Rally Chase CD to Cartridge Conversion

Neo Alec

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Edit: tldr: Here are the four files to replace in your Thrash Rally rom set to convert it to Rally Chase:


And here's a .neo you can add to your set:

DarkSoft version:

ORIGINAL MESSAGE:

Has anyone ever tried to convert Rally Chase from the Neo Geo CD to cartridge? It's a single-load game with one PRG file. The CD version has a few differences: Some cars have manual shifting, I think it's easier. I kind of prefer Rally Chase. I thought it would be nice to be able to load the Rally Chase rom on the cart system.

Anyway, I tried to convert the RALLY.PRG to cartridge, but I can't get it to boot. Maybe it's because they've replaced all the music calls in the P rom on this game. Is there anyone better at this willing to take a look at it?
 
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Tarma

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It probably isn't thought highly enough of to warrant someone wanting to do such a conversion. Rally Chase / Cross is more than likely waaaaaay down on anyones list when thinking about Neo Geo games.

Shame, I quite like Rally Chase, it's quite fun to play. One of those games where screenshots never do it justice... because they make the game look like shit.

GIve me this over Over Top any day of the week. Now that game is trash.
 

Neo Alec

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It probably isn't thought highly enough of to warrant someone wanting to do such a conversion. Rally Chase / Cross is more than likely waaaaaay down on anyones list when thinking about Neo Geo games.

Shame, I quite like Rally Chase, it's quite fun to play. One of those games where screenshots never do it justice... because they make the game look like shit.

GIve me this over Over Top any day of the week. Now that game is trash.
Right. Well, I thought I could get it running pretty fast by byteswapping it and changing the header. Assuming they didn't change the program too much, it could be really easy, so it wouldn't matter how far down the list it is.
 

Tarma

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Right. Well, I thought I could get it running pretty fast by byteswapping it and changing the header. Assuming they didn't change the program too much, it could be really easy, so it wouldn't matter how far down the list it is.
So you going to give it a go?

Slightly unrelated - I saw Rally Chase offered for sale with the comms link cable the other day... did that thing ever even work???
 

kernow

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I'm sure there was a post here with 8 player league bowling on four machines 🤔
 

Neo Alec

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So you going to give it a go?

Slightly unrelated - I saw Rally Chase offered for sale with the comms link cable the other day... did that thing ever even work???
Yeah, I gave it a go already and failed, so I'm posting here. I will probably give it another look.

The link cable? Do you mean the AES version, Thrash Rally? Yeah, I've played the link mode. It was an AES linked to an MVS in fact.
 

Burning Fight!!

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Neo CD thrash rally ruelz.

@Neo Alec I admit I haven't done anything substantial on the Neo but what I'd do is boot up mame's debugger and set up a breakpoint at $320000 r/w (reg_sound) for that PRG you posted AND in the original MVS romzors. Should be the easiest way to figure out how to bring back the original Z80 command calls?
 
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Burning Fight!!

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Hey I want to post videos too.


As you can see, yeah it's easier on the CD version. There's really not much reason to choose any automatic car over the Porsche with its "turbo" gear.
 

Burning Fight!!

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now that's a screen I only ever see on the flyer :lolz:
having the extra race available on the title screen makes much more sense if you consider multi-link mode. hmm
 

Neo Alec

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Hey I want to post videos too.


As you can see, yeah it's easier on the CD version. There's really not much reason to choose any automatic car over the Porsche with its "turbo" gear.
I still need to get used to it. The manual controls are still wonky for me. How do you brake? Is there no need to break?
 

Neo Alec

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So basically I'm trying to run the CD to cart conversion instructions in reverse.

1. I tried to swap four bytes at address 0x64 and 0x68 of the program. 0x64 and 0x68 were both 00 so there wasn't anything to do.
2. I copied 0x40-0x63 from a byteswapped 038-p1.p1 (the Thrash Rally cart rom).
3. I byteswapped the whole file.

