Jump to content
IGNORED

How does 320 mode look on a CRT?


PacManPlus

Recommended Posts

As many of you know, 320 mode is my go-to mode for arcade ports, as the pixels are a very close ratio to actual arcade games of the era.  That got me thinking about why Atari/GCC didn't use this mode more often for their ports (aside from the color limitations)?

 

I seem to remember about 15 years ago I had a CRT, and 320 mode looked absolutely horrible on it due to color shifting.  The darker the color, the worse it got.  I remember thinking that may have been the reason they didn't use it...  Or maybe it was just the TV I had.

 

Does anyone still have a CRT that they use for the 7800?  How does 320 mode look on it?

Link to comment
Share on other sites

Yes. I run a high-quality RF cable from the 7800 to a fancy tuner, then composite to a Sony PVM. In other words: in the ballpark of as good as it gets for an RF-CRT setup. 160-mode games and 2600 games look great.

 

320 has a lot of color fringing. I wouldn't say horrible, but it is definitely an issue. I believe it would be better with an S-Video mod — but I'm not certain about that.

 

Want me to look at anything in particular?

  • Like 1
Link to comment
Share on other sites

CRT utilizing composite and the 320 mode games: Pac-Man Collection 40th Anniversary Edition, Berzerk (Frenzy), Dungeon Stalker, all look great.  If there is something specific you would like tested or any particular capture you need provided, more than happy to provide it; nonetheless, below are some examples. 

 

Please note that colors and the black background are richer and 'truer' in person.  Berzerk, for instance, the walls are a 'true-blue' color not the washed out 'white-blue' shown below with a bloom effect that is much more subdued.  There is also a moire effect that is not visible live when viewed on the actual display, causing some loss of clarity and sharpness.   These are all 'quick and dirty' with some lighting noise from the room behind the display as well:

 

PAC10.png.aa7db0e66a6894a4c2d40a8772b5b44b.pngMSPAC10.png.985eb2a21ac3d224709a9ea317ec1317.png

 

BERZERK10.png.74a8e9f800e21ce3a2f69d472d639588.pngFRENZYTITLE10.png.2318b2e8927fa7dff9e62d9dd0cb8972.png

 

DS310.png.310a571e699ad85f45a920a3ddea8dcc.pngDS210.png.e04ce1ffa008d338c35a60fa4a1493e1.pngDS110.png.7343c39d9800baff7456bd08caa2b5cb.png

 

 

 

 

 

  • Like 3
Link to comment
Share on other sites

The final result depends on the whole setup, including the quality and equipment of the CRT TV / monitor. Starting with the good news (and also looking to the future), what you will see on the screen will have excellent quality under real hardware, FPGA, consoles on a chip (or emulation) with S-Video, RGB, VGA or HDMI output.

 

However under real hardware, RF output and composite video output _without a comb filter_ will produce some artifacts. Generally, CRT monitors and most CRT TV's from the early 2000's have good comb filters, and when it is absent it is still possible to have an external comb filter (used ones have affordable prices). Digressing among the alternatives, it is also possible to have an external demodulator followed by composite to s-video (Y / C) converter (in case we want to preserve the original RF output without modifying the console) or even a demodulator with HDMI output, if you're lucky enough to own one of those rare CRTs with HDMI output.

 

Finally, when the circumstances allow it, it is also possible to prevent the formation of artifacts by making some targeted changes to the graphics, in this case the aesthetic result will be hybrid between the 160 mode and the 320 mode.

 

I add a couple of links for more information:

http://7800.8bitdev.org/index.php/Atari_7800_Color_Documentation#Color_Artifacting

 

 

1525876162_7800artifacts...thumb.PNG.09f1533cb84bd834873ace9af2b59176.PNG

 

 

 

403119439_7800artifacts.thumb.PNG.94233438a1c1ec92863a368f47188ade.PNG

 

 

 

 

 

 

577561457_7800artifacts..thumb.PNG.7450f029af7bb8bb63830742a1923562.PNG

 

 

 

 

Edited by Defender_2600
  • Like 3
Link to comment
Share on other sites

6 hours ago, Pat Brady said:

Yes. I run a high-quality RF cable from the 7800 to a fancy tuner, then composite to a Sony PVM. In other words: in the ballpark of as good as it gets for an RF-CRT setup. 160-mode games and 2600 games look great.

 

320 has a lot of color fringing. I wouldn't say horrible, but it is definitely an issue. I believe it would be better with an S-Video mod — but I'm not certain about that.

 

 

An expensive solution (without modifying the console), but maybe since you are using a Sony PVM...

http://www.burstelectronics.com/c2yc.htm

 

Also, among the various solutions tested, I got a (small) improvement with this:
https://www.amazon.com/Monster-CSVC-1-Integrator-Discontinued-Manufacturer/dp/B00004Y2ZK

 

Edited by Defender_2600
  • Like 2
  • Thanks 1
Link to comment
Share on other sites

8 hours ago, PacManPlus said:

As many of you know, 320 mode is my go-to mode for arcade ports, as the pixels are a very close ratio to actual arcade games of the era.  That got me thinking about why Atari/GCC didn't use this mode more often for their ports (aside from the color limitations)?

