Sega light gun vs XG-1

[phoenixdownita]

I recently made myself a sega light gun to Atari adapter following the popular advice that it's more precise.

I follwed the instructions here:

http://133fsb.wordpress.com/2010/05/08/sega-light-phaser-to-atari-xg-1-adapter

 

I have to say that I am not that sure it is more precise, it seems that from afar it is a tad more precise, from close up it has the same offset problems as XG-1.

I played on Alien brigade and it definitely offsets to the left.

 

I got the gun for less than 8 US$ shipped and I had in house all the material to make the adapter (I used a real inverter just because I happened to have one), so in the end after 2H or so of tinkering (I wanted to have a "proper" housing) I had it done.

Note: even if you use a real inverter instead of the 1 transistor you still have to pull up the input for the gun trigger with a 10K resistor or it wouldn't work, I forgot, shame on me.

 

Is it possible that on a 7800 Atari made the XG-1 work better? After all there's no Pokey to do the decoding.

 

Once I have a chance I'll give it a shot over the XEGS but for now I can say that the whole ordeal, unless you enjoy to tinker around, is not that worth your time, at least not for a 7800 .... maybe the cost could be a reason, but not the increased precision.

[Tempest]

I thought the accuracy of the light gun had to do with the game coding and not the gun itself? Interesting

[Trebor]

I have to say that I am not that sure it is more precise, it seems that from afar it is a tad more precise, from close up it has the same offset problems as XG-1.

I played on Alien brigade and it definitely offsets to the left.

 

I thought the accuracy of the light gun had to do with the game coding and not the gun itself? Interesting

 

 

Any chance of testing Crossbow, Barnyard Blaster, Meltdown, or Sentinel to see if those games provide the same/similar results?

[Jinks]

Any way to aim the xg1 so it is accurate?

[phoenixdownita]

 

 

 

Any chance of testing Crossbow, Barnyard Blaster, Meltdown, or Sentinel to see if those games provide the same/similar results?

 

Crossbow: from a little afar it is better with Sega, from close up too much offset (maybe is a different delay)

Meltdown: much better with XG-1, you need to be close to aim to those little suckers anyway

Sentinel : better with Sega, can play form a little afar, not by much but I managed to get to the level 4 boss (level Easy) but that son of a b... is hard as hell [the whole second part of level 4 is a little out there for being "easy")

 

Barnyard Blaster: didn't test, don;' like the game and XG-1 works well enough last I tried.

 

FYI I am playing on a very small screen, say 14", when I say close I mean 2/4 inches, when I say far I mean 1 foot or so

 

Your mileage may very.

Edited June 11, 2014 by phoenixdownita

[phoenixdownita]

Attached a picture of my home made adapter.

 

The darker line in the middle is hot glue to join the 2 plastic halves, inside I used a PCB that runs the whole length of the converter, the connectors are soldered to the PCB (the bottom 4 pins).

As inverter I used an 74HCT1G04 (smd) over a SOT753 adapter so I can solder it on normal PCB.

Edited June 11, 2014 by phoenixdownita

[thucom]

by sheer stupidity(not realizing the atari light gun I had gotten had a factory original miswired trigger wire in the plug) I ended up making a hybrid gun. The cord and trigger of an atari gun with all the other parts from a sega light gun. I beat alien brigade first try when I got it. Still doesn't feel terribly precise when dealing with crossbow, it kind of feels like we need a crosshair with some of the itty bitty moving targets there, but I was impressed.

[Shawn]

Attached a picture of my home made adapter.

 

The darker line in the middle is hot glue to join the 2 plastic halves, inside I used a PCB that runs the whole length of the converter, the connectors are soldered to the PCB (the bottom 4 pins).

As inverter I used an 74HCT1G04 (smd) over a SOT753 adapter so I can solder it on normal PCB.

 

 

Try turning the brightness up on your TV might help with the responsiveness of the gun from distances.

[Paul Westphal]

The "best" light gun is the one from Best Electronics. they are more accurate than the stock ones.

[BenjaminR]

I agree with Paul Westphal,

 

The light gun that "Best Electronics" sells are more accurate than the XE gun, especially with Crossbow. I have used both guns and prefer the "Best" version. It may look a little cheesy, but it works well.

[Prosystemsearch]

Why not put in a regular Sega Master System Light gun inside the port of the 7800?? Why won't it work??

[phoenixdownita]

Why not put in a regular Sega Master System Light gun inside the port of the 7800?? Why won't it work??

 

Because

http://133fsb.wordpress.com/2010/05/08/sega-light-phaser-to-atari-xg-1-adapter/

[Jinks]

Why not put in a regular Sega Master System Light gun inside the port of the 7800?? Why won't it work??

All unmodified controllers for 2 button and non atari light guns will not work on the 7800. There are tons of documents, schematics, threads on atari age about it.

Edited June 14, 2014 by Jinks

[CPUWIZ]

Why do you guys even bother to keep replying to his questions? LOL

 

A simple google or AA search would have given the answer quicker than a forum post.

[ColecoGemini]

I love all these unwritten rules certain Internet forums have.

 

"Don't answer questions that have been answered once, 15 years ago, on a Geocities homepage some retrogamer made that has since been deleted."

