New here! also seeking advice.

[Pisces]

Hi! I love psx games, and recently began daydreaming of all the things possible with rom hacking.
however i have pretty much ZERO experience with any of it.

I wish to make a code for destruction derby 1 and 2 on psx to play as the cpu's cars.
How would i go about this? or if anyone is wise enough with roms, hacking and codebreaker, could you possibly make this dream come true for me?

[Jorpho]

The Definitive Guide to ROM Hacking for Complete Beginners

See also other associated links under "Getting Started" over to the left there.

[FaustWolf]

Hmm, do any PSX emulators have built-in value search/comparison utilities? E.g., like ZSNES and SNES9x? Depending on how this game handles the data you're looking for, it might very well be an easy code to create; the problem will be finding tools that are friendly to the task.

Provided a proper tool exists, what I would do here is a process like the following:

*Choose a less advanced/starting car.
*Choose a car you expect is more advanced. Check RAM for values that have increased.
*Get back in your less advanced car. Check the previous results for values that have sinced decreased.
*Get back in your more advanced car. Weed the results again.
*Rinse and repeat until you've winnowed out your target RAM address or a small handful of possibilities. Once you've found the address the game writes car indices to, you can try changing it until you're sitting in an enemy car.

That's how I'd go about it in an SNES emulator at least. I'm not sure if there's considerations that come into play in PSX memory addressing I'm missing, other than possible lack of user-friendly cheat searching. It might even be the case that your game doesn't use high level indices for this function, so it could get way messier than what I describe above.

Anyway, this is a great way to get into modifying games, because you'll learn some useful things about RAM addressing along the way. Pretty soon after that you can get into debugging and tracing!

[Pisces]

I know it's possible since someone found a way to on youtube
http://www.youtube.com/watch?v=WYSn9xxN-5M

unfortunatly he hasnt been online since so hasnt been able to reply to me as to how he did this.
I'm trying to make the exact same code, and also for this games 1st edition, destruction derby 1.

EDIT: also, faust, I downloaded a hex editor since im not sure if the psx emulator i chose had it's own.. uhhhvalue searcher.

[Jorpho]

A hex editor and a value searcher aren't the same thing.  A value searcher actually looks at what's in the system's RAM while the game is running – and indeed, if such a thing exists for PSX emulators, it will make what you're proposing much easier.  (Since we've established that it's apparently been done by someone else already, it's probably not all that difficult to do.)

[Pisces]

Can you recommend a good value searcher for psx? or do I just need to whip out google.

EDIT: Googling "psx rom value searcher" has bared no results...

[Jorpho]

Searching for values has very little to do with the ROM , or disc image in this case.  It is something that, for practical purposes, can only been done in an emulator while the game is running.

Googling for <psx value search> turns up http://www.kh-vids.net/archive/index.php/t-44673.html as the second hit.

[Pisces]

Thank you ever so much Jorpho, I'll get to grips with this pec thing right away, seems like it will be the lifesaver of this whole operation.
However, I just tried to start the epsxe.exe to find "this application has failed to start because zlib1.dll was not found, re-installing may fix this problem"
what exactly is zlib1.dll?

[Jorpho]

http://www.lmgtfy.com/?q=zlib1.dll

[Pisces]

xD thanks again, I found it in the meantime after realising how dumb that Q was.
got one of my roms running, made a button config and am about to try out the value search in a sec, so far so good!

EDIT: one thing i've noticed with both the roms i got is that the in game songs are not playing, i mean there is still sounds like car engines, menu buttons and whatnot, but the games actual soundtrack seems to be gone, how do i go about resolving that? Not too peeved by it though, it's just a little thing i noticed. My main concern is still how to read values and to learn how to implement changes I make to the values.

[Jorpho]

Get an original copy of the game instead of downloading it.    The game apparently uses CD audio for music, which may have been overlooked by whoever made the rips you are trying to use.

P.S. Stop calling them ROMs.  They are not ROMs. 

