Light guns and new TVs

[Miles Prower]

Well my 19in orion CRT has finally died and Im in the market for a new TV. But I need to know if the NES zapper and the SNES bazooka will work or not with an LCD or plasma TV? I have read conflicting reports on the question. I don't know if I can even get a new CRT anymore. I know the NES zapper detects light and dark so theoretically it should work with anything that emits its own light, but the SNES bazooka detects raster beams, so I don't know it actually requires an electron gun or if it will still detect the pixels being turned on and off by LCD screens. (Im assuming that LCDs draw frames in the same fashion as CRTs and that the gun detects the light and dark of the pixels being turned on and off. Im not certain though)

[+remowilliams]

No, classic light guns do not work on modern TVs (LCD/plasma/DLP, etc). They only work on older non HD CRT sets.

[Miles Prower]

Hmm, thats interesting because I always thought that the NES zapper worked by discriminating light from dark, so wouldn't it be able to distinguish a light spot from a dark spot on the screen?

[+batari]

Hmm, thats interesting because I always thought that the NES zapper worked by discriminating light from dark, so wouldn't it be able to distinguish a light spot from a dark spot on the screen?

It works by timing when the raster hits the spot where you are aiming. If it just detects light, how would it know which duck you shot when several are on the screen at once?

 

Anyway, the reason it does not work on some televisions is because they either scan the rasters differently or buffer/filter screen data, leading to timing differences.

Edited August 5, 2009 by batari

[Miles Prower]

I don't think its a matter of timing, as the timing wouldn't be affected by the size/resolution of the screen since the console produces a set resolution and the only way for timing to be effected would be if the consoles output was somehow distorted by the tv. I would think it would be more along the lines of the gun not being able to recognize light from dark on a LCD display for some reason. This is where I have heard conflicting reports. some say it can still determine light from dark on an LCD display and others say it has to do with the device actually detecting rasterbeam and photon discharges from phosphors on a CRT. If the gun simply detects light or absence of light then it should technically still work.

 

This also raises the question of will these guns work on a projection TV or a projector screen?

[+remowilliams]

some say it can still determine light from dark on an LCD display

It's more than just discriminating light from dark, as batari has posted above. Do a forum search 'light gun hdtv' if you want to see a couple other topic discussions.

 

This also raises the question of will these guns work on a projection TV or a projector screen?

No, same reason.

[Miles Prower]

Ok I see what you are talking about now. But is this because of high definition or because of lag time? I can't really afford a large HDTV and was just looking for a standard 21 in LCD or hopefully another CRT but I don't think CRTs are even manufactured anymore. So if its because of lag time then wouldn't a non HD LCD still work?

[BigO]

LCD's don't scan line by line in real time as the analog picture data is received by the TV. For display on a digital TV, the analog signal goes through all sorts of processing and buffering and assembling into memory to create a picture.

 

Light guns typically work because the console knows where the beam should be tracing on the screen at the moment it polls the gun to see if it's light or dark. With all that processing, not to mention an entirely different means of rendering the display, there's no way for the console to have any idea what should be on the screen at any given instant in time.

 

Search around the forums here. There's some really interesting and informative discussions on the subject.

[Miles Prower]

Even against the NES with a less than 1.75 MHz clock?

 

Is there any modifications that can be done to the light gun to make it work?

[RevEng]

The NES if plenty fast to detect the raster beam as it passes the view of the gun. Even ancient computers with light-pens used the same approach.

 

There are no modifications to make it work. Modern TVs no longer have raster beams.

 

That's why modern consoles don't have point-and-shoot gun games anymore, with the exception of the Wii which uses it's sensor bar instead of relying on a raster beam.

[Keatah]

A 1mhz apple ][+ (which has no video chips) is more than sufficient to make light-pens work.

[Miles Prower]

Well I went out today and bought a new LCD tv, and it most definately does not work with the zapper. I did go to various stores trying to find a left over CRT, esspecially since I could probably had gotten a 32 in for 200, but none were available. So I got a nice 22 in LCD for 240. Its a nice tv, Im not complaining but its basically a death sentence for duckhunt and possibly my yoshis safari game (but I haven't tested that one yet, so I can't be absolutely certain till I do)

 

Now I have one more question. Why do LCD screens look so grainy? I was actually rather dissapointed when I played my NES/SNES and the screen wasn't as sharp and crisp as a CRT. Im assuming its because its taking analog and converting it to digital, but techically shouldn't it look as precise as a handheld game? Hopefully someone knows what I am talking about.

[Rybags]

LCDs address pixels directly. They only look at their best if the signal coming to them is in their native resolution.

 

For a perfect example, try setting a PC LCD monitor to a resolution slightly lower than it's native rez, it'll look shithouse.

