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2600 video problem


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#1 Dastari Creel OFFLINE  

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Posted Wed May 2, 2012 9:23 PM

My 2600 is a pre-modded version where the output has been replaced with composite out. I had what I thought to be a power problem but it turned out to be an entirely different problem that is now fixed. Here's my problem now though. The video image seems to be waaaay off-center. It seems to be shifted to the right and up. I've tried on 2 CRT TV's. One is a 20" and the other is a 32". Its not shifted in the sense that the video appears off the right side of the screen and then ends up on the left. It seems to be more like the image is scrunched up on the upper left so I'm not missing any content, its just jarring to look at.

The reply from Best Electronics, the sales group was:

A. Talked to our Atari Super tech about this symptom. He said that is normal. When the 2600's were 1st designed 25 to 30 years ago, the largest CRT TV's at that time was around 19 to 25 inch hence the 2600 Broadcast screen display was mapped for that size screen. When you now display on a much larger CRT, there is some parts of the larger CRT that are not used. If you were to get a full screen on a newer TV, you would find the display larger but distorted from pushing the 2600 display larger that what it was designed to display at.

I also see a blue vertical line down the left of the TV. The response was:

A. The Vertical line varies on different Atari 2600 game cartridge displays. Atari 2600 Moon Patrol, Atari Missile Command and Atari Space Invaders are some of the Atari made Game Cartridges that do have the Vertical lines. Most of the Atari 2600 game cartridges do not have that tell tale Vertical Lines. This vertical line was a 2600 game programming code results. At that time the Atari 2600 programmers only had about 4K or 8K of total game ROM memory. So to get the most of that small of ROM memory, they did some programming tricks to save the usable ROM memory, that caused the vertical lines on the 2600 Screen display.

My concern is that they said this is because TV's these days are larger than 25" but one of the TV's that I tested was 20". Also there is no difference between how it displays on a 20" versus a 32" TV. Are they right that this is normal? Are the blue vertical lines normal? I just want to make sure that I'm not getting taken for a ride here.

#2 Syntaxerror999 OFFLINE  

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Posted Thu May 3, 2012 4:16 AM

Something you should know about best... While they are a good source of parts, the guy that runs it is a subborn ass. Hes the kind of person that if you were on fire he'd tell you youre cold and need to put a coat on.

The lines thing he speaks of are a comb of BLACK HORAZONTAL lines that were a side effect of the HMOVE command. Blue vertical lines? Never seen that. and Ive never heard of the screen scrunching issue... And I use my non modded atari on a modern LCD.

It all sounds like a biproduct of the composite mod hes using, and he doent want to admit something is wrong...but dont quote me on that. What say you Atari community?

Little background info with my own dealings. I bought a copy of the field service manual which he advertises as being for the 2600, 2600A, and JR. It does not cover the JR, I tried to inform him of this and he insists Im wrong like I was demanding a refund... Which I wasn't.

Edited by Syntaxerror999, Thu May 3, 2012 4:31 AM.


#3 Dastari Creel OFFLINE  

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Posted Thu May 3, 2012 11:38 AM

Something you should know about best... While they are a good source of parts, the guy that runs it is a subborn ass. Hes the kind of person that if you were on fire he'd tell you youre cold and need to put a coat on.

The lines thing he speaks of are a comb of BLACK HORAZONTAL lines that were a side effect of the HMOVE command. Blue vertical lines? Never seen that. and Ive never heard of the screen scrunching issue... And I use my non modded atari on a modern LCD.

It all sounds like a biproduct of the composite mod hes using, and he doent want to admit something is wrong...but dont quote me on that. What say you Atari community?

Little background info with my own dealings. I bought a copy of the field service manual which he advertises as being for the 2600, 2600A, and JR. It does not cover the JR, I tried to inform him of this and he insists Im wrong like I was demanding a refund... Which I wasn't.


I was afraid that this was the case. However, I found a screen shot of Moon patrol online that seems to be exhibiting the same characteristics that I'm describing. If you look at the screen shot below you see that the image seems to be shifted upwards and even though the display goes to the extreme right of the picture there is a visible dark bar to the left. Is this "off-center" quality typical for Moon Patrol? If so then it is not proof that there is something wrong with my 2600. I'll need to get another game ASAP to test it out.

http://www.atariprot...oonpatrol_3.png

#4 atari2atari OFFLINE  

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Posted Fri May 4, 2012 7:46 AM

How's this going, Dastari?

