Simple Gens Tracer (2.12aR2) Usage for GG codes. Expert Level Thinking Required

[ugetab]

I'm taking a "Do it yourself" approach to hacking for now....

So, if you want any new Genesis codes, "Do it yourself". The tool to help you has appeared. There's more than enough brain-power out there funding adventures in Genesis hacking.

This mini-text is just to show the basics of how to setup the hooks so that the addresses modifying them will be possible to decypher.


Simple Gens Tracer (2.12aR2) Game Genie Code Hacking example:

Required: a PAR code in the format FF???? of the address modified.
Gens Tracer Genesis Emulator: http://www.romhacking.net/utils/337/

Wily's Tower:

Modified address: FFA1B6
FFA1B6 is the address that determines how many different games are on the screen. By logging the screen from before it loads to after it loads, the code that initializes the address can be found, and a log of the same event can be searched for coding that relates to the addresses you find. You can also check a disassembly of the ROM for exact info if needed.

1. Include hook: hook_wr* 0 ffa1b6 ffa1b6 (* = 1, 2, or 3)
2. Press "," on the main menu, before the game select screen.
3. Load the game selection screen.
4. Press "," to turn off logging
5. Close the emulator
6. Open hook.txt

It'll show this line somewhere in the file if you did it right:
[01:18A8] W16 = 0003 [FFA1B6]

[01:18A8] refers to the instruction after the one that performed the write, minus 2. The preceeding instruction is 6 bytes long (3 sets of 2 bytes). You should add 2 to this address, and check a "/" logged "trace.log" of the event so you'll get correct program code to search for. In this case, "01:18AA" is what to search for. Then, check the instruction preceeding it for the line responsible for the change.

In the end, the instruction
000118A4 357C 0003 005C MOVE.W #$0003,$005C(A2)
becomes
000118A4 357C 0004 005C MOVE.W #$0004,$005C(A2)

The code is:
0118A6:0004 (GG: ATNA-CAFG)

Converting Genesis .SMD Files into .BIN files:
Use GenRomSuite 2.8.2:
http://mipagina.cantv.net/tomman/genSuite/gs_en.htm
(This can also be helpful for the Decompiler)

.BIN Format ROM Decompiler:
http://www.classicgaming.com/epr/genesis.htm
Download sega-asm.zip

[MathUser]

Hey, neat. it's about time someone made one. I imagine it could make Tony Hedstroms job a bit easier. I will try it out too.

Edit:

I tried the file there and when extracting it I kept getting "error : file is not a vild archive". I wonder what is going on there, naturally the folder extracted was empty.

[Amy]

heh that 'edit' was funny

~Amy

[LiquidManZero]

Try redownloading the file when that sort of thing happens. Most of the time when I've had such a problem, it was an incomplete file from the downloading.

[ugetab]

Open the file with this program:
http://www.filzip.com/en/download.html

It's an ACE compressed file that ends with .RAR instead, making it hard to determine the correct program to use. Check the file in a text editor, and it should hint it's actual file type on the first line with "**ACE**", as well as noting that it was compressed using an unregistered version of an ACE compressor. It may have been intentional, so that you'd have to be mentally ready to make use of the hook lines it uses.

You need to exit the emulator, and start it back up each time you save new hook lines to the hook_log.txt file.

[Tony Hedstrom]

Good find ugetab. I gave it a quick try with "Spot Goes to Hollywood" looking for an infinite energy Game Genie code. The RAM address for energy was FFE30A. I added this hook: hook_wr1 0 ffe30a ffe30a, started the game, started the memory log, got hit, stopped the memory log. I opened the hook.txt file and saw: [2C:59E8] W16 = 00E7 [FFE30A]. Since I have some experience reading raw assembly, I was able to skip the instruction logging (trace.log) and use a hex editor to go straight to the ROM address given (2C:59E8) and figure out the Game Genie code (2C59E6:6002 = AKNW-2A9G). A real time saver! Thanks.

Tony.

P.S. I was playing around with the instruction logging (trace.log), and found that it is very useful for things like making high jump codes, etc. I love new toys. :-)

[MathUser]

Super jump codes are my favs. Good to see Genesis getting some more powerful tools. Perhaps we might wanna host a non ace'd version on the site. We don't want something like that to fade into oblivioun should something ever happen to romhacking.net

[LiquidManZero]

It's interesting... The newer versions of winrar will extract that file no problem, even though it's a renamed ace archive. Even though I doubt romhacking.net will disapear without a trace, I've uploaded a zipped copy of it here. Check the downloads page for the link...