SidecarTridge Multi-device: An Apps Platform in a Cartridge
My Mega ST 4 "Low" machine uses a SidecarTridge Multi-device, a small board with a Raspberry Pi Pico W inside that plugs into the cartridge port and turns the Atari into an apps platform. It brings Wi-Fi and a microSD slot to the machine and runs a growing catalog of modular apps, no soldering and no internal mods required. I bought the original Revision 0 back in late 2023/early 2024, and I've since picked up the new Revision 3 as well.
What it does
The SidecarTridge Multi-device works in any Atari ST, STE, Mega, TT or Falcon. A Raspberry Pi Pico W inside brings Wi-Fi and a microSD slot, and the board interacts with the cartridge bus in real time to emulate a range of devices:
- ROM emulation, load 64K or 128K cartridge ROMs from microSD or over Wi-Fi and swap them on the fly.
- Drives emulator, floppy and hard-disk emulation from a microSD card, so you can boot any image without a mechanical floppy drive.
- Browser, search floppy images directly from the ST over Wi-Fi and boot them, with no PC in the middle.
- MIDI-to-IP, bridge the ST's MIDI port to the internet, so networked MIDI works against players anywhere.
- Real-time clock, plus other apps, all switchable without reflashing.
An apps platform, not just an emulator
Firmware V2 reworks the device into an apps platform. Instead of one fixed mode, it runs a catalog of modular apps you can switch between in seconds, with over-the-air updates and per-app configuration. The hardware and firmware are open source on GitHub, so the community keeps adding new apps and the Atari keeps gaining capabilities.
How it works
Setup takes about ten minutes. Slide the Multi-device into the cartridge port, power on, and on first boot it exposes its own SIDECART Wi-Fi network. You join it from a phone or laptop, pick your home Wi-Fi, and from then on the device joins your network automatically. Once connected it shows a QR code with its IP, which opens a web UI listing every installed app, and you pick what your ST should become. On the "Low" machine I use it for the ROM and floppy side of things, alongside the Cloudy/Storm ST combo and the Gotek for disk-image swapping.
Revision 0 vs. Revision 3
My Revision 0 is the very first version sold at the end of 2023/start of 2024, and it's the one in use on the "Low" machine. The new Revision 3 is a complete redesign that addresses feedback from early buyers. Functionally both run the same firmware and do the same things, but the v3 is noticeably improved:
- Size and stability, the Rev 0 was a long, wide 2-layer board that stuck out and could flex if knocked. The v3 is a much more compact 4-layer board that sits more discreetly and doesn't flex.
- Signal quality, the Rev 0 used simple tinned (HASL) contacts, which can oxidise over time on the sensitive Mega ST bus and cause sudden crashes. The v3 uses a high-quality ENIG gold finish plus two inner copper layers for cleaner power, so transfers run flawlessly.
- Wi-Fi reception, on the Rev 0 the antenna sat over normal traces that dampened the radio signal, so the connection could drop if the ST was in a bad spot. The v3 has a copper clearance area under the antenna for a stronger, more stable connection.
- Power draw, the Rev 0 loads the aging 5V rail a bit more. The v3 was optimised to draw noticeably less and run more efficiently.
- Layout and Pico W mounting, on the Rev 0 the buttons and connectors were in the original spots and the Pico W had to be soldered on tall pin headers. The v3 repositions the buttons ergonomically and lets the Pico W be soldered flat, plus adds JST sockets for external buttons without soldering.
My Setup
The original Revision 0 SidecarTridge is in use on the Mega ST 4 "Low" machine. The new Revision 3 I've bought but not yet installed, so it's still sitting alongside the other uninstalled extensions until I decide where to use it.