The SidecarT as a GPU

In 1990 Andreas Kromke (the author of KAOS TOS, the heavily modified and performance-tuned TOS for the ST range) looked at TOS and said: one program at a time? No, thanks. Mag!X was born, later MagiC: a real multitasking OS for the Atari ST, with several GEM apps running side by side in their own windows, and still happy with software written for TOS. It was a commercial product for years. Then Kromke did something few authors do: he opened the complete sources under the GPLv3. And this year he shipped MagiC 6.30 for Atari computers. In 2026. On a 68000. Respect. Normally MagiC boots from disk: TOS starts first, then a loader pulls the kernel into RAM. We thought that was a waste of perfectly good RAM, so we built the MagiC ROM Builder. It turns MagiC 6.30 into a 256 KB ROM image that boots in place of TOS, plus the boot floppy or hard disk files for its desktop. Everything happens in your browser, nothing to install. Flash it with the SidecarTridge TOS Emulator on an STE or Mega STE, or on an ST or Mega ST with the 256KB Decoder. No TOS needed, around 240 KB more free RAM, and it boots straight into a multitasking desktop. Build your ROM: magic.sidecartridge.com/ MagiC sources by Andreas Kromke: gitlab.com/AndreasK/Atari-Ma…

Unlike the Croissant, the Soufflè is a design I actually enjoyed. This one has real hardware meat on its bones. First boss: the USB hub. Getting a hub to play nicely with the USB port of a Raspberry Pi Pico 2 W is harder than it sounds, because not all of them work. Learning how those tiny, hyper-specialised hub controllers actually think turned out to be a lot of fun. Second boss: power. Every USB device you plug in wants its share, and the Atari has to feed all of them. On a Mega ST that's no big deal. On a Mega STE or a TT it is, because those machines have a fuse to stop exactly this kind of party. So the USB ports are current-limited to keep your computer from being drained. Third boss: two power sources. All my circuits protect against dual voltage input, and here I picked a simple rule. Powered from the Atari, the USB hub is on. Powered from the Pico 2 W's micro USB, the hub is off and the port stays free for things like firmware updates. All this juggling comes with one rule on the Mega STE: Bluetooth and the USB hub at the same time are forbidden, because together they exceed the theoretical limit the machine can supply and its fuse would blow. Theoretical, because I never managed to blow it. I might add a "Suicidal mode" for anyone brave enough to try it on their own Mega STE. Mega ST owners, you're welcome to it too. As usual, the source code: The emulator itself, with the original HD6301 code: github.com/sidecartridge/rp2… The loader, a variant of the Multi-device's Booster: github.com/sidecartridge/rp2… And the video, for anyone who still doesn't know what it is: youtube.com/watch?v=k-8jHeQD…

I almost didn't release the Croissant. As a hardware design it's not exactly rocket science. The schematics are in the docs, so anyone can build their own. The interesting part is the software, and that stands on the shoulders of a brilliant idea by fieldofcows: emulating the Hitachi 6301, the chip that handles keyboard, mouse and joystick on the Atari ST/STE, inside a Raspberry Pi Pico. That code was the seed for both Croissant and Soufflè, which share the same codebase. So what pushed me to finish it? Someone kept dropping into the old SidecarTridge Discord asking how to build his own Croissant. Fine by me, helping people build stuff is half the fun. A few weeks later he posted his version on Atari Forum: Claude Code 2025 vibe-coded, with a PCB featuring some truly "creative" choices, thanking every body one by one for their help. Everyone except me. The best part: to get Bluetooth working smoothly with every device, the Bluepad32 library needed some surgery. I did that surgery. He was running my version of the library and he had no idea. In a scene where nobody makes money and recognition is the only currency, that one stung. Add the growing dose of insults on Discord and the decision was easy: goodbye, Discord. Hello, finished Croissant. Confession: I never enjoyed designing this one, and it turned out to be one of our best sellers. Life. My favourite is the Soufflè, that one was a real challenge. Bonus tip most people don't know: Croissant also works with USB devices. Flash the Soufflè firmware and plug a USB hub into the Pico W's micro USB port. Here's the video for anyone who still doesn't know what it is: youtube.com/watch?v=mTe4EGKS…

Dragon's Lair is here for the SidecarTridge Multi-device. In 1983 it needed a laserdisc player the size of a fridge and ate your quarters faster than Singe eats knights. In 2026 it fits in your Atari ST's cartridge slot. Yes, really. The whole Don Bluth cartoon, full screen at 25 pictures a second, with sound, on a plain ST, STE, Mega ST or Mega STE. No laserdisc. No coin slot. No mercy. Just you, a joystick and a dragon who has been waiting 43 years for a rematch. Personal note: at 15 I was the undisputed king of that cabinet. I had every single move burned into my brain and could finish (well... sort of) the game with my eyes half closed. Now I'm closer to 60 than to 50, and some mornings I can't remember where I left my glasses. So I built oldies mode: the game shows you the next move before Dirk turns into a pile of bones. Proudly made for those of us whose RAM is starting to leak. Watch Dirk die so you don't have to: youtube.com/watch?v=-Uulwd8h… How to set it up: docs.sidecartridge.com/sidec… Grab your sword. Daphne is not going to rescue herself. Well, she could. But it's 1983.

Drives Emulator v1.2.0 for the SidecarTridge Multi-device is out, and it's all about the unglamorous stuff that makes your Atari stop complaining. This is a stabilization build. We found a nasty one in the hard disk emulation: when a write to the microSD card timed out, every request after it had to be sent all over again. Fixing it means files no longer get mangled on slow cards, and writing from your Atari is now almost twice as fast. TOS 1.04 and 1.06 also stop hanging the desktop thanks to a built-in pool fix, and copying files to the card over USB is up to 9 times faster. Then there's the Falcon. Not the most popular machine Atari ever made, but by far the most requested one in our inbox. Falcon owners, you were few, but you were loud. Hard disks, floppies and the clock now work on the Falcon with TOS 4.04. The Mega STE keeps its 16 MHz and cache too, and every Atari finally shows the right date. Walkthrough video: youtube.com/watch?v=CLtQs595… Docs and full changelog: docs.sidecartridge.com/sidec…