a tinfoil hat when it’s on. Is this device for me?

Probably not. The Multi-device is meant to be joyful and stress-free, and it spends a lot of time online. Make peace with radio waves first, then come back and we’ll still be here.

Why can’t I access the store even though you ship to my country?

Access to our products and community spaces requires basic respect. We have zero tolerance for harassment, personal attacks, abusive behavior, or defamatory content toward our team or community. We operate under a simple principle: don’t be abusive. If that principle is violated, access will be revoked. We build for people who enjoy experimenting, not creating hostility.

Certifications & Compliance

This product has been assessed for European (CE) and UK (UKCA) conformity. Click a variant to see its Declaration of Conformity and EMC Assessment reports.

Related products

Often paired with the Multi-device:

Internal TOS replacement

SidecarTridge TOS Emulator

Programmable TOS ROM emulator. Swap TOS versions as easily as files in RAM, no socket gymnastics.

Internal PSU

Internal USB-C PD PSU

Modern multi-rail USB-C PD power supply that drops into the original PSU bay of any ST, STE or MegaST.

External PSU brick

External USB-C PD PSU

External brick for the 520ST and any Atari without an internal PSU. USB-C in, multi-rail out.