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Documentation about the Vampire hardware

RTG Glitches

Marcus Gerards

Posts 58
16 Apr 2016 22:59


Hi all,

my system is: A600 Rev 1.5, WB 3.1, layers.library V45, no patches like BlazeWCP or FBlit.

I'm experiencing graphical glitches in RTG mode, like

- flickering lines,
- display goes black for up to a second (this seems to be the amplification of the "flickering lines", see theory below)

I tried several DVI->DIGITAL-VIDEO cables and I'm led to believe, that this might not be a hardware problem, since the glitches always occur while the display has to be updated under load, like:

- opening a drawer with many/large icons (happens with both icon.library V46 by Peter Keuneke and the original lib from OS3.1)
- opening a new window
- opening a new tab with Ibrowse
- scrolling in windows/listers

There may be a correlation between the amount of data that has to be modified in the frame buffer, the system load in general and the intensity of the image problems. Or not, since - and that's really strange - I cannot reproduce the issue by running the Intuition/Graphics benchmarks of SysSpeed.

Best regards,

Marcus



Claudio Guglielmotti
(Apollo Team Member)
Posts 185
17 Apr 2016 11:19


It seems that your monitor do not support the frequency.
If you increase or decrease a little the pixel clock with picasso96preferences, you should solve the problem.



Marcus Gerards

Posts 58
17 Apr 2016 15:50


Hi Claudio,

no, my Monitor does support the frequency - it's a Dell 2407 which even syncs to 49Hz. I will experiment with different values and set the frequency exactly to 60Hz.

But you got me thinking, since the phenonenon indeed looks like the display has to resync. Since this happens only while the computer is under load, maybe it's caused by minimal voltage drops which lead to temporal shifts of the video signal? I'm just guessing here.

I will investigate the issue further with a PicoPSU-based power supply once it arrives.


Marcus Gerards

Posts 58
21 Apr 2016 19:00


The issue seems to have mostly vanished, at least the total "blackouts" of the RTG signal. A small increase of the frequency in P96mode did the trick.

Thanks Claudio!


Nixus Minimax

Posts 416
22 Apr 2016 11:16


Marcus Gerards wrote:

The issue seems to have mostly vanished, at least the total "blackouts" of the RTG signal. A small increase of the frequency in P96mode did the trick.

Please report this solution in the right thread on a1k.org where you first reported the problem! Thanks!




Marcus Gerards

Posts 58
22 Apr 2016 17:04


Nixus Minimax wrote:

  Please report this solution in the right thread on a1k.org where you first reported the problem! Thanks!
 

Sure, done!


posts 6