LotusDec 20, 2022
Sebastian Staacks

Finally released: The GB Interceptor.

An open source rp2040-based adapter that goes between your (unmodified) Game Boy and the game cartridge to record or stream your gameplay via USB.

Video: https://youtu.be/6mOJtrFnawk
Details: https://there.oughta.be/a/game-boy-capture-cartridge

A Game Boy capture cartridge: The GB Interceptor

YouTube
Dec 20, 2022 at 4:10pmWeb
Show threadhalcy​ Dec 20, 2022
@DiConX @razor big fan of how i think anyones first thought would be „wait, how does that even work, they can‘t possibly just have an emulator in lockstep“ and actually that is exactly what’s happening
Show threadFrost「｜｜霜の狼｜人面獣心」🐺❄️Dec 20, 2022
@halcy @DiConX @razor oh NEAT!
Show threadFabian WahlsterDec 20, 2022
@halcy @DiConX jup very satisfying to see that this really works so well 🙂
Show threadSebastian StaacksDec 20, 2022
@halcy @razor
Damn, I wish I had thought of the term "lockstep" when describing how it works...
Show threadDaniel M KarlssonDec 20, 2022
@DiConX Haaawt!
Show threadDavid AmadorDec 20, 2022
@DiConX this is so cool, thanks for making it
Show threadPapaErnie69Dec 20, 2022
@DiConX Very very cool ! 🥰
Show threadcolinhay3sDec 20, 2022
@DiConX very cool
Show threadPunnO)))Dec 20, 2022
@DiConX This is awesome!
Show threadReilly GrantDec 20, 2022
@DiConX I need to jump on the "I can't believe this actually works" bandwagon. Very well done.
Show threadAlex AkersDec 20, 2022
@DiConX This is great! @NeoNacho sent me your post!
Show threadHernan VanegasDec 20, 2022
@DiConX it's a pleasure to simply watch this things, really...
Show thread🌪 MikeMathia 📡Dec 20, 2022

@DiConX

That is pretty sweet.

Good work.

Show thread@itsmistermoon Dec 20, 2022
@DiConX that’s just beautiful!
Show threadNick MuldoonDec 20, 2022
@DiConX amazing!
Show threadflutterby 🦋Dec 20, 2022
@DiConX this is a wonderful and fun idea! so glad to have something like this for the GB folks out there looking for modless solutions!!
Show threadBilliard LentilDec 20, 2022
@cobracommander ^^^ !!!
Show threadCommander SupremeDec 20, 2022
@BilliardLentil i am going to stream making chiptunes and games 24/7 now.
Show threadKitlithDec 20, 2022

@DiConX very nice!

If the rp2040 was setup as a MITM instead of a passive sniffer, you might be able to read out the DIV register by spoofing some instructions before returning to the normal game code? but that probably also violates the idea of "running unmodified code."

Could the link cable issue for 2 player tetris in theory be solved by also sniffing the link cable? (barring performance constraints, which you're already having issues with)

Show threadSebastian StaacksDec 21, 2022

@kitlith
Yes, it was important to me that the cartridge is still directly connected to the Game Boy, but code injection might be another very rewarding project.

I think that sniffing the link cable would not be that bad in terms of performance as the link cable is very slow and the rp2040 can just capture everything with a PIO and put it in a FIFO, so the CPU would just pick up the data when it would virtually read that register. But on the hardware side it would be quite a contraption.

Show threadEllieDec 21, 2022
@DiConX This is absolutely ridiculous. I love it.
Show threadaddieDec 21, 2022
@DiConX This is incredible. Need it now
Show threadSapphic LawyerDec 22, 2022
@DiConX now can you make one for the Sega Game Gear?
Show threadSebastian StaacksDec 22, 2022
@SapphicLawyer No idea, never had a Game Gear and don't know much about it. Since I am already at the limit of the rp2040 the slightly better specs of the GG might require a faster micro processor (or FPGA). Whether the principle works here also depends on how much the Game Gear reveals on the memory bus. For example, it is very useful that the Game Boy sets the address pins of the cartridge to the current program counter even when it is executing code from RAM.
Show threadDaniel CollinDec 22, 2022
@DiConX Very cool! Great work :)
Show threadjigbeanDec 24, 2022
@DiConX Filed under things I didn't know I wanted until someone invented it. 👏👏👏
Show threadHumbird0 FandomJan 13, 2023
@DiConX
I'm very curious about how this works on a technical level. I wouldn't expect the gameboy to be sending its screen frame-buffer to the cartridge or vice-versa. How is video output data available to the cartridge pins?
Show threadSebastian StaacksJan 14, 2023
@humbird0 Since the Game Boy runs its code directly from the cartridge, the Interceptor can follow the same instructions and recreate the VRAM content. A emulated graphic unit then renders the image. (The links in the post provide much more detailed explanations.)
Show threadHumbird0 FandomJan 14, 2023
@DiConX
Parallel emulation?!
That's freakin' nuts! Of course that would be possible now.