Light guns hit home video game consoles with Shooting Gallery on the Magnavox Odyssey in Because the included shotgun-style light gun was only usable on a Magnavox television, the game flopped. While older light guns like the Ray-O-Lite rifle emitted beams of light, the Zapper and many other recent light guns work by receiving light through a photodiode on or in the barrel and using that light to figure out where on the TV screen you're aiming.
When you point at a duck and pull the trigger, the computer in the NES blacks out the screen and the Zapper diode begins reception. I pulled my old NES out of storage to play some classics and decided to start with the very first cartridge, the combo Super Mario Bros. Super Mario Bros. Not a single one.
I was convinced the zapper was broken but then I plugged the NES and zapper into an old s-era tube television out in my garage and, behold, the zapper works!
From my little test I know enough to say that the issue seems to be a CRT vs. HDTV issue, but I have no idea why. A lot of people, and certainly most of the kids that played the NES back in the day, were under the impression that the Zapper actually shot something towards the television, much like a TV remote sending a signal to a television set. The Zapper does nothing of the sort and what, exactly, on the television would be able to receive the signal and send it to the NES?
The only connection between the Zapper and the NES is the cord, and for good reason. This was true of all light-gun accessories for all video game systems of the era and preceding it. They were all just simple light sensors housed in deceptively gun-like cases. Does that mean the Zapper was actively tracking all those ducks on the screen with surgical precision?
Nintendo designers came up with a very clever way to ensure the simple sensor in the Zapper could keep up. Every time a player pulled the trigger on the Zapper, the screen would for just a fraction of a second blink black with a large white targeting box drawn over everything on the screen that was a valid target such as the ducks.
It repeated the process, all within that fraction of a second, for every available target on the screen. If the box was centered enough, it counted as a hit. If the target box was outside of the center zone, it was a miss. It was a very clever way to deal with the limitations of the hardware and provide a fluid user experience. Unfortunately, despite being clever, it was very hardware dependent. Much like early PC video game designers used hardware quirks to help build their games like knowing the clock speed of the platform they were working on was fixed and could be used to time in-game events , Nintendo and other early game companies relied heavily on the quirks of CRT displays and their respective display standards.
Specifically, in the case of the Zapper, the mechanism is completely dependent on the characteristics of CRT display. First, it requires extremely precise timing between the trigger pull on the Zapper and the response on the screen.
The original timing sequence was based on the very dependable response time of a CRT hooked up to the analog NES signal.
Whether the old tube TV was big, small, cutting edge or 10 years old, the speed of the signal via the CRT display standard was reliable. By contrast, the latency in modern digital sets is not reliable and is not the same as the old consistent delay in the CRT system. However, this latency completely destroys communication between the Zapper, the NES, and the events on the screen.
This extremely precise timing was possible and consistent because Nintendo designers could count on the refresh rate of the CRT being consistent. CRT displays use an electron gun to activate phosphors in screen hidden behind the display glass. This gun sweeps across the screen from the top to the bottom at a very dependable frequency. Even though it happens faster than the human eye can detect, every single frame of every single video game or television broadcast is displayed as if some hyperactive robot is drawing it line by line from the top to the bottom.
By contrast, modern digital displays make all the changes simultaneously. They are displayed all at once in their respective standards. The light sensor uses that black screen as a reference point, which helps it account for the wide variety of lighting situations in the rooms where the game is being played.
In the next frame, the area the duck occupied turns white while the rest of the screen remains black. If the light sensor detects light in that second frame, your gun is on target. If the light sensor does not, the dog is going to laugh at you. When there are two ducks on the screen, three frames are used. The game will show a black screen, then a black screen with one of the ducks turned into a white square, and then a third frame with the other target illuminated.
That's it. Such a simple device. It's really a shame they've never improved on video games since then.
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