RAM watching on a real NES?

Discuss hardware-related topics, such as development cartridges, CopyNES, PowerPak, EPROMs, or whatever.

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slembcke
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Re: RAM watching on a real NES?

Post by slembcke »

I think NESpectre is related. A guy from my IGDA chapter worked on it: https://www.youtube.com/watch?v=FSj9rw70Ppk

They said they had a NES where they put "dual port RAM" in it, hooked it up to a microcontroller, and connected to that over a serial port.
LittleRain
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Re: RAM watching on a real NES?

Post by LittleRain »

Ahh very interesting. Thanks for the link!
Ive been trying to contact Trey on twitter to ask him how its done with no avail. I guess it still isnt 100%, but seems likely.
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infiniteneslives
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Re: RAM watching on a real NES?

Post by infiniteneslives »

thefox wrote:Another idea would be to use the expansion port, but unfortunately it doesn't have the necessary signals. It has the data bus, but only A15 of the address bus. So you'd need a GameGenie-like device to pass more information via the EXP pins, but that kind of defeats the point of using the expansion port.
Are you sure about that? One thing I realized when working on my CICOprocessor is that you can infer the address from watching the data bus alone by snooping the opcode fetch cycles which contain all the address info. The expansion port also has /NMI & /IRQ signals so you'll know when the CPU is jumping to those vectors. The only thing you don't really have visibility to is when the APU frame counter IRQ fires, and DMC fetches. But perhaps if you're emulating enough of the 6502 to always keep track of what it's current address is, you could emulate those features as well.?
If you're gonna play the Game Boy, you gotta learn to play it right. -Kenny Rogers
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Sumez
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Re: RAM watching on a real NES?

Post by Sumez »

rainwarrior wrote: https://www.reddit.com/r/Tetris/comment ... stem_they/

In this thread there's a suggestion that the Game Genie is just used to apply a patch that controls the random number generator to make sure both players get the same pieces, and another poster says that the gathered stats and constructed visual is accomplished by analyzing the video itself, not by communication with the CPU.

Both of those ideas seem pretty plausible, and wouldn't require any special hardware.
It's always funny seeing people talking about their theories about how they do this, and most people who claim to know, obviously have no idea. We had people going on in the chat at CTEC too - we used a different solution for random pieces, but the ideas people had for how it worked are hilarious. :)

The hardware solution at CTWC is only to patch the game for though, not to parse data.
LittleRain wrote:Im not sure if any of you watch the Tetris world championships, but every single nes they have uses a game genie which they use to redraw the game in HD for an overlay for twitch. They also use the data to make cool stats like tetris percentage, and tracking droughts.
All of this is done using video recognition software. They capture footage using cheap USB composite capture devices, and clean up the footage and draw stats, etc.
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