A VGA converter that works with the atari 8-bit!

[puppetmark]

Rybags has done a lot of video signal testing, it may be worthwhile to search his video-oriented messages here, to reach a solution.

 

I've always had a nice crisp picture from the monitor port of my original non-XL 800. In fact, I remember that when the XL came out, a lot of former 800 owners said that the video quality on the XLs & later, the XEs was not as nice as the that of the original 800.

 

While they don't have as much RAM, they do have the nicest feeling keyboard of the series (it is mechanical, with leaf switches, not Mylar). Over-all, they are very well-designed & well built machines. Mine still works great after nearly 30 years.

 

It would be interesting to see if the 800s exhibit the same video issues as the XL/XE with this VGA device. Since the later machines implemented a lot of cost-cutting manufacturing techniques, my intuition is that the 800 would work perfectly.

 

Just a guess, but worth trying, if you have one in a box in the attic.

 

If it does work perfectly, this experiment should give you enough info to deduce how to correct the issue on the later machines, by researching the changes made to the video circuitry on the XL.

 

Good luck, & interested to hear your findings...

 

Those are good suggestions. I have schematics for all the 8-bits and I can tell you that my modified 600XL is very close to the 800 video circuits, so I think you are correct in that an 800 would give good results. unfortunately, I do not have an 800 to test with. I suspect removing the video modulator from the 130xe and replacing it with proper chroma and luma video amps equivalent to the 800 or super video XL upgrade will give nice results.

Edited September 24, 2008 by puppetmark

[Rybags]

My testing was only on the luma signal as I wanted to know what was going on with sync signals when running 240 line hires.

And it was with my PC sound input, so it can only sample 200 KHz.

 

It would be interesting how games go on it. Something like Rescue on Fractalus or Ballblazer might be a good indicator as they both have large moving areas.

 

Does the device have any sort of adjustment so far as how it does the de-interlace?

 

Also, it might be interesting to test my earlier theory of whether you can "fool" it into doing 480 line perceived video, although the de-interlace might simply de-comb the alternate frames and/or blend scanline pairs together.

 

I've been meaning to do a program to test it since my capture card has an interlace control slider which adjusts the way it does frame combining.

 

Agreed on earlier comments re colour attenuation. I guess a problem there is that the Atari doesn't have such great saturation to begin with, so if you take action there you might make things look even more washed out than they already are.

[+Stephen]

Please, the best test for the de-interlacer on this is to just fire up FlickerTerm and see if the characters line up. Do a solid line of dashes or underscores, and see if they are stepped or flat. If flat, it is correctly handling the output of the Atari. If you need an image, let me know and I'll ZIP one up.

 

Stephen Anderson

[atariksi]

So I did some initial testing last night on this converter and this is what I found:

 

I tested a super video 130xe, stock 130xe, stock 65xe, and super video 600XL. Using the composite video from any atari doesn't produce a very good output. It is readable and perhaps usable but it has vertical lines, blury text and color bleed problems. The picture I took of that didn't come out. Connecting the Atari chroma and luma to the s-video input of the converter is the best option for any Atari that I tested. Some XL machines do not have chroma on there monitor ports but that can be added pretty easily. MetalGuy is right, disconnecting the composite video circuit helps clean up the verticle lines and color issues. However, in th 130XE and 65XE, that means disconnecting the video modulators which also cuts out needed video amps. The solution I came up with on my super video 130Xe was to replace L31 with a 84pf capacitor. it added just enough antenuation to cancel out 99.9% of the vertical lines. The best results came from my super video 600XL with the composite circuitry disconnected and the chroma and luma going to the converter input. One more interesting observation I found is that when I first switch on the Atari, the "ready" prompt flickers a bit for a few seconds. I think its the motion-adaptive de-interlacer kicking in.

 

Here are some pics:

 

This is my super video 600XL and CRT monitor

 

This is my super video 600XL on my Acer X163wb

 

this is a stock 130xe. The stock 65XE looks identical

this is my super video 130xe

 

this is my super video 130xe with 84pf cap intstalled in place of L31

 

I know these aren't very exciting but I wanted to test some different machines initally and see what he have. SO far, I am impresses with this little box. I will do some more testing including flickerterm. I also will test omniview XE and some hirez pictures as well. Let me know if there are other apps anyone wants tested, I will do my best to accommodate.

 

How about narrow and wide modes like POKE 559,35 or POKE 559,33 to see how it deals with overscan? I have an LCD that just cuts off video in certain VGA text modes.

