A couple of 6502 hacking questions

[BeyondTheStatic]

Hi,

I'm totally new to ASM hacking, so please bear with me.

What I'm currently trying to do is make some codes for Simon's Quest where the whip can break any block. Using the power of the nail as a starting point, I wish to find the mask through which all blocks can be considered breakable or not. I've narrowed down an address that trips a breakpoint whenever a breakable block is being destroyed. This is at D619. I'm using FCEUXD.

It breaks right after an RTS, which means I've probably found a subroutine. Unfortunately, I can't seem to find what called it. How do you locate the code that called a particular address? There's no find option, and I can't select everything so I can find all the references in another program. If I could propagate my search up through the code, I might be able to track it down...

My second question pertains to bullet/item collisions with the landscape. How do you find a routine that trips when a bullet/object collides with the landscape? It happens so quickly that there seems to be no change of catching it in the cheat search.

~BTS

edit: Oh yeah, a third question. I was following the SMB3 ASM Hacking by DarkHackerBoy, and was wondering if the alterations could be converted to Game Genie codes or not. I'd like to reduce most modifications to at least six GG codes, so they could be played on real hardware. THX

[nolberto82]

You will have to look back in the ASM. You can make a trace log to see what the game is doing. There must a CMP that compares to see if you are hitting a breakable or non-breakable block.

[BeyondTheStatic]

I was looking for a CMP, or even and AND, but found nothing in the debugger. I'll definitely try out your suggestion. Thanks~

[BeyondTheStatic]

Just following up...

How do you find a routine that trips when a bullet/object collides with the landscape?

The trace logger in conjunction with the code/data logger helps immensely here. Activating the code/data logger and letting the game to run through everything unique before allowing a bullet to make contact has been working out quite well.

I was following the SMB3 ASM Hacking by DarkHackerBoy, and was wondering if the alterations could be converted to Game Genie codes or not.

After reading some of the tutorials again, I knew it had to be possible. As it turns out, it's the same procedure, but you make GG codes at the NES memory offsets in question instead of directly editing the hex fields at the ROM offsets.

Hopefully I can now go beyond simple codes, to try some things I've had in mind

~BTS

[Helder]

It's always nice to hear people achieve new heights just from learning how the asm functions and learning to manipulate it.