USB / MX4SIO / iLink

USB mass storage, MX4SIO SD cards (via memory-card slot adapter), and iLink (SBP2 over IEEE 1394) are OPL's three BDM mass-device transports. They share the same filesystem rules, folder layout, and Device Settings controls — all three mount into the massN: namespace and are handled by the Block Device Manager (BDM).

i USB is on by default

RiptOPL ships with USB enabled out of the box. iLink and MX4SIO are off by default; turn them on individually in Device Settings once you have the hardware connected.

The three transports

USB

Standard USB mass storage (the usb BDM driver). Any USB 1.1-compatible flash drive or hard drive works. The PS2's USB controller is USB 1.1 — real-world throughput is roughly 3–4 MB/s, which is enough for DVD-speed game streaming. High-speed USB 2.0 drives are compatible and will simply run at 1.1 speeds.

Enable toggle in Device Settings: USB → On/Off.

MX4SIO

The MX4SIO adapter plugs into the memory-card slot (SIO2 bus) and accepts a standard SD or microSD card. OPL registers it under the sdc / mx4sio BDM driver name. From OPL's perspective the card behaves identically to a USB drive — same folder layout, same filesystem requirements, same per-game settings — but it connects through the memory-card port rather than USB.

Enable toggle in Device Settings: MX4SIO → On/Off.

i MX4SIO and MMCE are different

MX4SIO mounts the SD card directly as a FAT32/exFAT block device (games in DVD/ and CD/ folders). MMCE (SD2PSX, MemCard PRO2) emulates a memory card and also carries an OPL game volume — they use different IOP drivers and separate enable toggles. See MMCE.

iLink (IEEE 1394 / FireWire)

iLink uses the SBP-2 protocol over the PS2's IEEE 1394 (FireWire) port. The BDM driver names for iLink devices are sd / ilink. Supported storage includes SBP-2 compliant hard drives and enclosures. This interface is only present on fat PS2 models that include the iLink port; slim PS2 models do not have an iLink port.

Enable toggle in Device Settings: iLink → On/Off.

Supported filesystems

All three transports support FAT32 and exFAT, both on an MBR partition table. GPT is not supported for BDM mass devices (GPT is supported for the exFAT internal HDD — see Internal HDD).

Filesystem	Max file size	Max volume size	Notes
FAT32	4 GB − 1 byte	~2 TB	Games >4 GB require USBExtreme (.ul) split format
exFAT	Unlimited	Unlimited	Available since OPL v1.2.0 beta rev1880; MBR partition table

i exFAT allocation unit size

When formatting a drive as exFAT, leave Allocation unit size at the Default value in your format tool. Choosing a non-default cluster size can cause compatibility issues.

Folder layout

OPL expects the following directory structure at the root of the drive (or inside the optional BDM Prefix subfolder). OPL creates these folders automatically the first time it runs with the device enabled.

DVD/        PS2 DVD5/DVD9 ISO and ZSO images (also supports >4 GB on exFAT)
CD/         PS2 CD-ROM ISO images (blue-bottom discs)
POPS/       PS1 VCD game images (*.VCD) — listed under the L3 VCD view
CFG/        Per-game configuration files
ART/        Cover art images
VMC/        Virtual Memory Card images
THM/        Theme assets
LNG/        Language files
CHT/        PS2RD cheat files (.cht)
APPS/       Homebrew ELF files

i PS1 games on USB / MX4SIO / iLink

Put your *.VCD files in the POPS/ folder. Press L3 on the device's game page to toggle the VCD (PS1) view. See PS1 Games (VCD) for the full setup — you will also need POPSTARTER on the same device.

Fragmentation

OPL's BDM driver supports up to 64 fragments per file (since OPL v1.2.0 beta rev1893). Games with more than 64 fragments will fail to load. Normal use rarely exceeds this limit, but drives that have been filled incrementally over a long time — especially FAT32 drives — can accumulate heavy fragmentation.

The recommended fix is simple and permanent:

Copy files off

Copy all game files and OPL folders from the drive to a folder on your PC.

Format the drive

Format the drive fresh (FAT32 or exFAT, MBR, default allocation unit size). Do not use a third-party defragmenter — they rearrange data on-disk but the PS2's IOP driver works at the block level and the results are unpredictable.

