Display issue on PAL VIC-20

[siccoyote]

Since I've been playing ab out with my vic-20 I have noticed that sometimes graphics can be difficult to see

I always thought this was just the way the hardware was, but just checking since the vice emulator doesn't replicate it.

Should some colours look like this?



or is there an issue with my vic chip?

Vice shows the same screen as this:



Also occurs with Cyan and Bright Green

[akator]

What kind of display are you using?

I've seen this same thing on many modern digital displays that upscale the analog video to higher resolutions. The built-in TV upscalers do a lot of dithering in the conversion. In my experience this dithering isn't in the source video but artifacts from the cheap converters built into TVS.

My solutions for multiple classic computers and game consoles:

1. Use S-Video. Most of the time this requires modifications to the original hardware. I personally average one video mod per system per year. It has taken me years for me to add S-Video to the several different systems I use on more regular basis.
2. Use a better third party upscaler/converter. The best are hundreds of dollars. I'm unwilling to pay that and instead use a $40 S-Video-to-HDMI converter. This converter isn't perfect but still does a much better job than the converter in the TV.

[siccoyote]

What kind of display are you using?

I've seen this same thing on many modern digital displays that upscale the analog video to higher resolutions.

What kind of lame ass noob do you take me for?



Thanks for the response but I think the answer is inside the vic-20 purely because it is limited to Red, Green, Cyan & Violet.

I thought about trying the RF but then realised it doesn't have one.

[mrr19121970]

You need to make the s-video mod. This known issue is due to chroma creep.

[siccoyote]

You need to make the s-video mod. This known issue is due to chroma creep.

Are you still selling those solderless mod cables?

Or do you have a diagram of it? I have seen the written instructions but a diagram would help.

(Though honestly I'm not a fan of s-video, I never seem to have much luck with it and it seems more essential in ntsc regions.)

[akator]

(Though honestly I'm not a fan of s-video, I never seem to have much luck with it and it seems more essential in ntsc regions.)

I felt the same way for a long time. It was only when the last of my CRTs died and I switched to digital displays that S-Video became a necessity.

[mrr19121970]

You need to make the s-video mod. This known issue is due to chroma creep.

Are you still selling those solderless mod cables?

Or do you have a diagram of it? I have seen the written instructions but a diagram would help.

(Though honestly I'm not a fan of s-video, I never seem to have much luck with it and it seems more essential in ntsc regions.)

it is very simple. Lift PIN2 of the VIC and add a 104 cap and 360ohm resistor in series. This is your chroma, luma is the old video out.

I don't sell the mods anymore.

[eslapion]

What kind of lame ass noob do you take me for?

...

Thanks for the response but I think the answer is inside the vic-20 purely because it is limited to Red, Green, Cyan & Violet.

I thought about trying the RF but then realised it doesn't have one.

Ha hum... all unmodified PAL VIC-20 will do that. It's caused by the way the color information is encoded on composite signals.

The suggested S-Video mod causes the Luma+ sync and chroma signals to become separate.

Of course, VICE will not simulate this effect.

No need for the 'lame ass noob" comment...

[siccoyote]

Ha hum... all unmodified PAL VIC-20 will do that. It's caused by the way the color information is encoded on composite signals.

The suggested S-Video mod causes the Luma+ sync and chroma signals to become separate.

Of course, VICE will not simulate this effect.

I knew you'd have the answer. So I can either have it authentic as it is now or do the mod for a cleaner image. At least I know is it's not a fault

[topcat]

I would also say it is 'normal' - but annoying.
I've seen similar effects called 'chroma crawl'.