Tripping the Lock-On™ Technology

I don't know, the GTA London was a separate disc and didn't rely on the original. It was most definitely the same engine and concept in a hastily-developed relase though, much like how a different studio years later reskinned Guitar Hero II to make Guitar Hero: Rocks the 80s. Calling these DLC doesn't feel right, but they're also rather clearly "same as an existing game but with some tweaks."

 

Lords of Chaos had an expansion pack in 1990. (And yes, you needed to own the original game to run it.) But technically that's also a computer game, not a console game.

 

Here's a cracker, 1985 Revs for the bbc micro had Revs 4 Tracks. A genuine addon that needed the original game to play! I miss the 90s style pc expansion pack in its own separate full sized box. Much better than it all being parcelled up and sold as tiny little separate things.

Never heard of any console games doing that though.

 

This conversation should probably be moved to another thread.

 

It already is!

 

Ooh Wizardry 2 is a great answer. Anyway, back to Sonic & Knuckles :-) Not fully understanding how s&k works, does this mean that theoretically any game can access s&k assets via lockon?

 

Yes, but the point is that the code jumps from Sonic & Knuckles into the cartridge ROM, so you can effectively make your own "& Knuckles" mode.

 

I've been on the verge a few times of questioning whether this was possible, but I wasn't sure if you'd have to hack up a Sonic & Knuckles cart as well as a separate game, which would defeat the purpose.

I would very much like to see a "Disney's Aladdin & Knuckles", which was (I think?) the first game we tried back in the day to see if it would work. Make my dreams come true~


But I suppose the community ought to start small. "Sonic Eraser & Knuckles" must be doable. Granted, Sonic Eraser was never put on a cartridge, but it's simple and tiny and replacing crappy Sonic sprites with crappy Knuckles ones could be done without an artist.

 

The Kosinski trick works, because of the way Sonic 3 & Knuckles loads the Sega logo. The graphics for it are compressed in Kosinski format, and it gets decompressed into the beginning of work RAM from the Sonic 3 before being transferred into VRAM. With that, you can setup a fake Sonic 3 header and place a set of Kosinski data where it would normally see the compressed Sega logo graphics, and basically clear out most of RAM, and then overwrite the return address for that specific Kos_Decomp call. From there, it'll return to the address you specified.

 

At this point, it sounds like a reverse Lock-On, with the attached game using the Sonic & Knuckles cart for data instead of the other way around.

 

"Reverse" lock-on is basically the way KiS2 works, on the scale of the memory chip.

I like this idea. Why not "Street Fighter II & Knuckles" ?
Easily doable is "Knuckles in Sonic 1". And why not "Sonic & Knuckles & Knuckles" ?

 

I had a dream when I was a kid, of this.
It eventually shown up in the real world as Sonic Classic Heroes, but in my dream it was Carnival Night, so S3K heroes.
Incidentally, it was the first thing I tried when I was a teen with 2 of S&K were in my possession. I should have known what to expect =P

“& Knuckles” totally became a meme at one point. I wouldn’t be surprised if it became a hack trend to lock-on to games never previously intended. I hope so, it’ll be an amusing wave of creativity!

 

For best title I raise you

"Metal Fangs & Knuckles"


Although "Sonic Crackers & Knuckles" is a fair second place. Sounds like cereal mascots.

 

On a more serious note, I am not able to make the lock-on work with a Mega Everdrive X7. Is there a way to make Mega Everdrive work like an MDPro?

 

I don't think so, because all Sonic & Knuckles will see is the Everdrive's boot ROM.

 

I'm curious to know the extent of compatibility for the KtEiS2 exploit route so I'm releasing this debug build of Gatoslip for anyone willing to give it a shot.

https://cdn.discordapp.com/attachme...362f8b0c828a4790d5d97e78022f1d40ff0a4b1704d9&
(apologies for the Discord file link, there appears to be a filesize limit on the forum)

Spoiler: Known Issues

- Collision routine hasn't been modified yet, so the flutter dodge move doesn't work as expected
- Super sprites use placeholders
- No Special Stage sprites yet
- Casino Bonus Stage spawns a dummied object and softlocks the game, avoid orange stars
- Many of the sprites don't exist for the S&K part so they'll either play a weird animation or be T-posing
- S&K loves having its objects call the DPLC routine directly, so if the player sprites turn to a glitchy Sonic, that'd be why
- If the player angle isn't near 0 and S&K decides to do the above, the game will crash, this has to do with how the extra angles are handled and doesn't have anything to do with the exploit.

I expected SRAM to be an issue but wasn't aware mirroring could be a problem depending on the hardware, a shame since this is quite an elegant solution.


- Alone it should just play the Christmas SAGE demo of Gatoslip, bare some oddities due to the hitbox viewer.
- When attached to S&K it should display it's own message, send you to blue spheres and after exiting that, send you to S&K where Extended Edition Pantufa becomes playable (very WIP)

Compatability list (thanks to RedHotSonic for testing these):
FlashkitMD - Works Flawlessly
EverDriveMD3 - Plays a unique Bluespheres stage since the first 2MiB are occupied by the Everdrive boot ROM, so it read the Gatoslip Header
DragonDrive - Plays S&K normally (in fact, it doesn't work with S1 either)

Debug mode is turned on, Super sprites are stored in the 3MiB section so if it displays garble instead of the placeholders, that would be why.

For the sake of compatability with future SRAM cartridges, I'll switch to the S3 RAMsplosion method.

 

This reminds me of my favorite quirk of the S&K cart: the reason carts larger than 2MB don't work, and why Sonic Classics/Compilation gives you the full Blue Sphere, is because when the MD accesses addresses from $200000+, the S&K cart simply forwards the request to the locked-on cart slot (except when the UPMEM chip gets involved), leaving the highest bit of the address intact. So if the cart has data at/beyond $200000, it ends up reading the data at that location in the locked-on cart, which incidentally in Classics/Compilation happens to be the location of the S1 ROM header. Emulators obviously won't replicate this memory mapping, which is why you can get Blue Sphere levels from 4MB ROMs in emulators.
Of course, this all requires having dedicated carts for your ROM, so I don't know how useful it is for anything.

 

Yeah, I figured expansion packs and the like were a thing from the moment hard drives and software that took up multiple floppies were a thing... and even on the console side, there were things like Satellaview and I believe the Famicom Disk system had kiosks that could put extra content onto rewritable disk, though I assume most, if not all of the Satellaview and FDS content(possible exception for any FDS games that got an NES cart release) had a harder time surviving, if any have been preserved...

More on topic... I really don't know many Genesis games outside of Sonic, but Ristar and Knuckles might be cool... Or something crazy like someone porting SNES platformers to Genesis just so they can have the and Knuckles treatment... Donkey Kong COuntry 3 and Knuckles anyone?