MX4SIO (microSD)

MX4SIO is a microSD adapter that plugs into the PlayStation 2's memory-card slot and talks to the console over its SIO2 bus. This build of SMS mounts the card as a massN: device and plays media straight off it — video, audio and pictures — reliably. Working MX4SIO playback is the headline feature of this fork, and the card gets its own device icon in the menu so you can tell it apart from USB.

What MX4SIO is

An MX4SIO adapter takes a microSD card and presents it to the PS2 through the memory-card slot, communicating over the console's SIO2 controller bus (the same bus the pad and memory card use). To SMS the card looks like any other BDM (Block Device Manager) mass-storage volume: it is mounted from the FAT/exFAT layer and surfaces as massN:, exactly the abstraction USB, exFAT-over-ATA and i.LINK all share. That means SMS does not need a special "MX4SIO file browser" — it simply browses the card's raw filesystem and plays whatever media files it finds, wherever they sit. There is no mandatory folder tree to build.

In the device menu the card appears with the same massN: naming as the other mass devices, where N is 0, 1, 2… depending on what else is mounted. Point the browser at the card, walk into your folders, and open a file.

Why it is the headline feature

Plenty of PS2 tools can mount an MX4SIO card and list its directories — but that is the easy part. A media player is different: it streams large reads continuously while the rest of the console is busy decoding audio, driving the GUI and polling the pad. Under exactly those conditions, earlier attempts to use MX4SIO in SMS would mount the card and show the file list, then stall the moment you tried to actually play a file.

This build fixes that. Video and audio now play smoothly from a microSD in an MX4SIO adapter — the same experience you get from USB or the internal HDD. To make it a first-class citizen, MX4SIO also gets:

• Its own device icon in the top device bar, visually distinct from the USB icon, so you always know which card you are browsing.
• An Autostart MX4SIO toggle in the settings menu, so it can come up automatically at boot if you want it to.
• A Start MX4SIO now item that appears when the driver is not yet running, so you can bring the card online on demand without rebooting.

Compatibility

SMS reads the card through the standard FAT/exFAT layer, so a microSD formatted as FAT32 or exFAT will mount. FAT32 is the safe, universally-compatible choice; exFAT lets you use larger cards and store files bigger than 4 GB. Either way, the media files themselves must be a format SMS can play — see Video, Audio and Pictures for the full list (MPEG-4 Part 2 AVI, mp4v MP4, MPEG-1/2 program streams, MP2/MP3, AAC, AC3, FLAC, OGG, WMA, JPEG, and so on).

Preparing the card

Enabling MX4SIO

On a fresh install SMS starts nothing automatically — you switch on the devices you want. There are two ways to bring MX4SIO up.

Autostart MX4SIO

In the settings menu, turn on Autostart MX4SIO. From then on SMS loads the MX4SIO driver at boot and the card is ready to browse as soon as the desktop appears. This is the option to use if MX4SIO is your everyday media source. Your choice is saved with the rest of your settings (see Settings), so it sticks across reboots.

Start MX4SIO now

If MX4SIO is not currently running, SMS also shows a Start MX4SIO now item so you can bring the card online on demand — no reboot needed. This is handy when you didn't autostart it but decided you want it this session, or when you have just seated the adapter.

Pick it in the device menu

Once MX4SIO is running, the card shows up in the device menu (the top row of device icons) with its own icon, separate from USB. Use Left/Right to land on it, then press Down to drop into the file list and start browsing. From there it behaves like any SMS browser: Up/Down to move, L1/L2 to page-scroll, Cross to open a file or folder, and Triangle to step up a level (file list → parent → back to the device menu).

MX4SIO vs MMCE

This is the one gotcha worth internalising. Both MX4SIO and MMCE devices physically occupy a memory-card slot and talk over the SIO2 bus — so SMS can only drive one of them at a time. They are not interchangeable, either: they use different drivers and mount under different names.

Rule of thumb: turn on Autostart for the adapter you actually own, and leave the other off. If your device is an SD2PSX or MemCard PRO2, use the MMCE page. If it's a plain SD-over-SIO2 adapter, you're in the right place.

How it works (at a glance)

You don't need to know any of this to use MX4SIO — but in short: a continuously-streaming media player asks a lot more of an SD-over-SIO2 card than a lightweight file manager does, because it reads constantly while also decoding audio and driving the GUI. This build carries the MX4SIO driver and access-path hardening needed to keep playback reliable under exactly those demands. It is entirely automatic — there is nothing to enable, tune, or configure.

Notes & tips

• MX4SIO reads any format SMS can play — it is a storage device, not a format. Point the browser at your files and open them like on any other device.
• You can browse into any folder structure; there is no mandatory layout. Keep .srt/.sub subtitle files beside their video.
• Enable either MX4SIO or MMCE, never both — they share the SIO2 slot bus.
• Prefer FAT32 for maximum compatibility; use exFAT for very large cards or files over 4 GB.
• If a specific card acts up, try another known-good microSD before assuming a software fault.
• Your Autostart MX4SIO choice is saved with your settings and persists across reboots — see Settings for where the config lives.