Jump to content
Sign in to follow this  
mumboking

Tutorial: N64 JAM Extracting

Recommended Posts

mumboking

I just discovered how to extract the JAM file from the N64 version of LEGO Racers.

 

Here's how I did it:

  1. Acquire LEGO Racers N64 rom. (You're on your own here.)
  2. Make a backup of the rom just in case you overwrite it by accident.
  3. Open the rom in a hex editor. I used HxD.
  4. If you don't see "LEGORacers" at the offset 0x20 (dec 32), use Tool64 to change the rom to Big Endian format.
  5. Search for the string "LJAM" and find the second result.
  6. Delete all data before the second "LJAM".
  7. Save the file as something like "N64LEGO.JAM".
  8. Extract the JAM file using a JAM extractor.

 

I'm not sure how much of the data on the end is unrelated, but the extractor completed successfully for me.

No, the N64 JAM cannot be used in place of the PC one. I have, however, used the circuit files from the N64 JAM on the PC version. Moving objects are glitchy though.

This method also works for extracting the JAM from Paperboy on the N64.

Share this post


Link to post
Share on other sites
JrMasterModelBuilder

Clever! The extraction will work perfectly because it only processes the header and extracts the files from their offset from the beginning of the file. Since nothing will reference anything beyond that, it will simply ignore the extra data.

Share this post


Link to post
Share on other sites
dead_name

Fascinating. I'll do this when I get home and run some difference-checking against the PC version.

Share this post


Link to post
Share on other sites
mumboking

I just tried modding the JAM and re-inserting it.

This is the method I used:

1. Modify the JAM files.

2. Rebuild the JAM.

3. Open the rom in a hex editor.

4. Search for the string "LJAM". It should be the second result.

5. Delete all data after and including the second "LJAM".

6. Paste the contents of the recompiled JAM at the end of the rom.

Notes:

Unsure if this messes up part of the game somewhere, as I don't know the offset for the end of the JAM in the rom.

It at least runs and can get into a race on Imperial GP.

It seems that the N64 version doesn't like 8 bit bitmaps, corrupted graphics appear instead.

24 bit bmps froze the game. Only tested once.

Modified SRF files do work.

Share this post


Link to post
Share on other sites
Jack Bluebeard

Hey guys, I've tryed with that method, but when I'm going to extract the JAM file my JAMExtractor gives me an empty folder. So, I've a question for you: the LJAM string is that after a string called "Error reading JAM file" offset 00001390 and 000013A0. Is that LJAM that you were saying? Or maybe is another string? Please answer me :wimp:

Share this post


Link to post
Share on other sites
Noob Slayer

You have to hit "find" 2 times. There's the first result, and then go to find and type in LJAM again for the 2nd result. That'll give you the correct string.

Share this post


Link to post
Share on other sites
Modded Lego

WOW! You guys found out how to extract the N64 version, Good Job! Rock Raiders United Is Really Rising to the occasion! Keep up the good work! :love:

Share this post


Link to post
Share on other sites
Noob Slayer

I'm really wondering how to do this for the PSX jam.
I loaded up a ROM into HxD and deleted all data before the LJAM string (strangely, there was only one LJAM string).
When I tried extracting it, the extractor couldn't do it.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.