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Author Topic: Phantasy Star 2 Rom Hacking  (Read 11042 times)

marlin1500

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Phantasy Star 2 Rom Hacking
« on: December 22, 2013, 08:01:38 am »
Hi I am looking for something similiar to the below for Phantasy Star 2, does anyone have any info on what offsets are used to control who can equip which piece of equipment in the game?  I am not talking about save state editing but using a hex editor to change the actual rom itself.
http://www.wrftpb.com/psiv/

tryphon

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Re: Phantasy Star 2 Rom Hacking
« Reply #1 on: December 22, 2013, 11:12:38 am »
You can find some PSII hacks here, maybe they documented it.

If you don't find what you're looking, I can do some research, but what do you want to do exactly ?

marlin1500

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Re: Phantasy Star 2 Rom Hacking
« Reply #2 on: December 23, 2013, 04:25:03 am »
Thanks I've looked into the packs, I managed to hack PS4 easily with the data and hacks but I don't know where to start with PS2, basically I want to make the weaker characters stronger by increasing their weapon and armour options.  For some characters can use a normal knife but not a laser knife or dagger, it doesn't make sense.

I also want to change the damage values to make say the bowgun useful early on so Rudo isn't always using a shotgun.

FAST6191

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Re: Phantasy Star 2 Rom Hacking
« Reply #3 on: December 23, 2013, 05:12:31 am »
Not exactly what you want but some game genie codes will probably get you closer to where you want to be

http://www.romhacking.net/forum/index.php/topic,16454.0.html I do not know how far the OP got (it would probably be able to do what you want) but there was nice stuff along the way.
http://www.phantasy-star.net/psii/psiicode.html
http://codehut.gshi.org/PStar2GG.txt

Alternatively the stuff from Tony H (the last link) has some stuff on changing item stats, availability in shops and costs....

marlin1500

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Re: Phantasy Star 2 Rom Hacking
« Reply #4 on: December 23, 2013, 05:40:55 am »
Thanks but how will the genie codes help? They do not change the rom so I can I compare an original rom to one run with a code?

FAST6191

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Re: Phantasy Star 2 Rom Hacking
« Reply #5 on: December 23, 2013, 06:08:13 am »
I did not check at length but game genie codes do change the ROM -- you can quite easily hardpatch them or decode them.
http://gamehacking.org/wiki/Hacking_Genesis

If you want a hardpatch program then CCCGP from http://crackerscrap.com/index.php (click on projects).

(Pro) Action replay, codebreaker, GameShark... those typically fiddle with RAM but most game genie stuff is ROM patching code.

marlin1500

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Re: Phantasy Star 2 Rom Hacking
« Reply #6 on: December 23, 2013, 07:22:59 am »
Thanks I found the offset for bowgun damage bu when I make a change to it the rom will not load in gens and just has a blank screen, from memory is this something to do with the checksum? If so which algorithm do I use?

December 23, 2013, 07:43:49 am - (Auto Merged - Double Posts are not allowed before 7 days.)
Yes its the checksum error as I thought, how do you change it the FixCheckSum.exe does not correct it.
« Last Edit: December 23, 2013, 07:43:49 am by marlin1500 »

Tony H

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Re: Phantasy Star 2 Rom Hacking
« Reply #7 on: December 23, 2013, 09:20:18 am »
Using the master code will kill the checksum check.  You can find the master code here:

http://www.angelfire.com/games2/codehut/PStar2GG.txt

or here:

http://codehut.gshi.org/PStar2GG.txt
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marlin1500

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Re: Phantasy Star 2 Rom Hacking
« Reply #8 on: December 23, 2013, 08:40:36 pm »
Thanks, I can't seem to get the weapon damage codes to work though, the code to make the shotgun one handed worked fine, but not weapon damage ones.  If anyone has a list of offest's I would be very much appreciative.

December 24, 2013, 01:31:48 am - (Auto Merged - Double Posts are not allowed before 7 days.)
Right from Numan Revolution Hacked Rom
                     Column    00 01 02 03 04                                         05  06  07  08    09  0A                                             0B - 0F
 Sonic Gun 00013C20   ?    ?   ?   ?   1st Letter in weapon Name  3rd 5th 7th 9th  ?    A3=2 Handed / A2=1 Handed.  ??????

No idea where the even numbered letters are or anything else, the Shotgun is offset 00013C30 and is the same.  Anyone got any ideas?
« Last Edit: December 24, 2013, 01:31:48 am by marlin1500 »

Chippy2000

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Re: Phantasy Star 2 Rom Hacking
« Reply #9 on: December 24, 2013, 02:22:53 pm »
Maybe the guns you mentioned are the same? Beta element discovered?

Thanks, I can't seem to get the weapon damage codes to work though, the code to make the shotgun one handed worked fine, but not weapon damage ones.  If anyone has a list of offest's I would be very much appreciative.

December 24, 2013, 01:31:48 am - (Auto Merged - Double Posts are not allowed before 7 days.)
Right from Numan Revolution Hacked Rom
                     Column    00 01 02 03 04                                         05  06  07  08    09  0A                                             0B - 0F
 Sonic Gun 00013C20   ?    ?   ?   ?   1st Letter in weapon Name  3rd 5th 7th 9th  ?    A3=2 Handed / A2=1 Handed.  ??????

