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The UAV Rev. D Video Upgrade Thread


Bryan

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3 minutes ago, x=usr(1536) said:

You're right.  That completely excuses you from being an ass for no very good reason at all.  My bad!

Sorry you found my jibe so offensive when it wasn't even written to you.  You must run into that problem a lot.

 

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3 minutes ago, Panther said:

Sorry you found my jibe so offensive when it wasn't even written to you.  You must run into that problem a lot.

Oh, I'm not offended.  Far from it.  In fact, I found it rather enlightening, though perhaps not in ways you might have intended.

 

Anyway, have fun interacting with people; it sounds as though you'll have a real blast with that! :waving:

 

Edited by x=usr(1536)
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2 minutes ago, x=usr(1536) said:

Oh, I'm not offended.  Far from it.  In fact, I found it rather enlightening, though perhaps not in ways you might have intended.

 

Anyway, have fun interacting with people; it sounds as though you'll have a real blast with that! :waving:

 

Will do, thank you.

 

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11 hours ago, Panther said:

What does it take to get NTSC artifacting working with the UAV's s-video?  A number of people have repeated a rumor that artifacting doesn't function over s-video, but this is certainly not the case on non-UAV systems.

None of my three XL Ataris with chroma pin hooked up for s-video, display artifacting when connected that way. I have six different CRTs, too. None of them are UAV either. I don't know what's going on with yours, but "people" are not "repeating rumors."

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1 hour ago, Panther said:

Ultima III and DROL on an 800.

 

Atari800-Ultima3.jpg

Atari800-DROL.jpg

That is interesting. Clearly there is some color leakage into the picture, though it isn't as intense and the luma isn't getting blended as it does with composite. It looks like it does on some of my CRTs when I don't disable composite while using S-video (which is very faint compared to yours, but has a little color like that and makes the picture less sharp) using Super Video 2.1 mod on XL. The luma leaks into the chroma from where it's combined to make the composite and permits some artifacting. So, maybe you could get it working on the UAV by using the composite output pin in place of the chroma pin from the UAV. That's the old "use composite as chroma" trick some people do with their XLs when they don't feel like going in to wire it up. It works well on many CRTs. Probably it would be better to blend it in to the chroma through a resistor rather than using the composite full-strength.

 

 

Edited by rmzalbar
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I get this same effect on my CRT, but I have to turn the Chroma control all the way up. I actually prefer it to using composite (for artifacting), because of it's a more subtle effect. The only thing about it is that the colors are different than your normal artifacted colors, and phase adjustment on my monitor is somewhat limited in altering the colors.

 

I use composite to get PAL blending on this same monitor (Project-M, etc.).

 

[Edit 1: This is on an 800XL, btw.]

 

[Edit 2: I should also note here, that I'm using an unshielded cable -- but otherwise good quality.] 

 

midnightmagic.thumb.png.61cdaf2ec2c43465e516fcbb1fa5b6cc.png

 

nightmission.thumb.png.8e926bc77e9c9a3f714c6802b5722484.png

 

ultima4.thumb.png.ad240db182a132a940b7c7db8b92c62d.png

 

Edited by MrFish
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Yes, granted that there is no fill between the columns, but it still looks much nicer than composite.  I've not made any adjustments to the monitor settings, or to the s-video to HDMI video converter.  The previous photos were on an LCD screen.  These are with a CRT (sorry, it's now daylight out, so quite a bit of glare from the window).

Atari800-CRT-UltimaIII.jpg

Atari800-CRT-SuperBunny.jpg

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As for colors, I get blue and green with composite, and I get magenta and green with s-video.  At least on the 800.  The video was not modified in any way on either of these 800s, but I've noticed the same effects over s-video on XE's and XL's that have had the missing signals added.

Edited by Panther
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30 minutes ago, Stephen said:

That's neat - I've never seen that before on s-video.  I wonder if I could make my display do that by using unshielded cable on purpose or even feeding composite into luma?