Copy files back in order

Copy your game files back one at a time, or in one sequential batch, rather than in parallel. Copying files sequentially ensures each file is laid down contiguously. You only need to redo this when fragmentation becomes a problem again.

USBExtreme format (.ul) for FAT32 and large games

FAT32 limits individual files to just under 4 GB. DVD9 games (dual-layer discs) are commonly 6–8 GB — larger than FAT32 can hold in a single file. The USBExtreme (also called USB Advance) format splits these games across multiple files named with a .ul-style scheme and an index file.

OPL reads both plain .ISO files and USBExtreme split sets from the DVD/ folder. If your drive is formatted exFAT you can use plain .ISO or .ZSO files for all games regardless of size. If your drive is FAT32, use USBExtreme for any game over ~4 GB.

Use OPLUtil or USBUtil on PC to split an ISO into USBExtreme format.
The split files and their index belong in the DVD/ folder.
OPL detects USBExtreme sets automatically — no extra setting needed.
ZSO (compressed ISO) is also supported on both FAT32 and exFAT. See ZSO Format.

Enabling devices in Device Settings

Open Device Settings (from the main OPL menu). The relevant controls for this page are:

Setting	What it does	Default
BDM Start Mode	Off / Manual / Auto — controls when OPL scans for mass devices	Manual
USB	Enable/disable the USB mass storage driver	On
iLink	Enable/disable the IEEE 1394 SBP-2 driver	Off
MX4SIO	Enable/disable the MX4SIO SD driver	Off
BDM Cache	Read-ahead cache size in sectors (0–32, default 16)	16
BDM Prefix	Optional subfolder inside the drive root where OPL looks for its folders	(empty)

i Start Mode: Manual vs Auto

Manual (the default) means OPL loads the BDM driver at boot but does not show the game list until you navigate to it — the device is scanned on demand. Auto scans immediately on boot. Off skips the driver entirely; use this if you have no mass devices attached and want the fastest possible boot.

BDM Prefix

The BDM Prefix field lets you store your OPL folder tree inside a subfolder of the drive rather than at the drive root. For example, setting the prefix to OPL tells RiptOPL to look for DVD/, CD/, CFG/, etc. inside mass0:/OPL/ rather than directly at mass0:/.

The same prefix applies to all BDM mass devices (USB, MX4SIO, iLink, exFAT HDD). Leave it empty to use the drive root, which is the most common setup.

Multiple devices at once

OPL can enumerate up to 8 BDM slots (mass0: through mass7:). Each connected device occupies one slot. If you have a USB drive in mass0: and an MX4SIO card in mass1:, both appear as separate game lists (with the slot number shown in the tab label). You do not need to configure them separately — one BDM Mode and one BDM Prefix applies to all slots.

Common issues

Drive is not detected / game list is empty

Confirm the correct transport is enabled in Device Settings (USB / iLink / MX4SIO).
Check that BDM Mode is not set to Disabled.
Make sure the drive uses an MBR partition table (not GPT) and is formatted FAT32 or exFAT.
Verify the folder structure — games must be in DVD/ or CD/ (case-sensitive). If you set a BDM Prefix, games must be under that subfolder.
Try re-seating the drive or adapter, then return to the game list and press Triangle → Refresh.

Game freezes or fails to load (fragmentation)

The 64-fragment limit is the most common cause of load failures on FAT32 drives that have been filled over time. Copy all files to PC, format the drive, and copy them back sequentially. See Fragmentation above.

FAT32 drive cannot hold a large game

DVD9 games over ~4 GB cannot be stored as a single ISO on FAT32. Use USBExtreme format (split via OPLUtil / USBUtil) or reformat the drive as exFAT and use plain ISO files.

MX4SIO not detected

MX4SIO uses the memory-card port. Make sure MX4SIO is enabled in Device Settings. Note that MX4SIO and a physical memory card (or MMCE device) cannot share the same slot simultaneously.

iLink not detected

iLink is only available on larger PS2 models. Slim PS2 (PS2 Slim / 7000x and later) do not have the iLink port. If your model has the port, make sure iLink is enabled in Device Settings and the drive is SBP-2 compliant.