Getting ROM address from RAM

[Shou]

Hi there, I like to play Mega Drive games on my Nintendo DS using an emulator, problem is the emulator in question (jEnesisDS) runs the games well, but has very little in the way of features not having a cheat code option. For games like Streets of Rage 1&2, you need a second controller to access the level select and harder difficulties which is not possible on this emulator.

Now it's simple enough to HEX edit game genie codes into a ROM, but PAR codes have RAM addresses so I've been trying to find the ROM address using this guide: http://thegshi.org/vb/threads/2317-N...Tracer?p=22740

The PAR code I've been trying to find the ROM address for is this one for Streets of Rage:

Enable Level Select and 7 Lives In Options FFFA7B:01

I ran a trace on the address using the hacked version of GENS as said in the guide and came back with these results:

[00:0FEA] W08 = 00 [FFFA7B]
[00:1172] W08 = 01 [FFFA7B]
[00:0FEA] W08 = 00 [FFFA7B]
[00:0FEA] W08 = 00 [FFFA7B]
[00:1172] W08 = 01 [FFFA7B]
[00:0FEA] W08 = 00 [FFFA7B]
[00:1172] W08 = 01 [FFFA7B]
[00:0FEA] W08 = 00 [FFFA7B]

TRACE STOPPED

I take it [00:1172] W08 = 01 [FFFA7B] is when the cheat is activated and 00:1172 is the address in the rom, so I did the search in the trace dump by searching for 00:1170 (subtracting 2), but I find nothing. I only find something when I search for 00:0FE8, but I don't know if this is the right address since the cheat is not active on that address.

Anyway I've tried all these address in the ROM and HEX'ed in values, but so far nothing works. I'm obviously doing something wrong here, but being new to this, I'm struggling to understand what I'm doing wrong.

If someone could please help me and point me in the right direction, that would be great, thanks!

[Hybrid]

enable level select and lives in options
A2JT-AR5N

00:116C 66 06 BNE #$06 [00:1174]

theres the guy you wanna change that 66 to a 67

[Shou]

Ah so I see, sometimes you need to add 2 instead of subtracting, or it just depends on the address type.

I made the change to the rom and it checked out ok in the Fusion emulator, but jEnesisDS nor WGENS emulators accept it, they just give a red screen on boot. I guess that can't be helped and it's just an emulator problem.

Thanks for the help, much appreciated and will take the new knowledge into consideration with future attempts.

[Tony H]

Hacking this code into the ROM should get rid of the red screen on boot...

$000348:6002

Only tested on SoR "REV01" version, not sure if it will work on REV00.

EDIT: You are getting the red screen because the checksum check failed.

[Shou]

Ya, that did the trick great thanks!

I figured it might be the checksum because in Fusion it always says "Checksum fixed" in the bottom right.