[puppetmark]

Here are some pics from Flickerterm. I would have posted them earlier but I have been sick with the flu. Anyway, it looks like the characters are stepped.

 

[a8isa1]

Here are some pics from Flickerterm. I would have posted them earlier but I have been sick with the flu. Anyway, it looks like the characters are stepped.

That's what my current scan converter does. I was hoping this one would do better.

[+Stephen]

Here are some pics from Flickerterm. I would have posted them earlier but I have been sick with the flu. Anyway, it looks like the characters are stepped.

That's what my current scan converter does. I was hoping this one would do better.

 

#@&%! If I had waited two more hours, I would not have bid on this. Oh well - now I have a 2nd uselses VGA doubler for my 8-bits.

 

Stephen Anderson

[Rybags]

Not totally useless.

 

Stepped graphics like that means that you can do page flipping and get interlaced 480 pixel vertical resolution.

 

Not so great for FlickerTerm, but good for doing hires static graphics.

 

Can you run some APAC and TIP graphics stuff?

[puppetmark]

Not totally useless.

 

Stepped graphics like that means that you can do page flipping and get interlaced 480 pixel vertical resolution.

 

Not so great for FlickerTerm, but good for doing hires static graphics.

 

Can you run some APAC and TIP graphics stuff?

 

Here are some RIP and Your Hi resolution Jess1 and simpsons. These are all on my Acer LCD monitor. the TIP images I had would not display with this converter or my composite monitor either. It looks like they are looking for PAL hardware. Any links to some TIP images for NTSC hardware would be helpful.

 

Here are some 160 x 200 RIP images. These looks great. Rock solid and very clear.

 

Here are the Hi resolution images. On the LCD there is a very slight flicker but on a CRT VGA monitor there is none.

Edited September 28, 2008 by puppetmark

[oldschool84]

Not totally useless.

 

Stepped graphics like that means that you can do page flipping and get interlaced 480 pixel vertical resolution.

 

Not so great for FlickerTerm, but good for doing hires static graphics.

 

Can you run some APAC and TIP graphics stuff?

 

Here are some RIP and Your Hi resolution Jess1 and simpsons. These are all on my Acer LCD monitor. the TIP images I had would not display with this converter or my composite monitor either. It looks like they are looking for PAL hardware. Any links to some TIP images for NTSC hardware would be helpful.

 

Here are some 160 x 200 RIP images. These looks great. Rock solid and very clear.

 

Here are the Hi resolution images. On the LCD there is a very slight flicker but on a CRT VGA monitor there is none.

 

 

More importantly, how does AR the City and Bruce Lee look???

[oldschool84]

So I did some initial testing last night on this converter and this is what I found:

 

I tested a super video 130xe, stock 130xe, stock 65xe, and super video 600XL. Using the composite video from any atari doesn't produce a very good output. It is readable and perhaps usable but it has vertical lines, blury text and color bleed problems. The picture I took of that didn't come out. Connecting the Atari chroma and luma to the s-video input of the converter is the best option for any Atari that I tested. Some XL machines do not have chroma on there monitor ports but that can be added pretty easily. MetalGuy is right, disconnecting the composite video circuit helps clean up the verticle lines and color issues. However, in th 130XE and 65XE, that means disconnecting the video modulators which also cuts out needed video amps. The solution I came up with on my super video 130Xe was to replace L31 with a 84pf capacitor. it added just enough antenuation to cancel out 99.9% of the vertical lines. The best results came from my super video 600XL with the composite circuitry disconnected and the chroma and luma going to the converter input. One more interesting observation I found is that when I first switch on the Atari, the "ready" prompt flickers a bit for a few seconds. I think its the motion-adaptive de-interlacer kicking in.

 

Here are some pics:

 

This is my super video 600XL and CRT monitor

 

This is my super video 600XL on my Acer X163wb

 

this is a stock 130xe. The stock 65XE looks identical

this is my super video 130xe

 

this is my super video 130xe with 84pf cap intstalled in place of L31

 

I know these aren't very exciting but I wanted to test some different machines initally and see what he have. SO far, I am impresses with this little box. I will do some more testing including flickerterm. I also will test omniview XE and some hirez pictures as well. Let me know if there are other apps anyone wants tested, I will do my best to accommodate.

 

Where is L31 located at? Hard to see when all the components are located over top of the markings.

 

I just performed the 'Super Video' mod and would like to install the 84pf cap as well.

 

Thanks!

[Kjmann]

I would be curious to see how a game like "Lode Runner" or "Choplifter" Works on this with the artifacting graphics.

