jpolo1224
4d97b6cdf5
A paletted replacement is keyed on TEX0 hash AND palette hash, so a pack only applies while the game asks for a palette its packer happened to dump. Persona 3 FES lands exactly there: the pack carries several palette variants of each glyph and the game asks for one that is not among them, so every glyph misses while the unpaletted art around it replaces fine -- 189 hits against 323 misses, which is why the scene looked right and the text did not. With this, 441 against 71, and none of the remainder are palette mismatches. Lowest palette hash, deliberately. It is arbitrary but STABLE: the same glyph resolves to the same file on every draw and every run, so text renders in one consistent colour. Choosing by file mtime was tried and was worse in a way worth recording -- different glyphs won different variants and the text came out multicoloured. The colour can still be wrong, since the replacement image has the packer's palette baked in and there is no recolouring it. That is the trade, and it is the right way round: a mod that applies in the wrong shade beats one that does not apply at all. This does NOT explain why the pack matched on 2.6.6. That is a separate finding and still open: the same glyph at the same address with the same palette hashes differently now (2.6.6 asks 85076d2a533c0128, current asks f0576dc2f0bb17d5), with TBP0, TBW, PSM, TW/TH, region and lod all identical between them. The bytes in GS local memory differ, which is upstream of texture replacement entirely.
ARMSX2 — Native ARM64 JIT Fork of PCSX2
ARMSX2 is a free and open-source PlayStation 2 (PS2) emulator based on PCSX2. Its purpose is to emulate the PS2's hardware, using a combination of MIPS CPU Interpreters, Recompilers and a Virtual Machine which manages hardware states and PS2 system memory. This allows you to play PS2 games on your phone, PC, or gaming handheld, with many additional features and benefits.
Thank You
The ARMSX2 team is eternally indebted to the PCSX2 project it is based on. We are so fortunate to build on their 20 years of hardcore development.
About This Fork
The upstream PCSX2 project ships an ARM64 interpreter build for ARM, but its high-performance JIT recompilers (EE, IOP, VU0, VU1, and vtlb fast memory) are x86-64 only.
This fork exists to close that gap. The goal is to preserve the correctness features of 20 years of PCSX2 development, while generating the fastest native ARM performance possible.
Current status:
- ✅ EE (Emotion Engine) recompiler — integer, float, MMI, COP0/COP1/COP2, branches, load/store
- ✅ IOP (I/O Processor / R3000A) recompiler — full integer, load/store, branches, coprocessors
- ✅ VU (Vector Unit) recompiler — microVU skeleton + Upper FMAC vector ISA complete; Lower ISA and runtime complete
- ✅ vtlb fast memory
- ✅ Native ARM64 binary builds and boots the PS2 BIOS
- ✅ 2D games are already playable
- ✅ 3D games run
Why LLMs / AI Were Used
A word on methodology:
The x86-64 JIT code in upstream ARMSX2 is already proven correct — it has run thousands of PS2 titles for years. The challenge in this port is not emulator design or JIT theory; it is mechanical translation of a large, well-understood x86-64 assembly codebase into equivalent ARM64 assembly (via VIXL) while preserving the exact same register-allocation contracts, block lifecycle, and recompiler semantics.
Large language models (LLMs) were used as an accelerant for this translation work — pattern-matching x86 JIT boilerplate to ARM64 equivalents, scaffolding emit routines, and keeping the porting velocity high. The JIT logic (block compiler, dispatcher, analysis passes, flag pipelines, clamping rules, Tri-Ace hacks, etc.) is taken directly from the upstream x86 implementation and validated against it. Nothing was hallucinated from scratch.
In other words: the hard engineering was done by the PCSX2 team over two decades. The hard typing — translating ~50k lines of x86 emitter code into ARM64 — is what AI helped compress.
System Requirements
ARMSX2 targets ARM64 across desktop (macOS, Windows, Linux) and mobile (Android, iOS/iPadOS), all from the single shared core. Our setup documentation page contains additional details on software and hardware requirements.
Please note that a BIOS dump from a legitimately-owned PS2 console is required to use the emulator. For more information, visit this page.
Building
Check out our github actions for the latest build recipe