Neutrino Core

RiptOPL may remain inside APPS/. Its installation folder is independent of Neutrino. Automatic card lookup expects the complete Neutrino installation at mc0:/neutrino/ or mc1:/neutrino/. If Neutrino is nested in another app folder, set its full ELF path explicitly; keep its configuration and modules alongside it.

RiptOPL can hand any individual game to an external Neutrino ELF instead of OPL's built-in EE core. The choice is made per game, leaving other titles on the default OPL core untouched. This is useful for titles that boot more reliably under Neutrino, or when you want fine-grained control over Neutrino's own launch flags.

Neutrino is created by rickgaiser — a "Small, Fast and Modular PS2 Device Emulator". The release package bundles the official latest build as a ready-to-use neutrino/ folder under its AFL-3.0 licence; see Credits for the full attribution. Report launching problems to us and genuine Neutrino bugs upstream.

1. Install Neutrino

The release package includes a complete neutrino/ folder: copy the whole folder to a location RiptOPL can keep available through the handoff. On ordinary non-MMCE setups, mc0:/neutrino/ or mc1:/neutrino/ is supported. A memory card is the last automatic location OPL looks, not the first.

The lookup order is fixed:

A Neutrino Path that is set but unavailable does not strand the launch: the lookup carries on to the game device and the memory cards. If none of them holds a complete install when you launch a game set to the Neutrino core, OPL shows a warning and falls back to the <OPL> core for that launch only.

The old Neutrino Device picker is gone. If it was set to Memory Card or HDD (APA), that choice now appears as the matching Neutrino Path, and until you edit it RiptOPL also tries the other folder/file spellings the picker accepted, because memory cards and APA partitions are case-sensitive. The other old choices load as <not set>.

Network boot exception

The UDPBD / UDPFS feature ships its own bundled Neutrino — a drag-and-drop neutrino/ folder (neutrino.elf plus config/ and modules/) in the release zip, pre-populated with the UDPFS config. Per-game Neutrino use still needs you to supply neutrino.elf at the paths above.

2. Pick the core per game

Where Neutrino works

Unsupported sources fall back to the <OPL> core automatically with an on-screen warning. No manual intervention is needed — OPL detects the format and adjusts.

3. Neutrino Path

Settings → Game Launching → Neutrino Defaults → Neutrino Path is a full-path text field. It shows <not set> until you enter a path, which keeps the automatic lookup. The row is only a preview: selecting it opens the full-size editor, which takes the whole path and scrolls to keep the cursor in view. It replaced the old Neutrino Device picker.

The path may be on a different device from the game. RiptOPL keeps both the game's device and Neutrino's device mounted through the handoff, so it can, for example, load neutrino.elf from mmce0: and launch an APA HDD game. These spellings are accepted:

• BDM devices are matched against what is mounted now. A typed alias (usb:, ata:, mx4sio:, ilink:) searches every mounted device of that family, identified by its driver. Only when none is mounted does RiptOPL load that one driver and wait briefly: 2 s, or 5 s for the internal HDD. mass0: means exactly that slot and loads nothing; slot numbers follow the order devices mounted in.
• APA: hdd:/ resolves only inside the OPL data home that is already mounted. It never mounts another partition, and a nonzero hddN: is refused.
• Network paths start their network stack when no other network protocol is running. The PS2 has one network adapter, so the other protocols stay unavailable until you reboot.
• HTTP URLs cannot be used. HTTP games are streamed by the in-game driver, and there is no http: filesystem to load neutrino.elf from.

The game-device probe accepts the normal NEUTRINO/neutrino.elf / neutrino/neutrino.elf case variants. For MMCE this means, for example, mmce0:/OPL/neutrino/neutrino.elf when OPL is the Prefix Path, then mmce0:/neutrino/neutrino.elf at the bare root.

4. Launch arguments

OPL always builds the mandatory Neutrino arguments automatically from the game and its settings — most of which you never type yourself (-dbc, -logo and -gsm are the three exceptions: forward one yourself and OPL drops its own copy — see the callout at the end of this section, and §5):

Global and per-game extra args

On top of the auto-built arguments you can pass extra Neutrino flags in two places. Both sets are appended after the auto-built arguments; global first, then per-game, so a game can extend or override the global defaults.

• Global (every Neutrino launch): Settings → Game Launching → Neutrino Defaults → Neutrino Advanced Arguments — config key neutrino_args in settings_riptopl.cfg.
• Per game (one title only): Triangle → Game Settings → Neutrino Launch Args — config key $NeutrinoArgs in the game's .cfg.

Arguments are space-separated. Example:

-mt=dvd -gsm=1

Structured Neutrino Args sub-screen

Both the global entry (Settings → Game Launching → Neutrino Defaults → Neutrino Advanced Arguments) and the per-game field (Triangle → Game Settings → Neutrino Launch Args) are buttons that open the same companion sub-screen. It breaks the argument string into named fields — Quick Boot (-qb), Debug Colors (-dbc), PS2 Logo (-logo), Working Dir (-cwd), Config (-cfg), Boot ELF (-elf), ATA0 Image (-ata0), ATA0 ID (-ata0id), ATA1 Image (-ata1), plus a free-form Extra field — reassembles them in a valid canonical order with --b kept last, and writes the result back as a single flat string: the global into neutrino_args, the per-game value into $NeutrinoArgs (each game edited independently).

