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Excitebike saving/loading
http://forums.nesdev.com/viewtopic.php?f=3&t=9973
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Author:  NiceKen [ Mon Feb 20, 2017 2:23 pm ]
Post subject:  Re: Excitebike saving/loading

Hi there!

Sorry for upping this old topic, but I have registered here specially because of it.

I was looking for information about rom hacks of Excite Bike that could save tracks... without luck.

I know that Virtual Console version does, so I extracted that ROM to figure out if it was an emulator feature or a ROM modification.

It turned out it was a ROM modification, because in emulators the save / load feature works and this ROM creates an SRM file. Also, the ROM doubles the size of the original Excitebike one. The sad thing is it only saves one track, wasting a lot of the SRAM memory because each track I think it's only 256k.

Have anyone tried it before? Could it open the door for someone with some programming skills to hack it and put a selection menu where to choose from a number of slots which track to save / load?


Btw, sorry for my english, I'm spanish native :P

Author:  Drag [ Mon Feb 20, 2017 6:51 pm ]
Post subject:  Re: Excitebike saving/loading

I don't think anyone's made a rom hack to Excitebike to make the save/load work, but it doesn't seem like it'd be difficult to allow more than one track to be saved.

First, you'd need to figure out if the tracks are variable-sized or not. If the tracks are always the same size, it's easy; the next track is always XXX bytes after the current track. If they're variable sized, things get trickier, but not impossible. The easiest thing to do would be to determine what the biggest track size is, and then always leave that much space, and then you do the same thing as before; the next track is always XXX bytes after the current. You could fit more tracks into the save file if you only save the exact amount of bytes the track needs, but then things get complicated when you want to do certain things; like if you have 5 tracks and you want to delete track 3, or save over track 4.

After figuring out how to store the tracks in the save memory, you'd need to create a menu for selecting which slot to save to or load from, and you'd probably want to be able to give each track a name, or at least show which slots are empty and which ones have data. You'd also need to modify the existing menu so that SAVE and LOAD go to the new menu you just programmed.

Author:  NiceKen [ Tue Feb 21, 2017 2:21 am ]
Post subject:  Re: Excitebike saving/loading

Well, thanks for the answer.

Dooing a little more reserach, tt seems that somebody "did" a patch for SRAM before:

http://www.romhacking.net/hacks/2428/

That is a patch that converts the original ExciteBike ROM to the Virtual Console version. I don't know if the person who "made" that patch basically extracted the rom from the VC release and created an IPS file with the differences. It really seems so, because the ROMS are almost identical except for his "credits".

Anyway, I don't know at all how to do what you're saying. I know each track is 256Kb in memory, and the length of the track is basically specified with the Finish Line object. There is where it ends, but the memory used is 256Kb long in any case.

It would be really nice if someone is interested enough to build a version with a track selection menu :roll:

Author:  oRBIT2002 [ Fri Feb 24, 2017 12:57 pm ]
Post subject:  Re: Excitebike saving/loading

I did that patch. It's also available from my website at http://nes.goondocks.se/.
I didn't use some kind of Virtual Console ROM, it's just an ordinary Excitebike ROM-file. I patched the cassette-recorder stuff to write to SRAM instead.

Author:  NiceKen [ Mon Feb 27, 2017 11:02 pm ]
Post subject:  Re: Excitebike saving/loading

Oh, great patch then! I downloaded the VC game and extracted it's rom and it was almost identically, that's why I guessed that.

I suppose adding slots will be too much difficult...

Btw, I have seen great patches in your page. I want to try the arcade Duck Hunt on the NES, I always wanted to shoot the Dog! :D

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