No idea where the even numbered letters are or anything else, the Shotgun is offset 00013C30 and is the same.  Anyone got any ideas?
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marlin1500

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Re: Phantasy Star 2 Rom Hacking
« Reply #10 on: December 24, 2013, 03:49:24 pm »
I've made a great deal more progress and found where the even numbers of weapons are found and the offset to change who can wield what, for example the stock hex numbers are FD for the knife & for 44 for the shotgun.  What  confuses me is that the attack value which is the next offest after one or 2 handed has no effect on the damage a weapon does.  This seems really bizarre unless the attack value is used when calculated a hit or miss.

Actually for melee weapons the attack value should calculate damage.
« Last Edit: December 24, 2013, 03:57:45 pm by marlin1500 »

Chippy2000

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Re: Phantasy Star 2 Rom Hacking
« Reply #11 on: December 24, 2013, 04:03:02 pm »
Maybe it DOES calculate a hit or miss. Why not Google it? Maybe an answer will surface from the depths of the INTERNETZ.
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Tony H

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Re: Phantasy Star 2 Rom Hacking
« Reply #12 on: December 24, 2013, 07:50:23 pm »
Don't forget that there are 2 different versions of that ROM.  There is a regular version, and a "REV A" version.  I'm pretty sure I used the regular version to make all of the codes. 
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marlin1500

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Re: Phantasy Star 2 Rom Hacking
« Reply #13 on: December 26, 2013, 03:51:30 am »
Thanks, the master code got rid of the checksum.  Found some more weapon data 2 handed guns double the hex attack value in game, I've found where weapon defence is as well, I still have no idea where the data for gun damage and multiple targets is.  I also have no idea what the offset immediately before 1/2 hands & users does they seem to be a whole bunch of random numbers that have no effect in game.

The 2 offsets above affect the price in shops of items, the offset value before attack value increases the price by 256 & the offset before users increases the price by 1.  The attack value for 2 handed melee weapons is also doubled in game from the hex value, unlike guns this directly affects damage, double the hex value and the weapon damage is doubled.
« Last Edit: December 27, 2013, 07:12:48 am by marlin1500 »

Chippy2000

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Re: Phantasy Star 2 Rom Hacking
« Reply #14 on: December 27, 2013, 04:41:23 pm »
Well, google answers everything, and sure enough, you were all right.
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marlin1500

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Re: Phantasy Star 2 Rom Hacking
« Reply #15 on: December 28, 2013, 02:50:42 am »
No google involved this is all through my testing, I found the techniques now.

Does anyone know of a hexeditor that will allow me to search for and replace hex values within a given range? Every one I have found will only allow you to search/replace - up/down/all.  If I can replace the damage value for a gun as it is a know value ie. 0a for the shotgun I can narrow the search down until I find it. 
« Last Edit: December 28, 2013, 08:22:40 am by marlin1500 »

Chippy2000

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Re: Phantasy Star 2 Rom Hacking
« Reply #16 on: December 28, 2013, 11:02:47 am »
Maybe looking through the coding will help a little via looking for hexadecimals and all that jazz. Hex editors? Can't help you there since i don't use hex editors for ANYTHING. I prefer doing the 'ol switcheroo.
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Tony H

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Re: Phantasy Star 2 Rom Hacking
« Reply #17 on: December 28, 2013, 07:31:41 pm »
Thanks, I can't seem to get the weapon damage codes to work though, the code to make the shotgun one handed worked fine, but not weapon damage ones.

Are you talking about the "Attack" codes? If I recall, those codes change the "Attack" stat (and some change the "Defense" stat as well).  Is there another stat for Damage?

December 28, 2013, 09:06:50 pm - (Auto Merged - Double Posts are not allowed before 7 days.)
I think I found the problem. If you enter one of the codes that makes your weapon stronger (higher "Attack" value) at the start of a new game, you will see the new, higher Attack value from the very beginning. If you enter one of the stronger weapon codes from a saved game (save state), the new "Attack" value may not show up until you enter battle. If you unequip the weapon, and then re-equip it, the new higher Attack value will show up immediately.

I entered my code that makes the Knife 10x stronger from a save state. My stats showed that I had 17 ATK (which is the normal amount you have when starting a new game). I went into battle and did massive damage with the knife (47 to 54 damage to the enemy).  Without the code, I did 6 damage to the enemies.

December 28, 2013, 09:10:16 pm - (Auto Merged - Double Posts are not allowed before 7 days.)
Forgot to mention... If I unequipped the knife and then re-equipped it, my ATK stat went from 17 to 62.
« Last Edit: December 28, 2013, 09:16:21 pm by Tony H »
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marlin1500

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Re: Phantasy Star 2 Rom Hacking
« Reply #18 on: December 29, 2013, 03:19:10 am »
Yes thats what happens with melee weapons, guns have a different mechanic which I'm trying to work out where it belongs, see below a link to a page that has some damage formula's.  Its done the bottom.
http://www.rpgdl.com/forums/index.php?topic=224.0

Tony H

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Re: Phantasy Star 2 Rom Hacking
« Reply #19 on: December 29, 2013, 11:37:47 am »
Give me some time to buy a bow gun, go into battle and make an asm trace log to find out where the stats are located in the ROM.
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