The canonical reassembly order is: -qb → -dbc → -logo → -cwd → -cfg → -elf → -ata0 → -ata0id → -ata1 → Extra. The Extra slot also collects any flags the parser does not recognise, preserving them verbatim. --b and everything following it is always kept at the tail (those tokens are arguments forwarded to the booted ELF, not to Neutrino itself).

See the exact arguments: Show Launch Arguments

Settings → Game Launching → Neutrino Defaults → Show Launch Arguments (off by default; config key neutrino_show_args) shows the complete argument list just before a Neutrino launch hands over. It is the list the launch passes, not a reconstruction: the auto-built arguments, then yours. Entries are separated by spaces, and a path with spaces in it is shown in quotes so it still reads as one argument.

• Accept launches. Back stays in the menu.
• A list too long for the hand-over (14 entries or 256 bytes) is refused before the preview, as it always is.
• Auto Loading never asks: there is nobody at the menu to answer.

In the arguments sub-screen, a flag typed into Extra that has its own row — -logo, say — moves into that row when you save. It is still sent; it just shows in its row instead of in Extra.

5. Per-game Neutrino Video (-gsm)

When a game's Loader Core is set to Neutrino, a Neutrino Video picker appears in Game Settings. This is the Neutrino-side stand-in for the OPL GSM panel (which is an OPL-core-only feature and is greyed under Neutrino). The picker maps to Neutrino's -gsm flag:

Global default: the same picker also exists in Settings (with its GSM-comp half). Games whose per-game picker is “Default” follow it — so one global change forces e.g. -gsm=1080ix3 for every Neutrino game. An explicit per-game value — including Off — overrides the global.

The picker is the default source for -gsm. If you manually type -gsm=<value> into the Neutrino Launch Args field, that value wins — OPL emits only one -gsm argument, because Neutrino aborts on a duplicate or malformed value.

Mode 7 — fix IOP buffer overrun (-gc=7)

The compat modes list contains a Neutrino-only entry: Mode 7. This maps to -gc=7 and targets a small class of games that overrun an IOP buffer during loading. It is greyed out when the Loader Core is set to <OPL> (the inverse of Modes 4 and 6, which are greyed under Neutrino). Enable it in Game Settings when the game's core is Neutrino.

6. Core-aware per-game settings

The per-game settings screen adapts to the Loader Core chosen for each title, so you only see controls the selected core actually honors.

When Loader Core = Neutrino

• Neutrino Launch Args and Neutrino Video picker are active and editable.
• Compat Modes 4 (Skip Videos) and 6 (Disable IGR) are greyed — these are OPL ee-core features with no Neutrino equivalent. OPL never forwards them.
• Mode 7 is available (Neutrino-only; see above).
• The Configure GSM, Controller Emulation and OSD Settings screens show a "not used with the Neutrino core" message instead of dead controls. Use the Neutrino Video picker for video forcing.
• Cheat Settings works on both cores; only its PS2RD Cheat Image row is greyed, because Neutrino has no cheat-image support. See Cheats with the Neutrino core.
• VMC and the rest of Game Settings remain fully available — VMC is passed to Neutrino as -mc0/-mc1 arguments on BDM devices (USB/iLink/MX4SIO/exFAT HDD/UDPBD), MMCE and UDPFS. The one exception is APA HDD: Neutrino has no APA/pfs backing store to open the .bin from, so the game boots without the VMC and OPL shows a warning (the OPL core honors the same card normally). See VMC with the Neutrino core.
• UDPBD / UDPFS games have no OPL core backend, so the Loader Core selector is locked to Neutrino for them and cannot be changed.

When Loader Core = <OPL>

The screen is unchanged from classic OPL. The Neutrino Launch Args field and Neutrino Video picker are greyed (they are never read on the OPL path). Mode 7 is greyed. Modes 4 and 6 are available as usual.

7. Network boot — UDPBD / UDPFS

UDPBD and UDPFS stream games from a PC over the LAN as network block devices. The block protocols (UDPBD and UDPFS-Image) share the BDM block tab — labelled UDPBD Games or UDPFSBD Games depending on which one is active — while UDPFS-Files is a separate filesystem device with its own UDPFS Games tab. Only one can be active per boot anyway (a single NIC), so the two never appear side by side. Either list carries covers and per-game settings. Because there is no OPL cdvdman backend for network block devices, these games always and only launch via Neutrino — OPL forces the Neutrino core automatically, and if neutrino.elf is missing it warns and returns to the menu (there is no <OPL> fallback).

Full setup, server instructions, and the UDPBD vs UDPFS protocol comparison are on the Network Boot page.

When automatic installation lookup skips a folder

An ELF alone is not a complete Neutrino installation. The resolver checks for config/system.toml or the supported flat-layout system.toml alongside it. Both mc0:/neutrino/neutrino.elf and mc1:/neutrino/neutrino.elf are fallback candidates. Keep the bundled config/ and modules/ folders when copying the installation. A selected valid custom installation or complete installation on the game's device can take precedence over the memory-card fallback.

If manual selection works but automatic lookup fails, report the exact loader revision, active game device, custom path and folder tree. Do not conclude that slot 2 is unsupported from that symptom alone.