Under the Surface of Classic Sonic

All about programming, unused content, and more in the Classic Sonic games!

[Under the Surface of Classic Sonic @SCDDeconstruct]

@Mellon_Nova Thanks for the reminder. Looking into this.

[Under the Surface of Classic Sonic @SCDDeconstruct]

A breakdown of the differences in the peelout and spindash between the original and 2011 remake.

[Under the Surface of Classic Sonic @SCDDeconstruct]

The 2013 remake of Sonic 2 directly ported the Death Egg Robot from the original game, but broke the way its arms launched at Sonic.

[Under the Surface of Classic Sonic @SCDDeconstruct]

Unreferenced demo data exists for special stage 2 in the v0.51 prototype of Sonic CD. It never gets decompressed into the demo data buffer nor does the code to run it get called. However, with some hacking, it can be restored.

[Under the Surface of Classic Sonic @SCDDeconstruct]

So, the 2013 remake of Sonic 2 made a change to the way the claw attack's hitbox works.

[Under the Surface of Classic Sonic @SCDDeconstruct]

If you're wondering why Hydrocity uses the Sonic 1 method... turns out the devs seemed to intend on HCZ using the gradual method. However, when I enabled the gradual method, the game ran fine for a bit, but then it suddenly froze. Will be investigating more.

[Under the Surface of Classic Sonic @SCDDeconstruct]

A technical dive (😉) into Sonic 3's water palette swapping!

[Under the Surface of Classic Sonic @SCDDeconstruct]

@wallslop Yup. There's even an example of this at the very end of the video.

[Under the Surface of Classic Sonic @SCDDeconstruct]

@krikzz Works perfectly now. Thank you!!

[Under the Surface of Classic Sonic @SCDDeconstruct]

@krikzz Can't seem to DM you, and this is my only remaining active account on this website.

A while ago, I sent a test ROM illustrating a bug with the Mega Everdrive Pro on the 32X, where ROM bank 2 reads wrong data. So, I updated the firmware today and ran the ROM again...

[Under the Surface of Classic Sonic @SCDDeconstruct]

@krikzz The point of the RV flag is to temporarily remove cartridge access from the 32X (SH-2 can't even access it when it's set) so that it doesn't get in the way, but if it hides the registers regardless, then yeah I see the problem.

[Under the Surface of Classic Sonic @SCDDeconstruct]

@krikzz I did notice that the in-game menu on the MEDpro doesn't work with the 32X. Maybe it would work if you utilize the RV flag?

[Under the Surface of Classic Sonic @SCDDeconstruct]

@krikzz From what I can understand, when the 32X is enabled and running, it takes priority over cartridge access, which I think is why it gets moved into its memory space. Some parts of the MD and MCD hardware aren't able to cope with this, hence why the RV flag exists.

[Under the Surface of Classic Sonic @SCDDeconstruct]

@krikzz The 32X does that, because ROM is moved into the 32X memory space, which cannot hold all 4 MB. So, it has to be split into banks. Adding the SSF2 mapper means dealing with 2 layers of bank switching, which, like I said, I am not doing.

[Under the Surface of Classic Sonic @SCDDeconstruct]

@krikzz I'm not using the SSF2 mapper at all. I'm using the standard 32X ROM bank switching, which splits the regular 4 MB ROM space into 1 MB banks.

[Under the Surface of Classic Sonic @SCDDeconstruct]

@krikzz Alright, so what's the plan, then? Is there something that I should be doing in my code that would prevent this scenario, or do you plan on figuring out how to fix it?

[Under the Surface of Classic Sonic @SCDDeconstruct]

@krikzz The same problem happens on The Mega Everdrive Core, by the way.

[Under the Surface of Classic Sonic @SCDDeconstruct]

@krikzz Now, my question is: did I miss a hardware revision to the cartridge itself that fixed it, or have there only been firmware revisions?