MiSTer FPGA Forum

I'm having a bit of trouble getting Knuckles in Sonic 2 to run on my Mister FPGA. Tried grabbing the ROM from different spots, but every time it loads up, it's just stuck on a black screen. Any of you wizards out there got a fix for this? Would really appreciate the help!

If regular Sonic 2 is working it is likely to be the ROM.

• Could you provide the hash of your ROM?

• Which core are you using, the old "Genesis" core or the new "Megadrive" core?

• Do you have SDRAM? If so; have you tested it?

The regular Sonic 2 game works normally, and I've tested it on both cores. I have the 128MB SD RAM, and I've already run the test. Everything is okay.

It's strange that when using it on the PC emulator, the ROM works.

I know it's a very specific game, so I believe it might be related to lock-on technology. I'll research if any specific patch or dump is needed for this game to work.

If you could provide the hash of your ROM that would be super helpful, we could try to replicate the problem then.

Try changing the region setting too in case it is a timing issue and your region detection is doing something wonky.

Just checked and I'm seeing the same behaviour, black screen.

Sonic & Knuckles + Sonic The Hedgehog 2 (World).md
MD5: 3e5e4b18d035775b916a06f2b3dc5031

No issues with Sonic & Knuckles + Sonic The Hedgehog 3. Sonic 2 also fine. I could have sworn it worked previously.

[Edit]

After a bit of a Google I found a Portuguese streamer playing "Knuckles in Sonic 2" only a couple of days ago. I scrubbed through his footage to find he was using a ROM named 'Sonic_and_Knuckles__Sonic_2_W_f1.bin'. "f1" usually denotes a 'fixed ROM', sure enough I tracked down a fixed version of the ROM and it boots and plays just fine. The Sonic & Knuckles cart is ingeniously simple; when you connect it to Sonic 2 adds both ROMs, the Sonic 2 and Sonic & Knuckles patch ROM into the Megadrive's addressable memory space. When the console boots it's meant to execute code almost exclusively from the patch ROM in the top-most half of memory, the notable exception being the sound driver. So yeah, likely intended (or expected) behaviour without a patched ROM.

Black screen for me with Alien 3 and Xenocrisis too. I need to reboot the Mister because it gets stuck otherwise.

Alien 3 (f9e32be60028206b3716f64f2ba0ab00) and Xeno Crisis (50cca5273cdb6d6df36cbd29dbd3ff7f) work absolutely fine for me.

There's a working Sonic 2 & Knuckles rom with a md5 hash of bdd13934f4f31bf4d849ef8597d4a07c. I checked it against the rom listed in No-Intro's database (Sonic & Knuckles + Sonic The Hedgehog 2 (World) (Rev A) (Lock-on Combination)) with a hex editor and it differs in exactly 4 bytes.