Neutrino

Neutrino Core

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.

These features are specific to RiptOPL

The Loader Core selector, the Neutrino Path setting, the structured Launch Args sub-screen, and the per-game Neutrino Video picker are all additions in this fork. They do not exist in stock OPL or wOPL.

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.

MMCE users: place Neutrino on the MMCE game device

If you use Send GameID on Launch, put the complete folder on mmceN: rather than relying on the same slot's mcN: view: use mmceN:/neutrino/, or put neutrino/ under the configured MMCE Prefix Path. The GameID command switches the emulated memory-card view. An mcN:-hosted Neutrino would be displaced by that switch, so RiptOPL detects the collision and skips the GameID switch for that launch to keep the loader readable. An mmceN: install is not affected, so the per-game card switch can still occur. The automatic lookup deliberately probes the active game device before the memory cards.

The lookup order is fixed:

Priority	Where OPL looks
1	Neutrino Path, when it is set (Settings → Game Launching → Neutrino Defaults) — see §3
2	The active game's own device: <games prefix>/neutrino/, then <device root>/neutrino/. For an APA HDD game this is the OPL data home already mounted on pfs0: (+OPL or __common/OPL)
3	mc0: / mc1:: NEUTRINO/neutrino.elf and its lowercase / NEUTRINO.ELF variants

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.

Upgrading with Neutrino on the APA HDD

Older builds also searched the APA HDD's OPL data home automatically for games on other devices. That search is gone. If Neutrino lives in hdd0:/+OPL/neutrino/ or hdd0:/__common/OPL/neutrino/ and you use it for USB, MMCE or network games, set Neutrino Path to hdd:/neutrino/neutrino.elf. HDD games still find it through the game-device tier.

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

Open Game Settings

Highlight a game, press Triangle and choose Game Settings.

Set Loader Core

Change Loader Core to Neutrino. The other option is <OPL> (the built-in core; default for every game).

Save

Save. The selection is written as $CoreLoader in that game's .cfg file.

Where Neutrino works

Game source	Neutrino?
USB / MX4SIO	Yes
iLink / IEEE 1394 (FAT PS2 models only)	Supported and wired; the post-2692 build adds quick boot for RiptOPL's inherited-stack handoff and is pending hardware retest
Internal ATA (BDM block device)	Yes
Internal HDD (APA partition → HDL)	Yes
MMCE (SD2PSX / MemCard PRO2)	Yes
UDPBD / UDPFS (network block device)	Yes — and required; no OPL core backend exists for these (see Network Boot). Both work on a real PS2; the UDPBD test (2026-09-26) used every Neutrino setting at its default.
SMB / Ethernet	No — falls back to <OPL>
USB Extreme split images (.ul)	No — falls back to <OPL>
Compressed ISO (.zso)	No — falls back to <OPL>

Revision 2692 iLink result

On an SCPH-39001, Neutrino failed from iLink in all four SDK flavours. Revision 2692 emitted the documented -bsd=ilink token but did not add -qb. RiptOPL's bridge deliberately preserves the mounted iLink environment, while Neutrino documents -qb as direct entry into its load environment, so that omission is a source-confirmed handoff mismatch consistent with the failure. The post-2692 correction below still needs a hardware pass to prove whether it was the complete cause; this page does not call it a pass yet.

i Upstream rates iLink lowest of every backend

Neutrino's own backend table scores iLink / IEEE1394 device compatibility at 10, against 80 for USB, 60 for MX4SIO and 100 for MMCE, ATA, UDPBD and UDPFS, and lists it for FAT PS2 models only. A passing -qb retest is therefore necessary but may not be sufficient — some iLink enclosures are expected to fail upstream as well.

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.

PS1 games are a separate path

PlayStation 1 titles always boot through their own core — POPSTARTER.ELF for *.VCD, ember.elf for Ember titles — never OPL's core and never Neutrino. The Loader Core selector is locked and has no effect for PS1 games. See PS1 Games (VCD).

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:

Meaning	Accepted examples
USB	usb:/..., usb0:/...
Internal exFAT HDD	ata:/..., ata0:/...
MX4SIO	mx4:/..., mx4sio:/..., massX:/...
iLink	ilink:/...
A mounted BDM slot	mass:/... (every mounted slot), mass0:/... (that one slot)
MMCE	mmce:/..., mmce0:/..., mmce1:/...
Memory card	mc:/..., mc?:/..., mc0:/..., mc1:/...
SMB share	smb:/...
UDPFS files	udpfs:/...
UDPFS / UDPBD disk	udpfsd:/..., udpfsbd:/..., udpbd:/...
APA HDD OPL data home	hdd:/..., hdd0:/...
Mounted PFS partition	pfs:/..., pfs0:/...

• 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):

Auto-emitted argument	When emitted
-bsd=<usb|ilink|mx4sio|ata|mmce|udpbd|udpfsbd|udpfs>	Always (the storage backend)
-bsdfs=hdl	Internal HDD (APA) only
-bsdfs=<exfat|hdl|bd>	Only when the game's Neutrino Filesystem is set off Auto, or when you type -bsdfs= into the arguments — a typed one wins over the picker (per-game arguments over global ones, the last one wins, nothing after --b). Block devices only, never MMCE/UDPFS. hdl/bd also reshape -dvd to hdl:/bdfs:, and a typed -dvd= wins if it is forwarded (a long argument list can drop it). bd names the drive as <driver><N>p0 (a second USB stick is usb1p0) from the device number the drive reported; if it never reported one, the launch is refused while the menu is still up rather than guessed as device 0 — whether bd was picked or typed, even beside a typed -dvd=. ATA is exempt (one device, always 0).
-dvd=<path> / -dvd=hdl:<partition>	Always (the game image or partition)
-qb	USB, iLink, UDPBD and both UDPFS legs — the same set NHDDL uses (every mode except HDL). RiptOPL's no-reset bridge preserves the mounted BDM/UDPFS environment; quick boot enters Neutrino's load environment without resetting that inherited stack away. Without it, a UDPBD launch reconnected on its own after the reset, read the image's partition table and never reached the game. An active user-supplied copy is never duplicated.
-gc=<modes>	Only when OPL compat modes are set for the game
-dbc	Only when Debug Colors is enabled
-logo	Only when PS2 Logo is enabled
-gsm=<mode>	Only when a Neutrino Video mode resolves — the per-game picker, or the global Settings → Game Launching → Neutrino Video default when the per-game picker is “Default” (see §5)
-mc0=<path> / -mc1=<path>	Only when a per-game VMC is configured for that slot