[puppetmark]

Where is L31 located at? Hard to see when all the components are located over top of the markings.

 

I just performed the 'Super Video' mod and would like to install the 84pf cap as well.

 

Thanks!

 

answered here:

 

http://www.atariage.com/forums/index.php?showtopic=131906

[+Stephen]

I would be curious to see how a game like "Lode Runner" or "Choplifter" Works on this with the artifacting graphics.

I have a different VGA doubler, but artifacting works perfectly fine when using composite input, and doesn't work at all (as expected) when using separate luma/chroma. I would imagine this device would work the same way.

 

Stephen Anderson

[flashjazzcat]

Is there any reason to suppose this won't work with the A8?

 

S-Video to VGA Converter

 

Certainly a cheaper option than buying a new TV/Monitor with component inputs.

[Tickled_Pink]

If I was to have a quick guess, it should work. S-Video has the same pins as the XL/XE monitor output, just in a different order.

[flashjazzcat]

Yep - no problem with the connection from the Atari to s-video/component (I have a cable for that and it works well). What I'm really wondering is if there are any peculiarities about the Atari signal that might cause problems with the VGA converter itself.

[+David_P]

I just picked up one of these:

 

http://www.dealextreme.com/details.dx/sku.17894

 

and have no complaints to date. Tried a few 800xls and an 800; looking at the 800xls reminds me that I need to do the SVideo upgrade...

[mimo]

Yep - no problem with the connection from the Atari to s-video/component (I have a cable for that and it works well). What I'm really wondering is if there are any peculiarities about the Atari signal that might cause problems with the VGA converter itself.

There are quite a few discussions about this here. My take is that the Atari video output is out of standard by todays standards.

Some TVs cope ok, some do not, I guess that these converters could have the same issues.

[Tickled_Pink]

Yep - no problem with the connection from the Atari to s-video/component (I have a cable for that and it works well). What I'm really wondering is if there are any peculiarities about the Atari signal that might cause problems with the VGA converter itself.

There are quite a few discussions about this here. My take is that the Atari video output is out of standard by todays standards.

Some TVs cope ok, some do not, I guess that these converters could have the same issues.

After my experiences with the Wii and 360 I'm wondering if there really is a different standard on today's TVs, particularly the CRT units. Neither the Wii or 360 would work directly from SCART on either of the 21" CRT TVs we have (although both work faultlessly on a newer 15" CRT) unless they are first patched through our DVD Recorder.

[+Stephen]

It will work, but there are issues. I have tried two and Steve Sheppars has tried a third. They all exhibit the same behaviour. Since the Atari doesn't output a true interlaced signal, every other frame is dropped down by one scanline. This makes the text in FlickerTerm look terrible. But there is an advantage. No flicker on the interlaced modes since it combines frames. Also, all the adapters I have seen are PAL&NTSC compatible.

 

Stephen Anderson

[flashjazzcat]

Well, should be an interesting experiment. It was cheap enough!

[flashjazzcat]

Well, it arrived and was a VGA to S-Video converter, not the other way around. Fortunately, the seller will refund on the basis of my scrutinisation of his (perhaps unintentionally) misleading description. S-Video to VGA converters all seem to be either from Hong Kong sellers or rather expensive.

[a8isa1]

Well, it arrived and was a VGA to S-Video converter, not the other way around. Fortunately, the seller will refund on the basis of my scrutinisation of his (perhaps unintentionally) misleading description. S-Video to VGA converters all seem to be either from Hong Kong sellers or rather expensive.

ouch

 

My "converter" was originally a settop box but for VGA, goes between a PC and its monitor. A couple of years ago the turner died so now I just use it for svideo/composite video conversion to VGA. It works well enough to play games, i.e. no lag, and has pretty sharp text. It's not quite a match for a real y/c monitor but then I don't need the space for that monitor.

 

- Steve Sheppard

[ivop]

I just picked up one of these:

 

http://www.dealextreme.com/details.dx/sku.17894

 

and have no complaints to date. Tried a few 800xls and an 800; looking at the 800xls reminds me that I need to do the SVideo upgrade...

 

I received this one today and both my stock PAL 600XL and stock PAL 800XL do not work properly (the 600XL a little better though, it sometimes gives a static image). The device is working though, because I get a very clear picture when I connect it to my DVD-player. Not sure what the problem is yet. I think the signal coming from the Atari is too strong. If I pull the CVBS signal down through a small resistor, I get an image everytime I dis/reconnect it. Perhaps I'm going to try running it through an old VCR first and if that works, I'll try the SuperVideo upgrade.