What's New in beta-v0.0.12 (Changelog)

  • Real Time Clock
  • .MSA floppy images


A cartridge emulator for the Atari ST, STE, and Mega series on Raspberry Pi Pico steroids.

SidecarT is a state-of-the-art cartridge ROM 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, SidecarT can evolve to meet any challenge you envision.


  1. Versatile ROM Emulation: Easily emulate 64Kbyte and 128Kbyte ROMs. With SidecarT, switching between ROMs is a breeze—simply load the binary files either from a microSD card or directly via a Wifi connection.
  2. Real-time Cartridge Bus Interaction: SidecarT isn't just for ROMs. It's built to interact with the cartridge bus on-the-fly, making data reading and writing seamless. This real-time integration allows for an enriched experience, especially when emulating devices.
  3. Diverse Device Emulation: From hard disks and floppy disks to real-time clocks, keyboards, and mouse devices, SidecarT has you covered. Its advanced capabilities ensure you get an authentic emulation experience across a range of devices.
  4. Open Source & Customizable: At its core, SidecarT is designed for innovation. With open-source code and architecture, you have the freedom to tweak, modify, and expand its functionalities. It's not just an emulator—it's a canvas for all your tech endeavors.
  5. Powered by Raspberry Pi Pico: Thanks to the prowess of the RP2040 microcontroller in the Raspberry Pi Pico, SidecarT delivers exceptional performance and reliability. It's the perfect blend of old-school charm and modern-day tech.
  6. Ever-evolving Capabilities: The world of Atari ST and its series is vast, a major retro platform. SidecarT is built to evolve, ensuring that you're always at the forefront of emulation technology.

How It Works

Getting started with SidecarT is straightforward and intuitive. Here's a step-by-step guide:

  1. Setup the Hardware: Ensure that the Atari ST computer is powered off. Insert the SidecarT device into the Atari ST's lateral cartridge interface and power on the computer.
  2. Initiate SidecarT: Hold down the SELECT button on the SidecarT for more than one second and run the SIDECART.TOS application.
  3. Obtain your ROMs: Using the Atari ST interface, you can easily connect to the web. Dive in, explore, and download your favorite ROMs from the curated lists we've prepared. It's a seamless experience, connecting you directly to HTTP servers for your convenience.
  4. Choose Your Functionality: You'll have an option to select the function of the SidecarT device. If you're looking to emulate a ROM, choose the "ROM Emulator" function, and then select the desired ROM binary from the list.
  5. Start the Emulation: Either reset your Atari ST computer or power cycle it. SidecarT will now operate as the selected emulated ROM cartridge. This behavior persists even if you switch the computer on and off. If you wish to emulate a different ROM or use another function, simply start over from the second step.
  6. Dive In and Enjoy: With everything set up, all that's left is for you to enjoy the immersive experience SidecarT offers!

See it in action



Floppy Emulation and Atari ST database browse


Diagnostics ROMs in Action

Buy a SidecarT



Visit our online shop online shop for more options and configurations.

Frequently Asked Questions

Decades have passed since the discontinuation of the Atari ST/STE/Mega computers. Why, then, should one consider SidecarT?
While emulation tools like STEEM, Hatari, or platforms like MiSTer offer quick and easy software loading and configuration, they can't replicate the authentic experience of the original Atari ST systems. SidecarT bridges this gap. It offers the genuine tactile experience of retro computing while seamlessly integrating modern emulation features. With SidecarT, you're not just reminiscing about the past; you're reliving it with a touch of the present.
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 SidecarT 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.
Can I contribute to the project?
Of course! Please visit the Programming 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!
Where can I find ROM images?
I have gathered some images in this directory. You can download them, or simply connect the SidecarT to your Wi-Fi and browse the catalog online from your Atari ST!


There are several places to contact the community:

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