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PSeudo JS

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What PSeudo JS is

PSeudo JS is a JavaScript emulator for PlayStation (PSX) that runs on the web and can load some commercial games. Its code combines .h headers and .js files, then inlines modular code before runtime; it is compatible with ES5 JavaScript and later. Building it requires the Clang compiler and a terminal build command. To run the project, users need a localhost server such as Apache, and testing requires a valid BIOS file in the bios folder. The maker does not provide information about where to find a BIOS file. Development progress is listed for several components: CPU Mips R3000A at 95%, DMA at 90%, CD Decoder at 75%, Audio at 60%, and XA Audio at 10%. The maker describes the speed and overall experience as mediocre and says timing is inaccurate. The CPU uses a slow interpreter, with a JavaScript tracer intended to improve speed planned for later. PSeudo JS is free and open source under the Apache 2.0 license.

Who it suits

It may suit developers or technically minded users interested in a JavaScript PSX emulator who can build and serve a web project locally. Users need to provide a valid BIOS file themselves.

What it does well

  • Free and open source under Apache 2.0.
  • Can load some commercial games.
  • Compatible with ES5 JavaScript and later.
  • Uses WebAudio and WebGL.

What to know first

  • Requires Clang to build.
  • Must run from a localhost server.
  • A valid BIOS file is required.
  • The maker reports inaccurate timing and slow performance.

Limits

The maker describes speed and the overall experience as mediocre at best, with quite inaccurate timing. The CPU currently relies on a slow interpreter; a JavaScript tracer is planned for later.

Getting started

  1. Open the project website at https://naden.co/pseudo.
  2. Build the project with Clang by running the repository’s build command in a terminal.
  3. Run it from a localhost server such as Apache.
  4. Place a valid BIOS file in the bios folder for testing.

Verdict

PSeudo JS offers an open-source web emulator project, but its own description notes performance and timing limitations. Building, local hosting, and providing a BIOS file are prerequisites.

Questions

Is PSeudo JS free?

Yes. It is free and open source under the Apache 2.0 license.

Which platform does it support?

The listed platform is web.

Does it require a BIOS file?

Yes. Testing requires a valid BIOS file in the bios folder.

Can it run commercial games?

It can load some commercial games.

Who makes PSeudo JS?

The maker’s site identifies Nadenco Smpc and lists Athens, Greece as its location.

Facts from PSeudo JS's own pages

BIOS sourcing
The maker says they will not provide information on where to find a BIOS file. · github.com, 9 Oct 2026
Browser technologies
The project repository tags it with WebAudio and WebGL. · github.com, 4 Oct 2026
Build requirement
Building PSeudo JS uses the Clang compiler and the project’s build command in a terminal. · github.com, 9 Oct 2026
Codebase
It uses .h headers alongside .js files, inlines modular code for optimization before runtime, and is compatible with ES5 JavaScript onwards. · github.com, 4 Oct 2026
Code structure
The project uses .h headers alongside .js files, inlining modular code for optimization before runtime on the VM. · github.com, 9 Oct 2026
CPU implementation
The project uses a slow CPU interpreter, with an attempt to speed it up using a JavaScript tracer planned later. · github.com, 4 Oct 2026
Game support
The emulator can load some commercial games. · github.com, 9 Oct 2026
JavaScript compatibility
The codebase is compatible with ES5 JavaScript and later. · github.com, 9 Oct 2026
License
PSeudo JS is open source under the Apache 2.0 license. · github.com, 9 Oct 2026
Live build
The maker’s site links to a live build at https://naden.co/pseudo. · github.com, 9 Oct 2026
Maker
The maker’s site identifies the company as Nadenco Smpc and gives Athens, Greece as its location. · naden.co, 9 Oct 2026
Performance limit
The maker describes the speed and overall experience as mediocre at best and says the emulator is quite inaccurate on timing. · github.com, 9 Oct 2026
Performance limitation
The maker describes speed and overall experience as mediocre at best and timing as quite inaccurate. · github.com, 4 Oct 2026
Progress
The repository lists CPU Mips R3000A at 95%, DMA at 90%, CD Decoder at 75%, Audio at 60%, and XA Audio at 10%. · github.com, 4 Oct 2026
Purpose
PSeudo JS is a PlayStation (PSX) emulator written in JavaScript. · github.com, 9 Oct 2026
Run requirement
The project must run from a localhost server such as Apache, and testing requires a valid BIOS file in the bios folder. · github.com, 9 Oct 2026
What it does
PSeudo JS is a PlayStation (PSX) emulator based on JavaScript. · github.com, 4 Oct 2026

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