Video driver thoughts

[exxos]

I don't think I have anything which could do that, I have pretty much zero software here other than GB6 :(

[sandord]

I don't think I have anything which could do that, I have pretty much zero software here other than GB6 :(

Here's a copy of CrackArt. There's a test.ca1 file in the root.

[exxos]

There is this test...

Second test is very interesting..

[exxos]

The plot thickens...

It seems to me it is the white border which is where things start to go wrong.. I have no idea why...

And I seriously cannot work out how to change colour in this package! I want neochome.. must have it somewhere...

IMG_3618.JPG

IMG_3619.JPG

IMG_3620.JPG

IMG_3621.JPG

[Icky]

So I just hooked up the RGB from the DAC board through the existing drivers on the mother board on D4, D5 & D6 on the RED connector side and then the point to the transistor.

Screen Shot 2018-11-29 at 21.02.38.png

On the red label side it was very dark but it did have the white border and there wasn't any purple waves.

On the transistor side it was displaying the same black screen with slight white on the TOS message.

One thing I noticed is the RED label side is also connected to BLANK on the MB.

[exxos]

One thing I noticed is the RED label side is also connected to BLANK on the MB.

Maybe that is a clue :shrug:

Can you post a image of what you are seeing ?

[sandord]

The plot thickens...
It seems to me it is the white border which is where things start to go wrong.. I have no idea why...

That is interesting. Surely the amount of white is a lot lower in the picture I posted.

And this explains why Magic Pockets ran fine, black border!

And I seriously cannot work out how to change colour in this package! I want neochome.. must have it somewhere...

While viewing the picture, press space and click on the first square on the left. Then put all 3 sliders on the right to their max.

[exxos]

It's definitely the border (had to change to noechrome sorry! ) As soon as any colour goes into the border things really start to mess up..

So maybe the blanking is needed something to happen with the monitor itself ?

@ Icky, I wonder if you can try the normal RGB circuit, but lift out the BLACKing didoes D1,D2,D3 ?



EDIT:

hmmm


In raster scan equipment, an image is built up by scanning an electron beam from left to right across a screen to produce a visible trace of one scan line, reducing the brightness of the beam to zero (horizontal blanking), moving it back as fast as possible to the left of the screen at a slightly lower position (the next scan line), restoring the brightness, and continuing until all the lines have been displayed and the beam is at the bottom right of the screen. Its intensity is then reduced to zero again (vertical blanking), and it is rapidly moved to the top left to start again, creating the next Film frame.

I could understand it with a CRT..... As may be electron be as it moves from right to left still producing some colour is why the BLANKing is done.. But I do not get why this would happen on a LCD.

[Icky]

@ Icky, I wonder if you can try the normal RGB circuit, but lift out the BLACKing didoes D1,D2,D3 ?

Just in the process of getting the video uploaded of the motherboard driver circuit in play.

Then I may get time to lift the blanking diodes - non-Atari duties are calling tonight.

[exxos]

I'm half thinking about bodge solution for this...

The only way I think we could implement blanking is to tie the analogue RGB inputs to 0V, and links the blanking signal to the analogue/digital select line on the DAC...

So the idea would be that when Blanking is active, it switches the RGB drivers to 0V....

This would basically emulate what the ST circuit is doing..