[Video]

Yeah, that's pretty much it, the signal is digital, which pixel to pixel is perfect, you can't beat LCD, but then it's taking an off image, sizing it to fit, which distorts the image, then many LCD's, at least the TV ones, have anti alising built in, and if you don't turn it off, it further degrades the picture, making LCD"s the worst option (and no modern TV's good options) for classic games.

 

As for scanning scanlines, I'd be more interested in how the sensor in the light gun opperates fast enough to detect anything to do with scanlines....as those things aren't exactly high tech or anything. Yeah, the processor is fast enough, assuming you give most the clock cycles to examining the 1/60th of a second the screen is blanked out, no I don't really see how the electronic eye is running that fast.

Edited August 7, 2009 by Video

[Tr3vor]

I dont think it will affect the SNES super scope. it uses the IR reciever on top of the tv, like the wii.

[tokumaru]

It works by timing when the raster hits the spot where you are aiming.

It's not as complicated as this.

 

If it just detects light, how would it know which duck you shot when several are on the screen at once?

The gun does indeed just detect light. Across several frames, white targets are drawn for each duck on a black background, while the gun is polled for light detection. There is only one target per frame, so if light was detected on that frame that was the target the gun was aiming at.

 

I believe the gun doesn't work because there is some delay caused by the video processing that is done on analog signals so the frame being displayed is not what the NES is expecting at a given moment.

[Video]

I always objected to the wholoe "reading a raster" thing with the NES zapper....if that's really true, how does it work with a light? (point it at a light and shoot, it will register a hit every time....purly reading light vs dark, cause the light certainly isn't sending out any raster anything)

 

As for sthe super scope, doesn't it use a wireless transciever or something to shoot with? I was thinking it worked in some uber oddball way, so it wouldn't really matter what screen you look at, as the gun never sees it anyways, just detecting which direction that your aiming....kinda like the Wii

[RevEng]

Yeah, from the reading I've done on this recently it seems there's 2 styles of lightgun. One kind - like the NES zapper - requires the game to flash objects white when the trigger is pulled. There's another kind that follows the flash of raster as it draws the screen.

 

It seems the zapper *should* work with LCD TVs, but I've heard reports to the contrary. Perhaps LCD TVs don't have a fast enough response time.

[gdement]

I think it really just depends on the game programming. It could time the raster, or it won't, depending how the programmer decided to do it. All the gun does is see light, beyond that it's up to the programmer.

 

Even if it's just doing the light/dark thing, it would still have issues from input lag. I would assume almost all LCDs are at least 1 frame behind, if not more. After all, it needs to wait until the whole frame has been received before it can start getting ready to think about putting it on the screen.

 

I always objected to the wholoe "reading a raster" thing with the NES zapper....if that's really true, how does it work with a light? (point it at a light and shoot, it will register a hit every time....purly reading light vs dark, cause the light certainly isn't sending out any raster anything)

Probably right, but..

a game could use light to detect a hit, and raster timing to determine the target. In that case using a light bulb would register a hit on whatever target comes first in the scan.

 

 

Raster timing seems like a better way to do it, since you'd only have to flash the screen for 1 frame. But they may not have bothered.

[tokumaru]

(point it at a light and shoot, it will register a hit every time....purly reading light vs dark, cause the light certainly isn't sending out any raster anything)

To prevent players from pointing the gun to a light bulb and getting a hit every time, games display a full black frame before drawing each target in white. If during that black frame light is detected, the player is surely not pointing the gun at the TV and no hits are considered.

[Atari Richie]

Its simple why they dont work there is only one reason and here it is....

CRT

Cathode Ray Tube Televisions and monitors have an electron beam that traces from left to right of the screen drawing a picture one line at a time.

You can use this affect to calculate the position of objects on the screen (I am keeping this simple)

LCD, Plasma and OED etc...

They update the whole picture area at the same time, all at once. And that is why old light guns dont work on modern TVs. Simple....

Edited August 29, 2009 by Atari Richie

[RevEng]

It definitely would be simple if the Zapper worked with the raster in the CRT. It doesn't appear to.

 

Quoth the wikipedia...

Sequential targets

------------------

The first detection method, used by the Zapper, involves drawing each target sequentially in white light after the screen blacks out. The computer knows that if the diode detects light as it is drawing a square (or after the screen refreshes) then, that is the target at which the gun is pointed. Essentially, the diode tells the computer whether or not you hit something, and for n objects, the sequence of the drawing of the targets tell the computer which target you hit after 1 + ceil(log2(n)) refreshes (one refresh to determine if any target at all was hit and ceil(log2(n)) to do a binary search for the object that was hit).

