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User Info: MeteorStrike

MeteorStrike
11 years ago#1
Hi everybody. It has been a while since I last posted about the Game Genie debug mode code. I made some time to finish this off, at least to the extent that I planned to work on it. Here is a quick recap and stuff about this:

What is it?

A while back, a Game Genie code to unlock Debug Mode for this game was discovered. Check out the topic titled "Balloon bug and outright cheating" for more information on this.

Basically, the game will check the address at $C000 to check its ( constant ) value in order to make some decisions on what happens. For example, if $C000 has its 4th bit cleared, the game will let you select which chapter to start on when you create a new game! Since this address always has a constant value, only a Game Genie code can change it, and hence, a Game Genie code that clears bit 4 will enable this option, which is obviously intended for debug purposes only. ( Hence, it is a Debug Mode option enabled through a Game Genie Code )

Cool, what's the code?

Not so fast. Unfortunately, a little bit of an explanation is needed, because things are not as simple as we all wish they were, and without this explanation, you'll likely won't like the Debug code too much...

There are 20 possible known places where the game checks $C000 to make decisions, hence having 20 programmatic effects. Some of these effects, unfortunately, are undesirable, so a Game Genie code must be carefully selected so that only the bits we want to set and clear are done so. Here is the breakdown of the 20 addresses:

Effect Number, Bits needed to change, Effect

1 = 0x08 = Chapter selection enabled
2 + 3 = 0x80 = Press B to walk thru walls in locations
4 + 5 = 0x80 = Press B to walk thru walls on world map
6 + 7 = 0x40 = No random battles, press and hold Start to re-enable them
8 = 0x10 = Return has multiple locations enabled
9 - 16 = ALL = Slot machines behavioral changes
17 = ALL = Casino monster Colosseum / Battles ???
18 = ALL = Casino monster Colosseum / Battles ???
19 = 0x40 = Casino monster Colosseum / Battles ???
20 = 0x20 = Boss battles ???

The first 16 effects are fully known and desirable. Effects 17 and 18 are simply unknown and therefore are potentially problematic, OR completely harmless. It is best to avoid them unless and until they are fully understood ( which may be never ) Effect 19 is bad and will crash the game, and finally, effect 20 is probably good, but still unknown, so who knows...

All bits start as set, so to enable a Debug Mode, we want to CLEAR the required bit(s). As you can see from above, the No random battles debug effect requires that we clear bit 0x40, but the harmful effect that freezes the game is also enabled when bit 0x40 is cleared. As a result, we cannot make a single Game Genie code that will clear this bit without worrying about the bad side effect that it will cause due to the other effect that this bit controls. :(

We can get around this kind of problem by making additional Game Genie codes, but this is beyond what we want to do right now. For starters, we need to completely understand what the unknown effects really do, ( which will probably never happen seeing as how no one is really interested enough to continue this work ) and then we can make the best possible codes for the effects we want.

User Info: MeteorStrike

MeteorStrike
11 years ago#2
In the meantime, we can make some DEBUG MODE candidate codes for the effects we want:

DEBUG MODE GAME GENIE CODE 1: SAFEST
Enable as many effects as possible that are desirable, but do not enable any of the bad effects or unknown effects. Basically, we need to keep 0x40 and 0x20 ON so that we do not suffer their effects. Doing so will also prevent the other 2 unknown effects from happening. This version will therefore be the safest. However, since we will keep those 2 bits on, we also loose the No random battles effect, as well as the slot machines effects.
C000 ? FF : 60 = ATEGAENY

DEBUG MODE GAME GENIE CODE 2: COMPLETE
Enable all Debug Mode effects. This will result in the game crashing when you get into certain battles, including the Colosseum. As long as you don't get into ANY battles, this version should be completely safe.
C000 ? FF : 00 = AAEGAENY

Why would the game crash due to a debug effect?

Although there is no real way of knowing the answer to this, my personal theory is that this debug option was meant to enable some sort of battle editor, or something of the sort. This probably took a lot of additional resources, and so the entire thing was probably scrapped. When the debug code tries to enable such a mode, it essentially calls into a piece of code that doesn't exist, because it was removed altogether, thereby causing a crash.

Note that this is 100% a theory and there is NO WAY of knowing if there is absolutely any truth behind this at all! Please do not spread this as a rumor of any sort! We all hate that! This is simply a theoretical possibility of how a debug mode would cause the game to crash. Nonetheless, there is likely no way to ever know why the game crashes for sure, but the point is, it does, so we need to avoid that debug option in our final and ultimate debug code.

Enabling bit 0x40 can crash the game if I get into a random battle, but it also disables random battles, so why is it unsafe to use?

Good point, but remember, if you press and hold start, you can get into random battles again, and then suffer the side effect. Also, the effect happens on boss battles as well as Colosseum fights, so you need to be sure to avoid all battles if you try the complete debug code...

What are the slot machines' changes that take place with the debug code?

They are relatively minor.

1 - There is a message that is displayed or not displayed when you start to play.
2 - You can stop the reels by pressing the A button.
3 - Reels can spin for a longer amount of time before they stop on their own.
4, 5, 6, 7 - The reels decelerate smoother.
8 - When a round is over, pressing and holding a button won't prevent the next round from starting.

For the most part, they are automated-testing-friendly effects, not really anything you would care about... much...

User Info: MeteorStrike

MeteorStrike
11 years ago#3
How can I help figuring out the last 4 unknown effects?

I made some Game Genie codes that would enable ONLY those 4 effects that are currently unknown. Here they are:

// 17 - Casino monster Colosseum / Battles ???
AEXZXLLA

// 18 - Casino monster Colosseum / Battles ???
AEUEIPGI

// 19 - Casino monster Colosseum / Battles ???
AAVUEYIG

// 20 - Boss battles ???
SZEZGXSE

You may need to enable all 3 of 17, 18 and 19 to witness the game-freezing effect. For the most part, figuring out 17 and 18 would be nice, but they appear to be related to the game-crashing effect, number 19. It appears they all deal with the same issue although only one of them actually leads to a crash. I doubt their effects will ever be known because I predict that whatever they are supposed to do, it is something that was removed from the final build of the game completely...

The 20th effect seems legit, although I don't know what it does. Address $6E44, bit 0x40 is always set before a boss battle, but this debug effect skips the setting of this bit... it would be nice to know what this is supposed to do...

So, that's pretty much it. I'm pretty much done researching the debug code. The only thing missing is those 4 unknown addresses, so anyone that wants to figure out what they do ( at least the last one ) and report back, that would be great. Enjoy! :)

User Info: Lolo_Guru

Lolo_Guru
11 years ago#4
Wow. Nice codes here. I'm going to break out my cartridge and game genie and give these a try.
Petition v3: To allow interactive stories on boards w/o corresponding social board:
http://boards.gamefaqs.com/gfaqs/genmessage.php?board=7&topic=44148055

User Info: Lolo_Guru

Lolo_Guru
11 years ago#5
[This message was deleted at the request of the original poster]
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