nesdev.org

I just thought of a fun idea, a take on the modern DLC or user created content and NES games.

What some space was set aside in battery backed RAM for additional downloadable content, say extra levels and stuff. Then you could make your players download the extra material by for example pointing a Zapper at a youtube-video just flickering white for 1s and black for 0s with some kind of sync signal at the beginning of the video.

OK, sure - 1KB of data would make you point the zapper at the screen for 4 minutes at 30fps, but it would be a fun experiment. Plus it would be a really seizure inducing video But you could put a nice tune to it to make it more fun to sit there with your zapper.

I am not a big fan of DLC in modern games, but it would be cool to let other people make puzzles for a puzzle game or levels for other types of games. User created stuff can often be as good as the original content. You could easily ship a level editor and have it generate a video file to upload.

I haven't figured out any other good ways to get the data from the internet into a NES cart using stuff people usually have at home. Perhaps the mic on the Famicom would work.

What do you think? Am I crazy? Would this type of thing even work?

I think it is a clever and interesting idea, but I have concerns about LCD displays that aren't too good in changing between black and white fast.

I guess that's true, but they should be able to handle 30fps ok, even the worst monitors.

I do wish someone would make a ram cart plus transfer cable for controller port 2, but maybe there's no point if it takes like 5 minutes to transfer a 256kb rom to the cart. And I'm pretty sure someone (Blargg?) made a boot loader for such a thing.

I don't think the Zapper would work at all. I seem to remember it relying on the 15.7 kHz horizontal scan frequency of a CRT SDTV.

As for blargg's bootloader, thefox mentioned it in this post. But then you'd have to build a bunch of cables and include one with each copy of the game.

tepples wrote:I don't think the Zapper would work at all. I seem to remember it relying on the 15.7 kHz horizontal scan frequency of a CRT SDTV.

As for blargg's bootloader, thefox mentioned it in this post. But then you'd have to build a bunch of cables and include one with each copy of the game.

OK, I don't really know much about how the zapper works. I thought you could just read it at any time and check wether or not it detected light. If it relies on timing of the composite signal, then I guess the idea will have to be reimagined in some other way. I'll try and read up on how it works.

Isn't it basically just a photosensor directly connected to a port, and only software is the thing that relies on specific TV timings to determine the hit position? In this case it should work just fine to detect black/white changes, as position does not matter there.

I thought it was a photosensor connected through a resonator. But then I haven't done much testing with light sources other than a CRT SDTV.

I never messed with the original Zapper as well, only fixed tons of clones for Famiclones, they had broken cords/plugs for the most part. In those, there was no resonator, just a sensor, transistor, and a couple resistors. In the past I have heard many times that people were able to fake hit detection by pointing the sensor on a light bulb.

From what I can gather from the wiki, one can read the zapper at any time and see if bit 3 is set or not. The implementation of hit detection in games seem to vary from timed code to simply checking if you hit anything white during the entire frame. So it looks like it should work. I will probably do some tests with this, I just need to get a working zapper.

When you fire the zapper in most games you can see white target boxes which flash on the screen briefly. Games may check to first make sure the zapper sees no light, then light for a particularly frame. If you only detected hits if the zapper saw light, you could point the zapper at a traditional light bulb and just pull the trigger. I have heard that flicker light, perhaps a florescent light could unreliably register false hits.

That's an interesting way to try to download data. But I don't think the light from a modern digital TV (LCD and Plasma) works with the zapper. The light from a CRT is more intense. Newer lightguns actually have more complex logic behind how they function. The NES Zapper is pretty simple.

How could a light not work with a photosensor? Even if it is too dim (lower contrast ratios are there indeed), just put the Zapper closer to the screen.

All the complex stuff in modern light guns is there only to provide a good precision, which is not needed in this case at all.

Should be easy to test on hardware, provided you've got a zapper and some dev cart (e.g. PowerPak).

The test I imagine is: each, say, 30 vblanks, toogle the display from all black to all white and vice-versa. Continuously poll the "detection" bit, as soon as it is set, output a loud beep, otherwise silence. The slowly flashing screen is to verify that the "beeper" code works reliably when the zapper points the TV, then after we can see if it beeps when the zapper points a bright light source.

The Zapper contains a 16kHz resonator of some sort, equivalent to the exact same parts used by your infrared remotes, just using a photodiode that's sensitive to visible light instead of infrared.

It is very unlikely that it will work with an non-CRT-SDTV, although given how most NES games used the zapper, it should be possible to modify one to work with a modern TV.

That's interesting. I found Zapper schematics, and it is way more complex than the one found in clones, it has a demodulating IC or something (no resonators are seen, though). Sega Master System also had very complex schematics with six transistors. The clones had only R2, R4 and Q1 from the Zapper schematics, with photosensor connected to the base of the transistor.