[KingMike]

If you downloaded it, perhaps it is a "rip" (I think they're called) meaning somebody hacked out the music to greatly reduce the ISO size (possibly to save bandwidth). Second the "buy an original" option.

[Auryn]

It is a while that i didn't play destruction derby especially not on PSX so sorry if I am wrong.
There are some cars model that are used by the AI but can't be selected??
One of the first try I would make with PEC (or a gameshark/exploder if you have the hardware) would be to check the car selection screen and then put a value greater or lower as the min/max of the selections screen.
Example put the cursor (selection) on car 1 and start a search, then search same value, move to the 2nd car, search changed value till you get the address of the cursor position. Then suppose the max value you get from the select screen is 6, try put 7.

About how to apply your changes...there are basically 4 ways (3 have to do with pec and one is not):
-you generate a / many codes that will overwrite the car selection so it doesn't matter witch car you select, you will play with an AI car. (need pec to be always running).
-you modify a savegame to have that car (if you lucky, if you do the version above and save, you maybe get this one or you need to make it manually).
-you expand the car selection with the new AI cars (indeep hacking with asm).
-you graphically just exchange the look of a / any car to AI (iso hacking).

[Pisces]

I DO actually have the ps1 discs of both of these games, will that be of any help?

[Auryn]

only if you have the real hardware and a cheat device hardware capable of search codes.



But what you have to do is the same.

What you have to choose as first, is if you just want to look like an AI car or have it specs too.

I would take a look: http://www.google.ch/#hl=en&xhr=t&q=destruction+derby+2+mods&cp=23&pf=p&sclient=psy&biw=1024&bih=632&source=hp&aq=0v&aqi=&aql=&oq=destruction+derby+2+mod&pbx=1&bav=on.2,or.r_gc.r_pw.&fp=830a70f838b6cfd7

For the soundtrack, check the audio settings.
Alternativelly, you can put the cd in a normal cd player and play from track 2 up (doesn't work on all cd player).

[Jorpho]

I DO actually have the ps1 discs of both of these games, will that be of any help?

I don't know what emulator you're using, but can't it use original discs inserted into your computer's CD-ROM drive?

Otherwise, it is fairly trivial to make your own complete images of your original discs using ImgBurn or any similar tool.

[Auryn]

Yes, emu can load the original discs but normally an image is faster.

By the way...for the serie "the apple doesn't fall far away from the tree" and investing 5 min more with google. i would try to contact this guy:
http://forum.driver-dimension.com/viewtopic.php?id=767

[Pisces]

I have the carmageddon mod that shows up on google too.

But I'm more interested in trying to access the CPU cars in the true games.
and the Disc question was only about the music, sorry if that part was confusing.

I'm not sure how the guy on youtube opened the cars but since i saw no cpu driving the standard player car, my guess is he found out a way to make a car modifier as you said.
Just not too sure where to start looking for values like, but it must revolve around those 3 cars... or not, I really don't know.

EDIT: Ahhh Bebo!! that's the guy that made this code 1st. He is credited in the youtube video, if only there was a sure fire way of contacting him, i shall register in case I can.

[Auryn]

That Driver mod can be found in various forums, google them and see where he is more present or where you find the newest post. Ask on the forum if somebody has his contact could help too.

[Pisces]

How do I bring up the value searcher with PEC? everytime I search a value it says too many to list, and with specific searches it shows no results.

EDIT: Found out how to value hunt using cheat engine (downloaded that instead)
I found the value for the car changing
009C5770 2 (0 = rookie car, 1 = middle car, 2 = pro car, so the 2 in that code meant i was using the pro, the value also changed to that when watching the demo of the cpu's car)
and a second address was found:
009D63D0 2 (this one doesnt change and is always on 2 when i look to see if it changed)

I'm not sure how to find the value of the cpu cars, also i cant add those address lines into PEC as cheat codes for my game, says 00 is not a valid cheat code or something.
Anyone who how I can convert it so i can start toying with it's values in game?