diff --git a/retro/atari-mega-st-fleet/index.njk b/retro/atari-mega-st-fleet/index.njk
index f35a52e..6c74da2 100644
--- a/retro/atari-mega-st-fleet/index.njk
+++ b/retro/atari-mega-st-fleet/index.njk
@@ -14,7 +14,7 @@ parent: "/retro/"
 <h2>The Lineup</h2>
 <ul>
 <li><strong>The heirloom machine</strong>, kept as close to factory-original as possible, running the stock TOS 1.04 and a classic floppy drive. Its job is to be a baseline reference: if something breaks on a modded machine, this one proves the fault isn't in the software.</li>
-<li><strong>The "Low" machine</strong>, a bargain-bin Mega ST 4 rebuilt with a <a href="/retro/storm-cloudy/">Cloudy/Storm ST combo</a> for TOS switching and extra FastRAM, a Gotek floppy emulator, an UltraSatan hard disk emulator, and a SidecarTridge multi-device for ROM, floppy, and Wi-Fi tricks. This is the demo- and game-machine, optimized for fast disk-image swapping rather than serious productivity.</li>
+<li><strong>The "Low" machine</strong>, a bargain-bin Mega ST 4 rebuilt with a <a href="/retro/storm-cloudy/">Cloudy/Storm ST combo</a> for TOS switching and extra FastRAM, a Gotek floppy emulator, an UltraSatan hard disk emulator, and a <a href="/retro/sidecartridge/">SidecarTridge multi-device</a> for ROM, floppy, and Wi-Fi tricks. This is the demo- and game-machine, optimized for fast disk-image swapping rather than serious productivity.</li>
 <li><strong>The "High" machine</strong>, the workstation build. A <a href="/retro/monsterboard/">MonSTerBoard</a> adds 8MB of AltRAM, IDE storage, and flashable TOS (currently TOS 2.06), running Geneva for real multitasking. An <a href="/retro/et4000-experiment/">ET4000 graphics card</a> drives a dedicated monitor for higher resolutions. A <a href="/retro/netusb/">NetUSBee</a> adapter and original Atari keyboard/mouse round it out.</li>
 <li><strong>The spare Mega ST 2</strong>, a reserve and donor machine, kept in largely original condition, used to safely test upgrades before they go into the "real" machines.</li>
 </ul>
diff --git a/retro/index.njk b/retro/index.njk
index e761b4c..b212a7c 100644
--- a/retro/index.njk
+++ b/retro/index.njk
@@ -22,6 +22,9 @@ sections:
       - title: "🌀 Storm ST & Cloudy ST"
         summary: "Adding 8 MB Alt-RAM and flashable TOS to the Mega ST, switching between EmuTOS and TOS 1.04."
         href: "/retro/storm-cloudy/"
+      - title: "💳 SidecarTridge Multi-device"
+        summary: "An apps platform in a cartridge, adding Wi-Fi, ROM emulation and floppy/hard-disk images to the Mega ST 4 'Low'."
+        href: "/retro/sidecartridge/"
       - title: "🧠 MonSTerBoard"
         summary: "How the MonSTerBoard turns the Mega ST 4 'High' into a workstation with 8 MB TT-RAM, dual IDE and flashable TOS."
         href: "/retro/monsterboard/"
diff --git a/retro/sidecartridge/index.njk b/retro/sidecartridge/index.njk
new file mode 100644
index 0000000..ef97a3f
--- /dev/null
+++ b/retro/sidecartridge/index.njk
@@ -0,0 +1,34 @@
+---
+title: "SidecarTridge Multi-device: An Apps Platform in a Cartridge"
+section: "retro"
+tags: "retro"
+description: "How the SidecarTridge Multi-device turns the cartridge port of my Atari Mega ST 4 'Low' into an apps platform for floppy, hard disk, ROM and Wi-Fi."
+layout: base.njk
+parent: "/retro/"
+---
+<h1>SidecarTridge Multi-device: An Apps Platform in a Cartridge</h1>
+<div class="detail-content">
+
+<p>My <a href="/retro/atari-mega-st-fleet/">Mega ST 4 "Low"</a> 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.</p>
+
+<h2>What it does</h2>
+<p>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:</p>
+<ul>
+<li><strong>ROM emulation</strong>, load 64K or 128K cartridge ROMs from microSD or over Wi-Fi and swap them on the fly.</li>
+<li><strong>Drives emulator</strong>, floppy and hard-disk emulation from a microSD card, so you can boot any image without a mechanical floppy drive.</li>
+<li><strong>Browser</strong>, search floppy images directly from the ST over Wi-Fi and boot them, with no PC in the middle.</li>
+<li><strong>MIDI-to-IP</strong>, bridge the ST's MIDI port to the internet, so networked MIDI works against players anywhere.</li>
+<li><strong>Real-time clock</strong>, plus other apps, all switchable without reflashing.</li>
+</ul>
+
+<h2>An apps platform, not just an emulator</h2>
+<p>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.</p>
+
+<h2>How it works</h2>
+<p>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 <a href="/retro/storm-cloudy/">Cloudy/Storm ST combo</a> and the Gotek for disk-image swapping.</p>
+
+<h2>Sources</h2>
+<ul>
+<li><a href="https://sidecartridge.com/products/sidecartridge-multidevice-atari-st/" target="_blank">SidecarTridge Multi-device for Atari ST - official product page</a></li>
+</ul>
+</div>