Sony Playstation 1 (PSX)

Edit on Github | Updated: 11th November 2019

Introduction to Hacking the Sony PlayStation

Welcome to our page dedicated to PS1 reverse engineering! The PlayStation 1, or simply the PS1, was a popular gaming console released by Sony in 1994, and it became a beloved classic of the gaming world. If you’re interested in learning more about the technical aspects of this console and how it works, you’ve come to the right place.

On this page, we’ve compiled a list of links to other pages that cover various topics related to PS1 reverse engineering. Whether you’re interested in understanding the hardware architecture of the console, analyzing game code, or exploring the many mods and hacks that have been created by enthusiasts over the years, you’ll find a wealth of resources and information on the pages we’ve linked to.

So grab your DualShock controller, and get ready to dive into the exciting world of PS1 reverse engineering!

Retail Playstation hardware

The PS1 was competing against both the Nintendo 64 and Sega Saturn during its lifetime and in some respects was the underdog in terms of processing power and graphics.

However don’t be disillusioned the PS1 was still a very powerful machine for its time and when programmed correctly games could look stunning, sometimes even better than the Nintendo 64!

PlayStation 1 Hardware Architecture

For more information on the PS1 hardware architecture check out this post.

The main parts of the hardware are:

32-bit MIPS CPU (33.96Mhz)
GPU - Unlike more modern GPUs it Only handled 2D Polygons (360k per second) ¹
Geometry Transformation Engine (GTE) - 1.5M Vertices per second ¹
24 Channel sound chip (SPU)

Geometry Transformation Engine (GTE)

The Geometry Transformation Engine or GTE was what allowed the Playstation to handle 3D graphics, it specifically designed to do the sort of fast mathematical calculations used for Vertex/Geometry processing. Without it the Playstation hardware would not have been able to pull of the excellent 3D graphics it was known for in its time.

Playstation 1 Geometry Transformation Engine (GTE)

To find out more about the the Geometry Transformation Engine check out this post.

One interesting limitation of the PS1 GPU is that it didn’t have a Z-buffer so polygons needed to be sorted by the PS1 CPU instead, so often the Painters algorithm was used ¹.

Unofficial Hardware Add-ons

Sony PlayStation VCD Player Add-On Card

The Youtuber Scarlet Sprites has a good overview of this rather rare unofficial Chinese PS1 add-on which allowed playing the rather obscure Video CD (VCD) format on retail Playstation 1 consoles:

It plugged into the back of the console via the IO and AV ports without any need for additional power and has a switch on the top to switch between VCD mode and game mode. This suggests that the playstation first boots into the IO port before running the game disc.

Also note that there was an official PS1 model released in Japan that played Video CDs called the SCPH-5903 VideoCD which has additional hardware inside the console.

Games

What would the Sony Playstation be without its excellent line-up of games? It was the games that attracted many people away from the Nintendo 64 and Sega Saturn and on to their very first Sony console.

Playstation 1 Games with Debug Symbols

An excellent way to start reverse engineering is to find games where the developers accidentally left the Debug symbols in the retail release of the game. While this is not very common it has happened for a few games released for the Playstation One and gives you access to all the original function and variables names that were used in the retail source code.

Playstation 1 Games with Debug Symbols

For a list of PS1 games that have debug symbols available check out this post.

Crash Bandicoot

Crash Bandicoot was one of the first 3d platformers that managed to deliver quality gameplay while looking impressive for its time.

It was created by Andy Gavin and Jason Rubin for release on the original Playstation console, and both developers have been kind enough to share ample amount of information on how the game was implemented.

Crash Bandicoot

To find out how Crash Bandicoot was developed check out this post.

Remastered PS1 Games

Some classic PS1 games have been remastered or remade for more modern consoles, if you are looking to reverse engineer one of these games it may help to look at the modern version to find additional information that may be relevant.