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 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

Editing long argument strings

Both the global Neutrino Advanced Arguments and the per-game Neutrino Launch Args open a structured sub-screen (see below) whose individual fields each hold up to 31 visible characters. If you need a longer value in a single field, edit neutrino_args (global, in settings_riptopl.cfg) or $NeutrinoArgs (per game, in the game's .cfg) directly — OPL reads and forwards the full string at launch. The editor preserves every field you do not touch at its full stored length, so opening and closing the dialog never truncates a hand-edited value.

Structured Neutrino Args sub-screen

Both the global entry (Settings → Game Launching → 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).

Field	Argument emitted	Notes
Quick Boot (-qb)	-qb	Enter Neutrino's load environment directly; emitted first if enabled and supplied automatically for USB, iLink, UDPBD and UDPFS
Debug Colors (-dbc)	-dbc	Neutrino's debug colour output; forwarding it here suppresses OPL's own auto-emitted copy
PS2 Logo (-logo)	-logo	Show the PS2 logo; forwarding it here suppresses OPL's own auto-emitted copy
Working Dir (-cwd)	-cwd=<path>	Override Neutrino's working directory
Config (-cfg)	-cfg=<path>	Point Neutrino at an alternate config file
Boot ELF (-elf)	-elf=<path>	Launch a different ELF instead of the disc boot ELF
ATA0 Image (-ata0)	-ata0=<path>	Override the primary ATA image path
ATA0 ID	-ata0id=<id>	Override the ATA0 device ID string
ATA1 Image (-ata1)	-ata1=<path>	Override the secondary ATA image path
Extra	(verbatim)	Any other flags, including --b and everything after it (passed to the booted ELF); placed last

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).

Auto-emitted flags are never typed

-bsd, -dvd, -gc, and -mc0/-mc1 are always constructed from the game settings by OPL. Do not enter them in the Extra field or the Launch Args text box — doing so produces a duplicate that Neutrino may reject or misinterpret. Use the dedicated UI controls (compat modes, VMC slots, etc.) to set those values instead.

-dbc, -logo, and -gsm are the exceptions: they have dedicated controls (the Debug Colors and PS2 Logo toggles in the args sub-screen, and the Neutrino Video picker), and if you do forward one of them yourself OPL suppresses its own auto-emitted copy so exactly one reaches Neutrino. A copy disabled with a leading $ does not count as forwarded, so OPL still emits its own in that case.

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:

Picker value	Neutrino flag emitted
Off (default)	(nothing emitted)
240p	-gsm=fp1
480p	-gsm=fp2
1080i x1	-gsm=1080ix1
1080i x2	-gsm=1080ix2
1080i x3	-gsm=1080ix3
Default	follows the global Settings → Game Launching → Neutrino Video value (no per-game key saved)

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.

i The “1080p impression” trick

On 1080-class displays, 1080i x3 (-gsm=1080ix3) is the community workaround for progressive-looking output — the same effect previously reached by launching Neutrino from PS2BBLE/OSDmenu with -gsm=1080ix3. Set it per game, or globally and leave games on “Default”. True 1080p is not one of Neutrino's -gsm modes — its option remains 1080i. RiptOPL's native OPL core separately provides a hardware-confirmed forced-progressive 1080p GSM mode in every standard loader; it is guarded by a three-step confirmation, with Triangle + Cross at console boot changing only the menu to 480p (Triangle + Circle forces the interlaced Auto mode instead). A game video override must be changed in game settings; the display/connection must accept 480p for menu recovery.

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).
• Download Defaults is greyed — it pulls OPL bitmask data that does not map to -gc.
• The Configure GSM, Cheat Settings, 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.
• 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.

What does Neutrino actually honor from OPL's per-game settings?

Neutrino honors: the storage backend + image path (-bsd / -dvd, automatic), the compat mode subset that maps to -gc (Modes 1/2/3/5/7), VMC via -mc0/-mc1 (BDM/MMCE/UDPFS — not APA HDD), -logo (PS2 logo), -dbc (debug colors), the Neutrino Video picker (-gsm; per-game with a global default in Settings), and the free-text Neutrino Launch Args field. It does not honor: Cheats (OPL patches EE RAM), OPL GSM (OPL patches the GS registers), IGR (OPL's in-game reset hook), PADEMU (OPL's USB gamepad emulation), or OSD Language — all are OPL-embedded-core features with no Neutrino equivalent.

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.

• Network Boot UDPBD & UDPFS setup, server requirements, static IP

• Per-game Settings Every per-game option explained

• VMC Virtual memory cards — works under Neutrino too

• PS1 Games (VCD) Separate path — always POPSTARTER, never Neutrino

Detailed reference: Neutrino reference.

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Source: neutrino.html @ 2c3e24ed7d44. Read on the documentation website.