 

Or the famous forum conundrum: "Don't start new threads on a subject that had a thread 4 years ago because you're being redundant, but also don't necro-bump older threads because it's bad forum etiquette. Just read what others wrote and shut up."

 

Some days it's almost like most of these retro gaming forums should have a huge disclaimer "Just don't post anything unless you're part of the pre-established cool kids clique. In fact, don't even register. Just go back to digitalpress forums, peasant."

[CPUWIZ]

Not rules, MY OPINION. Very different.

 

I just want to know why the 5200 controller doesn't work on the 7800.

[Jinks]

Not rules, MY OPINION. Very different.

 

I just want to know why the 5200 controller doesn't work on the 7800.

Cause the 5200 has a phone number pad on the controller and the 7800 needs a rotary phone signal.

[Andromeda Stardust]

Well I was playing Sentinel (NTSC proto) on my "Best" AV modded 7800 using my mom's 27" CRT with a "Best" light gun. The gun continually hits roughly two-and-a-half inches to the left of wherever I'm pointing it. Even if I tough the freakking screen with the tip of the gun, the blast is 2.5 inches to the left. Apparently it appears there is a timing issue with racing the beam. There appears to be no options at all for horizontal calibration of the gun. I assume it may or may not be like this for all games. The only workaround I can think of is to aim just to the right of the target. It is very possible this offset may be more or less depending on the TV or 7800 console used. The aim could easily be corrected in software by shootting onscreen crosshairs before starting the game. SNES Super Scope games all use a calibration screen.

 

I've got more 7800 lightgun games on the way if Atari2600 didn't take weeks to ship out people's orders.

 

Maybe the offset could be corrected by adding a slight delay inline with the signal? An RC low pass filter on the light sensor (tuned somewhere below the 3Mhz colorburst frequency) might work to add a very slight response lag but IDK if adding slight lag will move the aim right or left. Adding a filter could just as easily make the aim worse.

Edited July 28, 2014 by stardust4ever

[Jinks]

Why not somehow adjust the guns aim to the right. All 7800 games shoot to the left.

Is there anything internal that can be adjusted in that way?

[Trebor]

Some high resolution/detailed pictures of the internal hardware of the XE Light gun are here for those interested.

 

It's a shame because in theory and (proper) practice the 'Cathode Ray Timing' (XE/8-bit Light gun(s), SNES Super Scope, computer light pens) should be more accurate and precise than utilizing a 'Sequential Targets' method (NES Zapper).

 

More details here.

 

It's just another missed opportunity by Atari. Nonetheless, two things to note and recommended regarding utilizing Atari (compatible) Light guns... 1) a ~3 feet distance from the screen and 2) turn up the brightness of the display.

 

Although a NES Zapper could not be converted for use on the 7800 due to the different methodologies/technologies applied, it would be interesting to see if a SNES Super Scope could perhaps be modified to work, since it's the same light gun design/detection.

[RevEng]

Maybe the offset could be corrected by adding a slight delay inline with the signal? An RC low pass filter on the light sensor (tuned somewhere below the 3Mhz colorburst frequency) might work to add a very slight response lag but IDK if adding slight lag will move the aim right or left. Adding a filter could just as easily make the aim worse.

Putting a delay on the sensor input would have the effect of the system thinking the gun saw the passing electron beam later than it actually did. Since the beam travels from left to right, this would result in shifting the gun's "aim" to the right. Just bear in mind that if you delay the signal so much that the actual aim+delay wraps on to the next scanline, it will shift the aim to the left. (and slightly down)

 

I think given the brief nature of the signal vs the relative amount you need to delay it, an RC delay probably won't work.

[Andromeda Stardust]

^^ I was thinking maybe due to phosphor persistence, the afterglow during the proceeding few microseconds might be strong enough to hold the signal until it is strong enough to pass the filter. A brief spike, however, would likely get filtered out.

 

I'd need to get my old electronics textbooks out to see what RC time constant I would need to aim for. I have no idea what the duration it takes the beam to travel 2.5 inches on a 27" CRT. An inline 10K trim pot and a very small capacitor to ground might do the trick but it also depends on what the voltage threshold is for the detection circuit. However the circuit would take a square digital waveform and convert it to a fuzzy analog hump. If the RC time constant is longer than duration of the "hump," the signal may not even reach the required voltage threashold to trip the digital logic.

[RevEng]

I did a back of the envelope calculation. You're looking at shifting it about 1/10th of the screen width. There are 320 7.16Mhz color clocks across the width of the visible screen. Each clock takes 140ns, so 32 of them would take 4480ns.

 

I don't know exactly how long the detector is activated by the beam, but I think it would need to be relatively brief for a useful horizontal resolution.

 

You could always go old-school and rely on propagation delay. Just run the signal through 2240 feet of wire.

[Rybags]

The light pen resolution as reported by Antic is 2 scanlines / 2 hires pixels (both registers only report 8 bits)

[RevEng]

You could probably implement a delay for this fairly cheaply with an 8-bit shift register. Just clock it at some sub-scanline rate, and tap the "bit" corresponding to how many clocks of delay you want.