Name	Platform	Notes
Ape Escape	PSP	Source Code was ported to the PSP as Ape Escape: On the Loose
Crash Bandicoot 1-3	PS4, Switch, PC, XboxOne	Remade in Alchemy engine but tried to be as faithful as possible to the originals
Crash Team Racing	PS4, Switch, XboxOne	Remade in Alchemy Engine with additional content from Crash Nitro Kart and Crash Tag Team Racing
Castlevania SOTN	Xbox360, PS4, iOS, Android	Re-Released in Castlevania Requiem compilation
Final Fantasy 7-9	PS4, Switch
Legend of Mana	PS4, Switch, iOS, Android	Original engine but with higher resolution assets? (confirmation required)
MediEvil	PS4	Remade in the Unreal Engine
Mega Man X 4	PS4, Switch, XboxOne	Source Code Port of X4 Released in Mega Man X Legacy Collection
Metal Gear Solid	Gamecube	Remade for Gamecube as Metal Gear Solid: The Twin Snakes
PaRappa The Rapper	PSP, PS4	The PS4 version is actually just a the PSP version emulated with higher resolution assets
Resident Evil 1-3	PS3, PS4, XboxOne	Does this use original engine with higher resolution assets?
SaGa Frontier	PS4, Switch, iOS, Android, Windows
Spyro 1-3	PS4, Switch	Remade in Unreal Engine 4 but aims to be as faithful as possible to the originals
Tony Hawk’s Pro Skater 1+2	PS4/5, Switch, XboxOne	Remade in Unreal Engine 4

Wipeout Omega Collection is one game that did not make the list as its technically not a remaster of the PS1 original. This list also doesn’t include projects such as PS one Classics as they were just emulations of the original PS1 games running on a more modern console and not either a source port or a full remake.

Tool-Assisted-Speedruns (TAS) for PS1

In this video EZScape demonstrates a few speed runs for PS1 games that could never be possible by humans as they require changing the controller input every single frame. He shows techniques such as Zig-zagging in Crash Bandicoot, Pac-Man World and Spyro 3.

If you are interested in creating your own Tool-Assisted-Speedruns then you might want to check the latest version of BizHawk. If you are interested in improving some existing TAS then check out PS1 Tool-assisted movies - TASVideos

Development Kits (Hardware)

Development kits are released to game developers before the launch of the system to allow games to be developed for the system’s launch. These systems would evolve over the systems lifespan and contained useful features for debugging and optimizing games for the platform. These systems were not just limited to the official offerings by Sony as a few other publishers had their own versions of development hardware.

Official Development Kit

The official development kit for the PS1 was a partnership between Sony and SN Systems which allowed developers to use their PC to interact with the real PS1 hardware.

Official PlayStation 1 Development Kit (Hardware)

For more information on the official Sony Playstation Devkit check out this post.

Official Consumer Development Kit (Net Yaroze)

The official development kit for the PS1 was only available for licensed game developers but there was a stripped-down version available for the general public known as Net Yaroze.

Net Yaroze - The PS1 Consumer Dev Kit

For more information on the consumer development kit known as Net Yaroze check out this post.

Software Development Kits

Official Software development kit

The Official Software development kit was developed by a partnership between SN Systems who are known for excellent 3rd party development kits and the Game Studio Psygnosis who are known for excellent quality games.

It was initially called PSY-Q and even although it was owned by Sony it was actually a cross-platform development kit which included support for the Sega Saturn!

Sony later rebranded the SDK to SDevTC at some point in 1998(?).

Official Playstation 1 Software Development Kit (PSYQ)

For more information on Official SDK for the Playstation 1 check out this post.

Official 3D Graphics Tools (DTL-S220A)

In August 1998 Sony provided a CD to developers with a bunch of 3D Graphics tools² such as:

Meditor - Material Editor
BMP2TIM, PICT2TIM, RGB2TIM, TIMUTIL.EXE - Tools to convert image formats into the PS1 texture image format TIM

Also provided was the 3D Graphics Tools manual with tutorials on how to use the provided software.

PS1 File formats

Playstation 1 File Formats

For more information on PS1 File Formats check out this post.

PS1 Executable Format

The PS1-EXE (executable) format is detailed in the post below:

PSX-EXE Format

For more information on PS1 EXE File Format check out this post.

Game Asset Creation Tools

Ever wondered how your favourite game artists made assets for Playstation 1? Although the exact software used for most games are still a secret, we have managed to piece together what we know so far about how 3D models and 2D Images were created.

What software was used to create 3D models for PS1 games?

To create 3D models for Playstation 1 games the following tools are known to have been used:

trueSpace for PlayStation - Directly reads the PS1 RSD format rather than going through the standard DXF ²
3D Studio - Exports to DXF format
AutoCAD - Exports to DXF format but not really made for game development