 

I seem to remember about 15 years ago I had a CRT, and 320 mode looked absolutely horrible on it due to color shifting.  The darker the color, the worse it got.  I remember thinking that may have been the reason they didn't use it...  Or maybe it was just the TV I had.

 

Does anyone still have a CRT that they use for the 7800?  How does 320 mode look on it?

It can look amazing if you've got a well tweaked setup, certainly on an NTSC machine. But there's lots of issues when it comes to the picture and the 7800... On a PAL machine, as stock, the picture is dreadful. It has inherent faults the NTSC machine doesn't when it comes to interference from both the colourburst clock and shared chroma lines. To add insult to injury the PAL Maria adds a heat related colour rolling 'feature'. Which can be bad or not depending on machine.


The NTSC machine fairs better in that the clock and chroma are WAY better done here. It starts out with a good chance of a decent picture. There is a timing offset that's common on NTSC machines however that causes the chroma to be slightly out of sync with the luma resulting in colour fringing. You can address that by running the chroma signal through a series of gates to slow it down. It's not exact, but you can get very close, but it's possible to make the picture much better by doing so. It's surprising just how much that offset buggers up the NTSC picture in my opinion. All this you'd not really see on RF, because it's so bad and you expect it to be blurry... On the NTSC machine the Maria again has the old colour drifting problem. Again down to heat.

 

So the long and the short of it is that a normally modded NTSC 7800 into a domestic CRT will look pretty good, but not perfect by any means. A heavily modded 7800 into a professional monitor can look nigh on RGB in output. Mine is tweaked the the nth degree, colour shifted and runs S-Video into a Sony PVM. The picture is utterly stunning. I'll go try and take some pictures, but it's not easy to photograph in that room.

 

EDIT: Well I took loads of pics and they were just all blurry or reflecting things, these came out the best. Interestingly these are the three games that show up the colour shift the most when it happens (really showes up on blue lines).

 

PacMan.thumb.jpg.ddafb448ff3e7c81fb4fa3d73c4bfd7f.jpg

 

DungStalk.thumb.jpg.a0c87c180dc4e8a552b4201917a3a855.jpg

Berzerk.thumb.jpg.2dc32ec9312b6c5dcbbe9349260f602c.jpg

Edited by juansolo
Added pics
  • Like 4
Link to comment
Share on other sites

1 hour ago, juansolo said:

All this you'd not really see on RF, because it's so bad and you expect it to be blurry...

I've always liked the idea of preserving the original hardware with RF output, so one of my NTSC 7800 was connected to a Sony PVM 20 inch via a professional demodulator, RF to S-Video with comb filter. In all fairness, the result was quite spectacular, it didn't look like it was displaying RGB quality but definitely worthy S-Video quality. In my experience, the quality of the demodulator and comb filter can make an important difference.

  • Like 3
Link to comment
Share on other sites

2 hours ago, juansolo said:

EDIT: Well I took loads of pics and they were just all blurry or reflecting things, these came out the best. Interestingly these are the three games that show up the colour shift the most when it happens (really showes up on blue lines).

 

In truth, it is the position of the pixel that determines the artifact and the blue color can hide it quite well as the artifact is about the same color, as you can see in the example made by Trebor:

 

 

 

artifact.thumb.PNG.d2c4b9798e4adc557346f06020fb2d21.PNG

  • Like 3
Link to comment
Share on other sites

For me, assorted colour artifacts are more of a feature than a bug (though that also depends on a particular mood I'm in). The things I would consider real problems on the so-called "inferior" signals (RF/Composite) would be cable interference and noise, and the dot crawl. The former is always a nuisance, the latter can sometimes be also considered an "effect' though (eg a rolling sky or sea). But, sometimes even snowy RF can be amusing, when I feel like being 100% authentic.

 

When I first started collecting real hardware I was also into modding and dragging output as close to the "ideal' RGB as possible, but later gave up on that and now prefer unmodified OG HW. If I want pure RGB, I have MiSTer going into a high end consumer Trinitron, which is probably as good as it gets, but I don't always feel like using it because it's a bit...sterile, at least when compared to the wild, original look.

  • Like 4
Link to comment
Share on other sites

Thank you all for your replies.

 

I didn't needs anything specifically checked (although I *was* curious about PMC:40th, as back when I did the singular 320 mode pac games, those are the ones that looked horrible on my screen.  Well, those and Space Invaders, which is why I used very light colors on it)

 

So maybe that's why 320 mode wasn't really used much back in the day?  Too much variation on how the picture looks depending on your setup - from great to unplayable.

 

It really was just a curiosity question for me.

 

Thank you again!

Bob

Edited by PacManPlus
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...