First off, I just wanted to put in a quick word for Bradley at BEST ELECTRONICS - - he IS a decent guy, but as Syntax points out, he CAN be a bit prickly.

I think nearly 30 years of dealing with ATARI fans has made him that way, though - - I mean, look at how some of the discussion threads around here flame up and end! :ponder: That said, I think he will treat you fairly, IF you come at him in the right way! I wouldn't "accuse" him, to start with, rather enquire, or ask for assistance in a friendly manner . . . if you get his defenses up, he may never come back down!

'Nuff said.

Back to the business at hand.


As Synatax pointed out, the HMOVE "cover-up" bar on the left - - that's normal, and was a trick to make the games look cleaner. Pop in SPACE INVADERS, and you'll see a "comb" on the left instead, where a full "cover-up" bar was not implemented.

Now, a "blue" bar - - I'm not certain I know what you mean. Maybe that black bar looks like a dark blue on your modern television? Not all TVs do a good job of showing true, deep blacks.


A picture, or a few dozen pictures, are worth a thousand posts, however. PLEASE take some shot of MULTIPLE, MULTIPLE games, and show us what you have going on!


I am hard pressed to think of any situation where a composite video mod has "forced" the picture into a corner of the screen.

And, based on your last post and the example you gave with MOON PATROL, that sort of positioning of the playfield is normal. ATARI games vary from game to game with their appearance, and how/where the different parts of the game are positioned.


What I HAVE run into is certain televisions and LCD screens have not liked the synchronization of the image, and so have "rolled" the screen when I tried to input a composite video modded 2600.

OR I have also run into certain modern televisions that upscale the image to fit the screen and washed out the colors or image.

I could imagine that the right (or wrong) settings on a modern television could "preserve" the size of the input image, too, and put it in one corner of a giant screen! Haven't seen it personally, but all things are possible . . .


Anyways, just trying to help, and I am mildly curious - - I do a lot of video mods, and am always wanting to know more.

Pictures, pictures, pictures! And, try a bunch of games and let us know how it goes . . .

:)

-a2a

#5 Dastari Creel OFFLINE  

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Posted Sat May 5, 2012 1:08 PM

How's this going, Dastari?

Now, a "blue" bar - - I'm not certain I know what you mean. Maybe that black bar looks like a dark blue on your modern television? Not all TVs do a good job of showing true, deep blacks.


The bar isn't blue. There's a blue vertical "line" that goes down the screen. The line is not completely vertical. There's a clean break about 1/2 of the way down and the line shifts a bit to the left and then goes the rest of the way down. Please see the attached picture (apologies for poor quality but its the best we could get on my digital camera)

http://i648.photobuc...ri/SAM_0142.jpg

The menu screen is the picture this shows up on best. This line also exists when I'm playing the game but for some reason its impossible to see on the photos that we took.

What you can see on the photos of me playing the game that you can't see on the menu is the "scrunching" that I mentioned. Please see this picture:

http://i648.photobuc...ri/SAM_0143.jpg

As you can see the picture almost goes to the right side of the TV, but there is a huge gap between the left edge of the picture and the left side of the TV. Is that normal? You'd think that it would be centered on the TV.

Also there seems to be a lot of gap between the bottom of the image and the bottom of the TV. Again, is this normal? When Best shipped me this game it came with the original gamebox. The pictures on the back of the box show the game perfectly taking up the entire TV screen. Is it supposed to look that way or did they doctor the image to make it look "cleaner" on the box. You'd think it would be so difficult to center the image...

As for other catridges, so far I don't have any. I wanted to confirm the Atari worked before purchasing any. Based on this information alone what do you think?

#6 Syntaxerror999 OFFLINE  

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Posted Sat May 5, 2012 2:18 PM

How's this going, Dastari?

First off, I just wanted to put in a quick word for Bradley at BEST ELECTRONICS - - he IS a decent guy, but as Syntax points out, he CAN be a bit prickly.

Agreed!

