Open-source PlayStation 1 research

PSXRecompStudio

Open-source PS1 binary analysis, MIPS R3000A validation, and static recompilation research.

Works today: Bounded recompilation and interpreter comparison, plus PS-X EXE/CHD analysis.

Not yet: Complete commercial-title AOT recompilation or playable native ports.

Start here: Read the FAQ, try the CLI, or pick a first contribution.

01 / Mission

Preserve the possibility of a native port.

Develop open, reviewable tools for authorized PlayStation game research, preservation and eventual re-releases. A reusable, maintainable recompilation foundation matters more than claiming early compatibility.

01 / RESEARCH

Open engineering

PS1 binary analysis, MIPS semantics and an independently reviewable recompiler/runtime.

02 / EVIDENCE

Measured progress

Separate synthetic validation, real-title interpreter observations and native execution claims.

03 / COMMUNITY

Small contributions welcome

Reproductions, focused tests, design challenges and documentation are first-class contributions.

02 / Progress · snapshot 2026-10-20

What the evidence actually shows.

Source baseline: main@551f50ab. This is a dated summary, not a live CI or compatibility counter. Draft PRs are not counted as landed work.

OBSERVED / INTERPRETER

Persona opening imagery

ATLUS logo and opening Japanese text rendered with OpenBIOS. Real-title visual evidence is interpreter-only.

VERIFIED / SYNTHETIC

Runnable native slice

Five-instruction PS-X EXE recompiles and runs with the alpha CLI. Not whole-game support.

INVESTIGATING / STANDALONE

Fallback, throughput, display

Timed-out standalone runs, loaded-code mismatches and unverified visual parity are tracked in #768, #773, #774 and #806.

NOT REACHED / V0.1 GATE

Persona title screen

No confirmed title-screen or playable commercial-title native port. Milestone #351 remains open.

Detailed, scope-limited evidence: Persona E2E log · Capability matrix · Open issues

Technical collaborators welcome

Japanese-language Issues and technical discussions are welcome. 日本語の参加ガイド

We welcome independent, critical human reviews. Specialists in PS1 BIOS and hardware, MIPS I, static recompilation, runtime integration, testing, and game preservation can contribute through a focused question, architecture review, or reproducible synthetic test—not only through large code changes.

Transparent AI use: the maintainer defines the direction, but AI coding agents are heavily used for coding, investigations, tests, documentation, and preliminary review. Automated CI is important bounded evidence, not a substitute for independent engineering review.

Current limits: Persona opening imagery comes from the OpenBIOS interpreter path. Title-screen progress, full commercial-game native AOT parity, and playable native ports remain unverified. Our proposed multi-platform plugin ecosystem is a long-term concept, not a shipped feature.

How to get involved Future RetroRecompStudio vision · Contributor guide

Latest milestone: OpenBIOS interpreter reaches Persona opening imagery

The OpenBIOS interpreter path now visibly reaches the opening of Megami Ibunroku Persona. VBlank-accurate captures show the ATLUS logo and narrative text referencing Zhuangzi's butterfly dream.

ATLUS logo — VBlank 1200

Japanese opening narrative text about the butterfly dream — Opening narrative — VBlank 2700

Scope: Verified game-rendered progression, not complete-title AOT recompilation, title-screen access, or playable compatibility. See capture evidence and implementation in PR #754. Imagery is limited interoperability research evidence; rights remain with their owners and this project is not ATLUS-affiliated. See the legal and asset policy for rights and contact guidance.

What is PSXRecompStudio?

PSXRecompStudio is an open-source research toolkit for analyzing original PlayStation software and validating static recompilation techniques. It combines PS-X EXE and supported CHD analysis, MIPS R3000A execution models, deterministic recompiler validation, runnable generated-host artifacts, and partial PS1 Runtime hardware models.

It is a research platform, not a claim of complete commercial-game compatibility. The current project can prove bounded real-ROM-derived recompilation paths and classified execution outcomes, but it does not yet turn complete commercial PS1 titles into finished native ports.

What works today

R3000A / MIPS I instruction modeling, decoding, memory behavior, delay-slot behavior, exceptions, interrupts, and deterministic Golden Trace validation.
Disc-analysis flow covering CHD input, ISO 9660 structures, PS-X EXE extraction, MIPS analysis, basic blocks, and control-flow graph extraction.
A synthetic MIPS recompiler vertical slice plus bounded real-ROM-derived function proofs, whole-corpus coverage reporting, deterministic host C generation, and differential validation against the interpreter.
Runnable generated-host artifacts and a headless psxrecomp recompile / psxrecomp run CLI with classified JSON results and privacy-safe diagnostic bundles.
Partial Runtime hardware support including BIOS HLE, production-reachable interrupt/timer/DMA/memory/SIO0/SPU register state, and a managed GPU model with minimal rasterization and deterministic frame snapshots.
Compiler-enforced architecture boundaries and a stable C ABI shared by the C# layer and the mixed C++/Rust native core.

Not yet implemented

End-to-end recompilation of complete commercial PlayStation 1 titles.
A finished runtime for native PS1 game ports.
Complete GPU, SPU, CD-ROM, MDEC, and GTE support.

Technology stack

C# and .NET

Domain logic, analysis, validation, tests, and managed interop code.

Avalonia

Cross-platform desktop application shell and future analysis workflows.

C++, Rust, and CMake

Native CPU, memory, and hardware-oriented components coexist behind a stable C ABI while semantics migrate incrementally to Rust.

C ABI and P/Invoke

A narrow managed/native boundary keeps C++ and Rust implementation details out of C#.

Explore the project

Choose a starting point below to explore the research, tools, and contribution opportunities.

START HERE Frequently asked questions What works, what is still experimental, and how to begin. TOOLS Command-line guide Try analysis and bounded recompilation from the CLI. RUNTIME PS1 runtime status Explore the hardware models and current execution limits. ENGINEERING Architecture See how analysis, recompilation, and native code fit together. PROGRESS Research roadmap Follow verified milestones and the remaining challenges. VISION RetroRecompStudio vision Read the long-term, multi-platform research direction. COMMUNITY Get involved Find a focused way to contribute evidence, code, or review. SOURCE GitHub repository Browse source code, discussions, issues, and contributions.