It boots to an error from the Unibios running in MAME. The Unibios does detect the game ID as 038, so at least some of the header is correct.
rallychase_error.png
 
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Burning Fight!!

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Well the jukebox works correctly because the Z80 is pretty much isolated from the 68000 with its own V ROM.

Send that rom of yours so we can take a look

I still need to get used to it. The manual controls are still wonky for me. How do you brake? Is there no need to break?
The most you will need in Thrash Rally/Rally Chase is to release the accelerator button a bit to make a curve. IMO the whole gameplay revolves around anticipating the curves to enter them as smoothly as possible without letting go of the accelerator.
 

Burning Fight!!

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Hey Alec, you didn't swap the IRQ1/IRQ2 vectors as I can see, the values are 4-byte addresses so you swap $64 with $68, $65 with $69, etc.

That should be a start. I'll test my copy asap.
EDIT: the title screen works and coin-up too, demo too (!!!!) but after starting the game it crashes. Hmm.

Music works but it hangs the game for a bit before continuing, maybe the game is waiting for a status update from the CD drive and giving up?
 
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kernow

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Do you people have any coding skills or are you just fucking around trying things because..

It's pretty impressive regardless
 

Neo Alec

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Do you people have any coding skills or are you just fucking around trying things because..

It's pretty impressive regardless
Fucking around. I have dabbled and studied what I could about Neo tech in my spare time.
 

Neo Alec

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Hey Alec, you didn't swap the IRQ1/IRQ2 vectors as I can see, the values are 4-byte addresses so you swap $64 with $68, $65 with $69, etc.
Thanks! This is exactly the kind of help I needed. I wasn't sure if I did that right. So do I need to do this before the byteswap?

I think it's hilarious that to build the title screen they just reused the word "Rally" and moved it up. By the way, why does everyone think they renamed this game for CD? I guess it was because someone at SNK was intent on updating the game slightly, and they renamed it to reflect the changes.

 
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wyo

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Maybe they realized "Thrash Rally" doesn't make any sense.
 

Burning Fight!!

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Thanks! This is exactly the kind of help I needed. I wasn't sure if I did that right. So do I need to do this before the byteswap?

I think it's hilarious that to build the title screen they just reused the word "Rally" and moved it up. By the way, why does everyone think they renamed this game for CD? I guess it was because someone at SNK was intent on updating the game slightly, and they renamed it to reflect the changes.

I vote for keeping the original C ROMs for that stupid title screen, if this ends up working out in the end. :D
Either swapping before or after the pairwise bitswap is fine, I just swapped them in the file you posted (too lazy to write something to swap bytes haha)
 

Neo Alec

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I vote for keeping the original C ROMs for that stupid title screen, if this ends up working out in the end. :D
Either swapping before or after the pairwise bitswap is fine, I just swapped them in the file you posted (too lazy to write something to swap bytes haha)
Yeah, it worked for me without byteswapping it back first. I use romwak from Jeff Kurtz. Just use the /f option.

It seems like it's hitting something in the PLAYER_START routine that doesn't work. I've been referring to freem's documentation here to try to get some insight:

The cart-to-CD conversion process is documented online, but there is no CD-to-cart that I'm aware of. There's probably something simple I'm just not accounting for. I'll bet folks who have written dev environment's like freem's that automatically output a NGCD version of the rom could find the problem pretty fast.

Music works but it hangs the game for a bit before continuing, maybe the game is waiting for a status update from the CD drive and giving up?
I wonder if they just built in a wait based on about how long it takes after boot for the CD drive to catch up and start playing the music. Otherwise maybe it's waiting for status from the CD drive (I'm not sure if the NGCD is that sophisticated though).

Edit: I think you're right actually, because if I try to start the game on the black screen it continues to wait for a while before the difficulty select comes up.

Maybe they realized "Thrash Rally" doesn't make any sense.
We should edit the title screen to say what I call it sometimes, "Trash Rally".
 
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