Hacking No$GBA assembling instructions?

[TwoSpikedHands]

Hello all, hope everyone is well

I had a few questions about NO$GBA's debugging functionality. I have learned quite a bit over the past few months trying to mod Tales of Phantasia GBA, including what most of the instructions do and how to trace them around and figure out what does what. I tried today assembling my own instructions into the ROM, and it worked! I was able to make an instruction that heals you after every battle.

Unfortunately, this did not save when i closed out of NO$GBA and reloaded the ROM, which i was expecting it to.

Some of the culprits I was thinking of was:

• NO$GBA's assembler just doesn't work like that and the session isn't really saved to the file
• The part that I was assembling in was in RAM, not in ROM (If it was in ROM, wouldn't it save for the future instead of being like RAM where it is volatile?)
  • The address that I was writing in was 0x8096F08

Any advice on this would be much appreciated!

 

[cearp]

I forget how NO$GBA works, but it wouldn't surprise me that it works that way (can't save modifications etc)
Better to just bring up a hex editor and make the modifications there.
I think BGB does let you do that from what I remember though

Or better yet, code the instructions and locations in a file and compile them, and patch the rom that way.
That way you can use version control, but importantly see your modifications clearly.
I'm not sure if there's a more recent/convenient way to do that, but I can take a look how I was doing it a few years ago if you'd like (method that I took from some other site)

 

[TwoSpikedHands]

I forget how NO$GBA works, but it wouldn't surprise me that it works that way (can't save modifications etc)
Better to just bring up a hex editor and make the modifications there.
I think BGB does let you do that from what I remember though

Or better yet, code the instructions and locations in a file and compile them, and patch the rom that way.
That way you can use version control, but importantly see your modifications clearly.
I'm not sure if there's a more recent/convenient way to do that, but I can take a look how I was doing it a few years ago if you'd like (method that I took from some other site)

That would be dope! I Understand how to change the instructions, but don't understand how to change the instructions in hex. if you maybe have a link to that it would be amazing!!

Post automatically merged: Feb 11, 2024

I forget how NO$GBA works, but it wouldn't surprise me that it works that way (can't save modifications etc)
Better to just bring up a hex editor and make the modifications there.
I think BGB does let you do that from what I remember though

Or better yet, code the instructions and locations in a file and compile them, and patch the rom that way.
That way you can use version control, but importantly see your modifications clearly.
I'm not sure if there's a more recent/convenient way to do that, but I can take a look how I was doing it a few years ago if you'd like (method that I took from some other site)

I checked out BGB as well, unfortunately it only emulates GB and GBC games

 

[cearp]

That would be dope! I Understand how to change the instructions, but don't understand how to change the instructions in hex. if you maybe have a link to that it would be amazing!!

It's a guide on how to make a hack for some megaman game, but it's the exact guide I used to learn a way to do what I mentioned above with a different gba game (using armips to compile asm and patching that to your rom).
So read through it carefully and it should be very helpful.
https://forums.therockmanexezone.com/intro-to-asm-modding-hooking-t5374.html

I checked out BGB as well, unfortunately it only emulates GB and GBC games

Correct, I should have made that clear!

Post automatically merged: Feb 11, 2024

And let us / me know how you get on

 

[TwoSpikedHands]

It's a guide on how to make a hack for some megaman game, but it's the exact guide I used to learn a way to do what I mentioned above with a different gba game (using armips to compile asm and patching that to your rom).
So read through it carefully and it should be very helpful.
https://forums.therockmanexezone.com/intro-to-asm-modding-hooking-t5374.html


Correct, I should have made that clear!

Post automatically merged: Feb 11, 2024

And let us / me know how you get on

This is AMAZING!!! thanks so much, i'll work on it today and see how it goes

 

[Jayro]

If you know the hex address, couldn't you just manually edit things in HxD?

 

[TwoSpikedHands]

If you know the hex address, couldn't you just manually edit things in HxD?

was thinking of doing that, but it seemed like a bit of a process to do so - until about 3-4 hours ago i didnt understand that hex can be translated into assembly lol

 

[TwoSpikedHands]

It's a guide on how to make a hack for some megaman game, but it's the exact guide I used to learn a way to do what I mentioned above with a different gba game (using armips to compile asm and patching that to your rom).
So read through it carefully and it should be very helpful.
https://forums.therockmanexezone.com/intro-to-asm-modding-hooking-t5374.html


Correct, I should have made that clear!

Post automatically merged: Feb 11, 2024

And let us / me know how you get on

Thank you SO MUCH for this guide.... The last time I attempted to mod this game was in 2017, and today was the very first time I have been able to get anything really concrete done. I just figured out how to load any text box into RAM into any NPC. I'm not quite to the point where I can change the stuff in ROM, but that is coming VERY soon.

Next time I post - fully custom textboxes for NPCs will be done

 

[cearp]

Great progress and very glad to hear it!
How I have found text in roms:

1. Go to some place where you can enter text (probably a name entry screen)
2. Find that in ram, by searching for changing values when you change the text (can try entering 0 then 1, or Y then Z, and searching for an increase of 1)
3. So you can type TESTING and you should see byte for T, byte for E, byte for S... etc
4. Take note of what bytes match text
5. Search the rom for text you know exists in the rom, using those bytes

It won't be as simple as that if the text is compressed, but I've been lucky enough that the games I've looked at have stored the text nicely