Hacking PS1/2 Homebrew app GSHAX Tool: Create PSX GameShark Codes That Gain Code Execution Mid-Game

[alexfree]

https://alex-free.github.io/gshax-tool

GSHAX Tool is a portable open source program that can generate complete GSHAX codes from scratch. GSHAX Tool can output GSHAX codes to either a text file (.txt) or a real valid GameShark Lite save game file.

GSHAX codes are PSX GameShark codes that modify an existing function in a running game to instead execute custom MIPS assembly.

As an example of usefulness, GSHAX codes are used in Tonyhax International to load the Tonyhax International loader PS-EXE off of a memory card in slot 1, enabling the play of backup and import discs with a GameShark or other cheat device. This is very useful for the various PSX cheat devices that do not include a built in swap trick. Before you decide to create a GSHAX code, it is a good idea to see if your PSX cheat device includes a swap trick as that can be used much more conveniently to boot the Tonyhax International Boot CD in such a use case.

 

[SylverReZ]

https://alex-free.github.io/gshax-tool

GSHAX Tool is a portable open source program that can generate complete GSHAX codes from scratch. GSHAX Tool can output GSHAX codes to either a text file (.txt) or a real valid GameShark Lite save game file.

GSHAX codes are PSX GameShark codes that modify an existing function in a running game to instead execute custom MIPS assembly.

As an example of usefulness, GSHAX codes are used in Tonyhax International to load the Tonyhax International loader PS-EXE off of a memory card in slot 1, enabling the play of backup and import discs with a GameShark or other cheat device. This is very useful for the various PSX cheat devices that do not include a built in swap trick. Before you decide to create a GSHAX code, it is a good idea to see if your PSX cheat device includes a swap trick as that can be used much more conveniently to boot the Tonyhax International Boot CD in such a use case.

Really neat stuff <3

 

[alexfree]

v1.0.1 has been released, which includes a new 'Mode 1'. This allows a different exploit vector that enabled me to make a GSHAX code for my favorite game, Parasite Eve

https://github.com/alex-free/gshax-tool/blob/master/examples/parasite-eve-code.txt

 

[alexfree]

v2.0 has been released, which uses an entirely new more powerful method. This now works by rewriting a jump or jump and link instruction to go to a custom free RAM address which contains the stage 1 loader. This can now essentially work with any game (in theory).

I wrote a lot about how to make codes at the homepage: https://alex-free.github.io/gshax-tool .

https://alex-free.github.io/gshax-tool/#downloads

 

[alexfree]

v2.0.1 update:

• The MIPS assembly binary padding offset is now calculated automatically by the tool itself, which means GSHAX Tool now requires 7 arguments instead of 8.

 

[_47iscool]

Very nice.

I almost thought this was a GS code injector into the executable like the ones people made for PS2 and N64.

 

[alexfree]

Very nice.

I almost thought this was a GS code injector inot the executable like the ones people made for PS2 and N64.

You know, I thought about doing one for the PSX. Maybe I will now.

I did make a SM64 specific gameshark code injector before: https://alex-free.github.io/sm64gsw

 

[_47iscool]

You know, I thought about doing one for the PSX. Maybe I will now.

I did make a SM64 specific gameshark code injector before: https://alex-free.github.io/sm64gsw

I had no idea about this one. Nice!

I was referring to this: https://www.romhacking.net/utilities/1659/

 

[Jo_Ribeiro]

Muito legal.

Quase pensei que fosse um injetor de código GS no executável, como aqueles que as pessoas fizeram para PS2 e N64.

EI didn't know there was a tool for the N64

Post automatically merged: Thursday at 9:45 AM

Muito legal.

Quase pensei que fosse um injetor de código GS no executável, como aqueles que as pessoas fizeram para PS2 e N64.

EI didn't know there was a tool for the N64

 

[Jayro]

Would these be usable with a MiSTer setup? I don't think we can swap "discs" while keeping the simulated lid closed. As soon as we swap cue files, it reboots the core to that cue/bun and starts the bios.

 

[_47iscool]

@alexfree

Any news on a tool to convert the GS cart ROMs to PS-EXE's?

 

[alexfree]

Would these be usable with a MiSTer setup? I don't think we can swap "discs" while keeping the simulated lid closed. As soon as we swap cue files, it reboots the core to that cue/bun and starts the bios.

Guess not. How do you play fear effect or parasite eve like that? Those are just 2 examples of games that require a disc change normally in game play, with no option to save and then reset the console with i.e. disc 2?

Post automatically merged: Yesterday at 3:41 PM

@alexfree

Any news on a tool to convert the GS cart ROMs to PS-EXE's?

The executable could probably be extracted but I’m still not sure if it would work without the actual cart hardware. I’ll take a look when I have time.