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There's a "Channel 3/4" button on the back of Tano Dragons, what happens when you press it? Does one NTSC channel give a better display than the other?

zephyr wrote:You can test the PMODE 3 screen colours by loading a game such as the attached Chuckie Egg.

Sorry, Steve. I have been with my time full doing a composite video mod for my Color64. Originally his image was crap, now it's much better:

Before the Mod: https://picasaweb.google.com/1093456998 ... 0386044450

After the Mod: https://picasaweb.google.com/1093456998 ... 1336536530

I will grab the Dragon to do those tests and let you know.

Alastair wrote:There's a "Channel 3/4" button on the back of Tano Dragons, what happens when you press it? Does one NTSC channel give a better display than the other?

No effect, because I'm not using the RF output. I have done a cable with a DIN5 plug to connect to the Monitor port of the Dragon.
Curiously, the image on the RF output is not so saturated as the Composite video.

Daniel

Dantyr wrote:

Alastair wrote:There's a "Channel 3/4" button on the back of Tano Dragons, what happens when you press it? Does one NTSC channel give a better display than the other?

No effect, because I'm not using the RF output. I have done a cable with a DIN5 plug to connect to the Monitor port of the Dragon.
Curiously, the image on the RF output is not so saturated as the Composite video.

Daniel

Living in a PAL country it's a little difficult for me to talk about artifacting because it's something I've never witnessed outside of emulation. However I thought that artifacting was an NTSC only phenomena, are you saying that you can also get artifacting with composite video output?

It's still NTSC, just baseband - before modulation onto an RF carrier. It's at this point artifacting happens, as it's such a simple relationship between the "dot clock" and the NTSC colour carrier frequency.

But I've no real idea about the saturated colours - amplitude of colour signal too high in relation to the luma? There's a "DC balance" trim pot on the motherboard you can mess with (VR1), which adjusts where black is, and so everything else in relation to that. Might help, and I don't know of anything else to adjust.

sixxie wrote:It's still NTSC, just baseband - before modulation onto an RF carrier. It's at this point artifacting happens, as it's such a simple relationship between the "dot clock" and the NTSC colour carrier frequency.

But I've no real idea about the saturated colours - amplitude of colour signal too high in relation to the luma? There's a "DC balance" trim pot on the motherboard you can mess with (VR1), which adjusts where black is, and so everything else in relation to that. Might help, and I don't know of anything else to adjust.

On the Color64 I had the same saturated colors as on the Dragon. I solved putting two trim pots in pulldown on the color signal lines (B-Y and R-Y) between MC6847 and MC1372. That solved the issue, but on the Dragon I will need to see how the MC6847 is connected on the LM1889 (that is the modulator) to see if it's possible. The only trimpot on Tano (beside 6847) is for brightness, I think.

There is any place I could grab the schematics of the Tano Dragon ?

Daniel

Dantyr wrote: There is any place I could grab the schematics of the Tano Dragon ?

The only schematics available are for the UK Dragon 64. They can be downloaded from http://www.dragondata.co.uk/

zephyr wrote:The only schematics available are for the UK Dragon 64. They can be downloaded from http://www.dragondata.co.uk/

Thanks!
Looking the schematics I noticed that the British Dragon 64 is pretty diferent from the Tano on the video output.
I will tap on the color signal lines that go to the LM1889 modulator to see if I can reduce the saturation somehow.

Daniel