#7 atari2atari OFFLINE  

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Posted Sat May 5, 2012 2:54 PM


How's this going, Dastari?

Now, a "blue" bar - - I'm not certain I know what you mean. Maybe that black bar looks like a dark blue on your modern television? Not all TVs do a good job of showing true, deep blacks.


The bar isn't blue. There's a blue vertical "line" that goes down the screen. The line is not completely vertical. There's a clean break about 1/2 of the way down and the line shifts a bit to the left and then goes the rest of the way down. Please see the attached picture (apologies for poor quality but its the best we could get on my digital camera)

http://i648.photobuc...ri/SAM_0142.jpg

The menu screen is the picture this shows up on best. This line also exists when I'm playing the game but for some reason its impossible to see on the photos that we took.

What you can see on the photos of me playing the game that you can't see on the menu is the "scrunching" that I mentioned. Please see this picture:

http://i648.photobuc...ri/SAM_0143.jpg

As you can see the picture almost goes to the right side of the TV, but there is a huge gap between the left edge of the picture and the left side of the TV. Is that normal? You'd think that it would be centered on the TV.

Also there seems to be a lot of gap between the bottom of the image and the bottom of the TV. Again, is this normal? When Best shipped me this game it came with the original gamebox. The pictures on the back of the box show the game perfectly taking up the entire TV screen. Is it supposed to look that way or did they doctor the image to make it look "cleaner" on the box. You'd think it would be so difficult to center the image...

As for other catridges, so far I don't have any. I wanted to confirm the Atari worked before purchasing any. Based on this information alone what do you think?



Good news! What you are seeing is perfectly normal.

For the record, I'll just insert those pictures here, in case some day the hosting is lost - -

SAM_0142.jpg

SAM_0143.jpg


Thanks for providing those - - it really helps for troubleshooting!

The "blue line" you see is the break-point where the programmer(s?) tried to hide the HMOVE line.

The amount of "playable screen," well, that's indeed what you get with a good 'ole ATARI 2600!


Interesting experiment - - take some time and download STELLA, the ATARI emulator. Install it, and try out some of these games like MOON PATROL - - note in crisp, vivid VGA color where those breaks are, and just how much "playfield" you actually have. It's kind of a good thing to see and know about! STELLA is a great resource . . .


If you get a chance, pick up IAN BOGOST's "RACING THE BEAM" - - an amazing book that will teach you a lot about the limitations of the 2600 and how clever programmers worked with what they had!

http://mitpress.mit....ype=2&tid=11696



Anyways, I think you are good to go for some classic ATARI times!

:)

-a2a

#8 Dastari Creel OFFLINE  

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Posted Sat May 5, 2012 4:49 PM

Interesting experiment - - take some time and download STELLA, the ATARI emulator. Install it, and try out some of these games like MOON PATROL - - note in crisp, vivid VGA color where those breaks are, and just how much "playfield" you actually have. It's kind of a good thing to see and know about! STELLA is a great resource . . .


If you get a chance, pick up IAN BOGOST's "RACING THE BEAM" - - an amazing book that will teach you a lot about the limitations of the 2600 and how clever programmers worked with what they had!

http://mitpress.mit....ype=2&tid=11696


I know of Stella but I didn't see any point in getting it if I was going to get a the game system itself except possibly to play games that are homebrew/hacks that never had a cartridge release, but I figured getting a Harmony cartridge would solve that. I have a personal distaste for emulators since I prefer to play things on the original hardware. No matter how good a simulation of that hardware can be it will never quite be the same. That doesn't mean that I have anything against it, its just the reason why I normally don't look at emulators but you're right that in this case it may help me determine if something is intrinsic to a game or not.

As for Racing the Beam, I already have it but haven't gotten around to reading it yet. I am very interested in programming for the VCS. Its a life goal of mine to design at least one video game and I'd like to do it for the VCS since I have so many positive childhood memories of that system.

Edit: I got Stella as per your recomendation. As you suggested the "Playable area" problem shows up there as well so the game does appear to have not been designed to utilize the entire screen. However, I don't see the blue vertical line. Are you sure that this is a programming error and not some form of hardware problem? I would think that if it were a programming error then it would show up even on the emulated ROM.




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