SidecarTridge® 256KB Decoder + TOS Emulator for Atari ST/MegaST

Warning: you need soldering skills to install this device

Unlock enhanced functionality on your Atari ST or Mega ST

This kit enables seamless use of a wide range of TOS versions, including 256KB ROMs typically available only on Atari STe and Mega STe models. By decoding 256KB ROMs, the SidecarTridge setup expands compatibility beyond the standard 192KB versions, allowing you to run TOS versions up to 2.06 without physically swapping ROM chips.

Product Overview

• 256KB Decoder: Installed directly on the Motorola 68000 CPU, this decoder enables access to 256KB ROMs by generating synthetic signals that interface with the SidecarTridge TOS Emulator.
• SidecarTridge TOS Emulator: Provides a flexible platform to run multiple TOS versions and custom ROMs, all accessible with ease.

Why Choose the 256KB ROM Decoder + SidecarTridge TOS Emulator?

This setup offers unparalleled flexibility, letting Atari enthusiasts and developers run a broad range of TOS versions originally designed for later models—all without the hassle of physical ROM swaps. With emulated internal ROMs and 256KB decoding, you can seamlessly switch between TOS versions and explore various operating systems and applications on your Atari ST or Mega ST.

How It Works

The 256KB Decoder and SidecarTridge TOS Emulator work together to give your system access to the full range of TOS versions:

• Address Signal Generation: The decoder synthesizes address signals for the $E00000 range, allowing the CPU to access the expanded 256KB ROM space.
• Chip Enable (CE) Signal Creation: A synthetic CE signal ensures the ROM is activated only when the CPU accesses the specified range, maintaining efficient data flow.

The kit includes both the 256KB Decoder and the SidecarTridge TOS Emulator, providing everything you need to get started. For a deeper look at the features of the SidecarTridge TOS Emulator, Visit the documentation site of the product.

Do you want to learn more? Visit our documentation site!

Find the Right Kit for Your Atari ST

Ready to upgrade? Ensure compatibility by checking your Atari ST motherboard model. Locate the model number inside the case, then refer to our Compatibility Guide. Determine if your ROM chips are plugged or soldered. Once confirmed, choose the perfect SidecarTridge TOS emulator kit for your setup.

For any questions or assistance, visit our Contact Page.

Kit content

The kit contains the following parts:

1. SidecarTridge 256KB Decoder Board
2. SidecarTridge ROM Emulator Board
3. SidecarTridge Atari ST Carrier Board. The ROM Emulator Board is soldered onto this carrier board.
4. RESCUE cable and push button
5. 6-pin flat cable (20cm for MegaST models, 10CM for ST models)

You will also need the following items:

1. USB-C cable: for connecting the SidecarTridge TOS emulator to a computer for firmware updates and TOS image transfers. You can buy a USB-C to USB-C or USB-A to USB-C cables in our online shop if you do not already own one.
2. SWITCHER.TOS application. The app is downloadable from our website and available inside the volume of the device, but it's also in a 3 1/2 floppy disk with the SWITCHER.TOS application.