 

An interesting side effect of this is that on poorly designed games, often a player can point the gun at a light bulb, pull the trigger and hit the first target every time. Better games account for this either by detecting if all targets appear to match or by displaying a black screen and verifying that no targets match.

 

Cathode ray timing

------------------

The second method, used by the Super Nintendo Entertainment System's Super Scope and computer light pens, is more elaborate and more accurate.

 

The trick to this method lies in the nature of the cathode ray tube inside the video monitor (CRTs were the only affordable TV monitors in the late 1980s and early 1990s, when this method was popularized). The screen is drawn by a scanning electron beam that travels across the screen starting at the top until it hits the end, and then moves down to update the next line. This is done repeatedly until the entire screen is drawn, and appears instantaneous to the human eye as it is done very quickly.

 

When the player pulls the trigger, the computer (often assisted by the display circuitry) times how long it takes the electron beam to excite the phosphor at the location at which the gun is pointed. The light gun sends a signal after sensing the sudden small change in brightness of a point on the screen when the electron gun refreshes that spot. The computer then calculates the targeted position based on the monitor's horizontal refresh rate (the fixed amount of time it takes the beam to get from the left to right side of the screen). Either the computer provides a time base for the horizontal refresh rate through the controller's connector (as in the Super Scope), or the gun reads the composite video signal through a T-connector on the A/V cable (as in the GunCon 2). Once the computer knows where the gun is pointed, it can tell through collision detection if it coincides with the target or not.

 

Many guns of this type (including the Super Scope) ignore red light, as red phosphors have a much slower rate of decay than green or blue phosphors. As a result, some (but not all) games brighten the entire screen somewhat when the trigger is pulled in order to get a more reliable fix on the position.

 

Display timing is useless with plasma, LCD, and DLP, which refresh all pixels at the same time.

 

In any case, I don't see why some form of the "Sequential Targets" couldn't be tweaked to work with LCD and plasma TVs. The white-out time might have to stretch across 2 frames and be more visible to allow for laggy LCD pixels, but I don't see why it couldn't be made to work.

[gdement]

In any case, I don't see why some form of the "Sequential Targets" couldn't be tweaked to work with LCD and plasma TVs. The white-out time might have to stretch across 2 frames and be more visible to allow for laggy LCD pixels, but I don't see why it couldn't be made to work.

 

If we're talking about modern homebrew games, then that could certainly be attempted. I think the problem you'd run into though is that different displays have wildly different amounts of lag. So getting the timing to work would be an exercise in frustration.

 

You'd need to put the player through a calibration test to detect the screen's behavior. Then it might be workable. Calibration would need to test not only the lag, but how consistent it is (run the test several times). If the lag isn't consistent then the light/dark pattern would have to be pretty slow to cover the range of possibilities.

 

Incidentally, a program like that would be a cool way to objectively measure lag on all the TVs out there.

Edited August 30, 2009 by gdement

[BigO]

It’s simple why they don’t work there is only one reason and here it is....

CRT

Cathode Ray Tube Televisions and monitors have an electron beam that traces from left to right of the screen drawing a picture one line at a time.

You can use this affect to calculate the position of objects on the screen (I am keeping this simple)

LCD, Plasma and OED etc...

They update the whole picture area at the same time, all at once. And that is why old light guns don’t work on modern TV’s. Simple....

I keep half-expecting somebody to build an LCD controller that would let an LCD be a drop-in(ish) replacement for a CRT. It would be a neat trick.

Conceptually, you'd have to do an Analog to Digital conversion of the vertical and horizontal scan line signals (input to the CRT yoke) to address a single x,y element of the LCD controller then load the color data (converted from the CRT color gun control circuitry). I have no idea how close any existing LCD controllers are to being able to support the sequential loading of single elements at a fast enough rate.

 

Somehow, it would need to simulate the phosphor persistence characteristics.

 

You'd probably have to retain the physical yoke of the TV as I think it's inductive properties are part of the resonant circuits that run the scanning. For a true drop-in replacement, I guess you'd have to put hall effect or similar sensors in a container that fit in the yoke to sense the magnetic field without hard-wiring. That same package would have to simulate the load of the CRT filaments and read the color gun inputs. You'd have to have a series of the adapters that simulate different picture tubes.

 

A challenge that's way, way over my head. Maybe it's not a good idea, but I'd be surprised if I were the first one to think it might happen. Maybe it'll be done by some retrogamer trying to revive CRT games when the CRT's have gone extinct.

Edited August 31, 2009 by BigO

[Video]

One thing I'd like to know, does the Wii gun work on modern TV's (as the wii is intended for SD crt types...) Of course, modern consoles are powerful enough, it could literally take a picture of the screen and see if it is aimed at the right point when the trigger is pulled...