The first duck falls, the second one drops, the third escapes… and the dog laughs right in our face. Blessed, cursed Duck Hunt and its endless hunts. But games like Duck Hunt on the Nintendo NES don't stand alone; they need the presence of a Zapper gun. Its operation seemed magical back in the mid-80s, and no TV would refuse its shots. Today, with LED screens dominating the world, the story is quite different. So what was the trick? Does the gun actually "shoot" or "receive"? The Slo Mo Guys have the answer…
The Nintendo Zapper dates back to February 1984, when it appeared in Japan under the original name Kōsen jū shirīzugan. The Western market had to wait until October 1985 to receive it, the same month the NES console debuted. That means the Zapper was a "launch product" for Nintendo in the United States, but not in Japan, with a difference of seven months.
On the surface, the operation of the Zapper is on par with many magic tricks. We aim, shoot, the duck dies. But there are no projectiles or anything like that. So, how exactly does the Zapper gun work? Thanks to a recent video published by the Slo Mo Guys, today we can see the full action in slow motion.
The Secret of the Nintendo Zapper
Personally, I think I'll never get tired of the cameras used by the Slo Mo Guys. We know well that each frame is drawn line by line on a CRT television from top to bottom and left to right, but seeing this at 10,000, 82,000, and 1,750,000 FPS, the situation changes completely. The so-called "perception of apparent motion" completes the illusion, since the TV processes one line at a time, but we observe a full screen.
Now, when we pull the trigger, the Zapper gun sends a signal to the console (which finishes drawing the last frame), and automatically presents a new black frame that covers the screen. The next frame is responsible for identifying a "valid target" by drawing a white square or rectangle over it, but keeping the black background.
If the gun's photodiode manages to register this change in light (that is, from the black frame to the detection of the white rectangle), the console counts a hit, generates a new frame that updates the score, and another additional frame with the updated sprite (in this case, the dead duck). What happens when there are multiple targets? The console draws the rectangles in different frames, thus avoiding detection errors.
In summary, the entire cycle of the Nintendo Zapper is reduced to four frames. The gun doesn't fire anything and the TV doesn't receive data. On the contrary, the gun is the "receiver". The design is so clever that Nintendo managed to use it as a menu control in Duck Hunt: If we shoot away from the TV, the gun changes the game mode, and shooting at the screen is equivalent to pressing Start.
(Editor's note: The image belongs to Kurayba on Flickr, CC BY-SA 2.0)