Every Atari I've seen does this, whether they're stock or modified with the Super Video 2.1 mod and using shielded cables.  CRTs or LCDs with converters, it doesn't matter, though of course overall quality varies.

 

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It doesn't happen if you use the optional composite video disable switch that's part of the Super Video 2.1 mod. At least, not on any of my three machines. If I leave the composite enabled, it does look like yours. This can only be from luma leaking back into chroma from where they are combined to make the composite. So if you want to cause it on purpose, just tie the two together with a large value resistor at the output of the UAV. You may need to experiment with resistor size.

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2 minutes ago, rmzalbar said:

It doesn't happen if you use the optional composite video disable switch that's part of the Super Video 2.1 mod. At least, not on any of my three machines. If I leave the composite enabled, it does look like yours. This can only be from luma leaking back into chroma from where they are combined to make the composite. So if you want to cause it on purpose, just tie the two together with a large value resistor at the output of the UAV. You may need to experiment with resistor size.

I didn't even know of a composite disable switch, but I will try that, thank you.  I've mostly always just used 800's with stock video, but I've had a few other systems hooked up over the years and where applicable they had the Super Video 2.1 mod, minus the switch that's not part of my documentation for it.

 

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On 4/4/2021 at 10:49 PM, rmzalbar said:

It doesn't happen if you use the optional composite video disable switch that's part of the Super Video 2.1 mod. At least, not on any of my three machines. If I leave the composite enabled, it does look like yours. This can only be from luma leaking back into chroma from where they are combined to make the composite. So if you want to cause it on purpose, just tie the two together with a large value resistor at the output of the UAV. You may need to experiment with resistor size.

While adding a resistor (around 470 ohms) across luma and chroma does add color to the artifact areas, it also bleeds into other pixels that shouldn't have color and adds a lot of noise, such as pixels showing up on a screen that's supposed to be blank.  The colors are also different.  Definitely not quite the same effect.

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4 hours ago, Panther said:

While adding a resistor (around 470 ohms) across luma and chroma does add color to the artifact areas, it also bleeds into other pixels that shouldn't have color and adds a lot of noise, such as pixels showing up on a screen that's supposed to be blank.  The colors are also different.  Definitely not quite the same effect.

Looks like after Super Video 2.1, the chroma and luma communicate through a three-component series of 75R, .001uf, 75R, combo. The capacitor and resistor form an RC filter and probably filters (I suppose) the luma out of the chroma. Worth a try?

 

This is from 800XL SV 2.1 (the pre-Super Video schematic also showed that series to combine the luma and chroma, but of course there's no chroma to pin 5.) Also note the composite-disable switch I mentioned in that string.

 

You likely won't have 75R resistors, but you can just use a single 150R and capacitor in series. The only reason for the order of the three is to set the composite output impedance, which is in the middle of the series, to 75 ohms.

 

sv21.thumb.png.892e3b32456b147fc6014c19bb3eb1d7.png

Edited by rmzalbar
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3 minutes ago, Panther said:

It's not my resistor collection that's lacking...searching for a 1nF capacitor.

PXL_20210407_005719488.thumb.jpg.2513e419140a1188defdb627d184acf9.jpg

I miss my local store "Philcap Electronics" - they had damn near anything in an NTE catalog hanging on a shelf somewhere, or under a counter in some dusty box.

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Funny enough, I found some "1000 pF" ceramic capacitors along with a 200 pack of 75 ohm resistors.  I was probably doing something with video back when I ordered those.  Unfortunately, using the two 75 ohm resistors with the 1 nF capacitor between them across the chroma and luma outputs I get the same results as just a resistor across them.  For example, I launch M.U.L.E. and instead of a plain yellow background there are darker stripes running down it.  In Exodus, there is color, but there's also coloring of the solid white areas too.

 

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2 hours ago, Stephen said:

I had no idea the artifacting colours were so different between RF and Composite.

See this post for colour artifact variations between the different models:

 

Edited by ratwell
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