Atari ST Fan

Xenon 2 Megablast at 50 frames a second now has its own making-of. It starts with why the 1989 original stopped at 16.7 frames a second, and how the RP2040 in the cartridge became the graphics chip the ST never had. Then the twenty milliseconds the ST gets per frame, measured. Flip on Developer details for the memory maps and the pitfalls we hit on the way. Yes, it was built with AI. No, it was not vibe-coded. It is agentic development on top of plain software engineering: test harnesses and guardrails everywhere, and the work split into iterations, epics, stories and tasks. Claude never hears "go and code". We draw the plan first and test all along. The side effect is a detailed map of every decision, which is how a page like this gets written. Every project from now on gets one. Built on md-framebuffer-template: github.com/sidecartridge/md-… xenon2.sidecartridge.com

Your Atari ST hard-disk game collection has a dirty secret. About two hundred adaptations never ask TOS for a file: they bring their own GEMDOS and read the disk sector by sector, like it's 1991 and nobody is watching. Why does that matter? The original hard disks are forty years old and dying. GEMDRIVE replaces them with modern storage: a folder on the SidecarTridge Multi-device's microSD card that the ST sees as drive C:, the same idea as Hatari's GEMDOS drive with a folder on your PC. Files by name, no sectors. So those games sat there sulking. Not anymore. We started all 1,831 hard-disk adaptations on the 8bitchip.info list from a GEMDOS drive. 1,608 run as they are. For 209 more, we rebuilt their start programs to ask for their files by name. Drop a game's ZIP, exactly as you downloaded it, into the page. It tells you whether the game runs as it is, or patches the ZIP in your browser and hands it back. We host no game files. gemdrive.sidecartridge.com

We have a new place to shout from: SidecarTridge News, our Telegram channel. Firmware releases, new disks in the Atari ST Public Floppy Database, restocks and the occasional board that refuses to behave. If it lands on X, it lands there too, so you can follow along without an X account and without an algorithm deciding what you see. It is a broadcast channel, so no notifications from 400 strangers arguing about TOS versions. Just us, posting when there is something worth posting. Join here: t.me/sidecartridgenews No Telegram? You can read it in any browser: t.me/s/sidecartridgenews And yes, we are also back on Mastodon: oldbytes.space/@sidecartridg…

In 1989 a decent arcade conversion for the ST took a team, a year, a pile of graph paper and somebody's sanity. In 2026 it takes a weekend, a good bunch of Claude tokens and a chat window. And the result is much better. We are not crying, you are crying. Anyway, nine new disks just landed in the Atari ST Public Floppy Database, and most of them were ported with AI coding tools: ZAXXON 1.2, the isometric shooter, for the STE. CRILLION, the 1988 C64 game where the ball bounces by itself and you only get to steer. YARS REVENGE, the 2600 classic, insect warrior against the Qotile. Mario Bros 1.1, the Nintendo arcade original. COMBAT Remastered, the 2600 tank duel with a new coat of paint. DIGDUG 1.1, the arcade digger. Stop the Express, the Hudson Soft Spectrum game, ported by cbragatto with the original graphics and sounds. Bruce Lee, one and two player versions, ported by TjLaZer from Kagesan's Master System version. Full palette and DMA sound on an STE, still happy on a plain ST. The coders of 1989 would need a drink. We'll just play them. One disk each. Real hardware with a SidecarTridge Multidevice or a Gotek style drive, or your favourite emulator. ataristpublicfloppydb.sideca…

Firmware v4.0.0 for the SidecarTridge TOS Emulator and Kickstart Multi ROM is out. The biggest update these boards have had, and it brings a new SWITCHER and a new rescue switcher with it, because the three now speak a new protocol and flatly refuse to talk to their older siblings. Family drama, ROM edition. What's new: No RESCUE button at hand, or the case already closed? Set RESCUE_TIMEOUT in CONFIG.TXT, power on holding RESET, and the board drops into rescue mode by itself. Accelerator board fitted? ACCELERATED_BUS runs every boot at full clock, about 25% faster, so some accelerator boards that used to struggle may now work. Not magic, but worth a try. Your computer always gets something to boot: if the default ROM can't be used, the board starts the rescue ROM instead of a black screen. The ROMEMUL drive is tougher, with a pile of fixes, and the firmware refuses to run on a board it wasn't built for. The SWITCHER has a configuration page (press C) that shows what the board is running with. The rescue switcher has a self-test. Press T and it checks every address and data line, hammers the board with thousands of random reads, then names your machine, monitor and RAM. Press S for a 30 second soak: 265,905 reads and zero errors in the screenshot. Next time someone says "it's the cartridge", you'll have numbers. What's fixed: Mac users with around 29 ROMs or more: the hidden ._ files macOS sprinkles everywhere could wreck the ROM list. Thanks, Apple. Fixed on both sides. The SWITCHER leaked memory every time you went back to the list, and a 512 KB machine eventually crashed. Plugged. Monochrome STs could boot the rescue screen shifted sideways. Straightened. Upgrading from firmware v3.x keeps your ROMs, but you have to replace the SWITCHER and the rescue switcher too, or they'll sulk at an incompatibility screen: docs.sidecartridge.com/sidec… docs.sidecartridge.com/sidec… For board revision 3. Board revisions 1 and 2 stay on firmware v2.1.0. Flash it from your browser: webflash.sidecartridge.com

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…