Re: IMP DMA.
Posted: Wed Jun 22, 2022 10:01 pm
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Everything works. Screen still the same. Any ideas what's happening?
I would really take out the ossc and try something with simple RGB or VGA monitor if using high res .Cosmic Puppet wrote: ↑Thu Jun 23, 2022 2:16 am Everything works. Screen still the same. Any ideas what's happening?
You're not gonna believe this @exxos but the colour 'noise' just stopped. I call it noise because you can see horizontal bands moving.exxos wrote: ↑Thu Jun 23, 2022 2:19 amI would really take out the ossc and try something with simple RGB or VGA monitor if using high res .Cosmic Puppet wrote: ↑Thu Jun 23, 2022 2:16 am Everything works. Screen still the same. Any ideas what's happening?
So the odd colour thing only happens in emutos ? That's crazy.Cosmic Puppet wrote: ↑Thu Jun 23, 2022 2:36 am Anyway I had it set to white desktop on EmuTOS because that's always hidden my poor output, so then I awitched back to stock TOS 1.04 and the colour has vanished!
No, i meant having my white screen (available in EmuTOS) hides my NTSC output crappyness, so switched to TOS 1.04 to show the faults clearer and the colour had disappeared. So in 20 mins of running the computer since the new chip, it's cured! Will check again tomorrow (technically it is tomorrow) when I wake up.exxos wrote: ↑Thu Jun 23, 2022 2:47 amSo the odd colour thing only happens in emutos ? That's crazy.Cosmic Puppet wrote: ↑Thu Jun 23, 2022 2:36 am Anyway I had it set to white desktop on EmuTOS because that's always hidden my poor output, so then I awitched back to stock TOS 1.04 and the colour has vanished!
Okay.exxos wrote: ↑Thu Jun 23, 2022 2:58 am I think you should switch back to emutos and try that again as it seems you changed 2 things at once.
The DMA doesn't have any connection the the video. Aside from the data bus. But if that was corrupted your machine wouldn't boot.
DMA issues cause problems with the floppy and hard drive. It doesn't do anything else. IMP chips cause a lot more noise on the system than other brands. Its why Atari mentioned at some point that a system should only have 1 IMP chip otherwise the system goes nuts. Fixes were done by placing a diode in its power rail to make it behave better.
In anycase, I don't see how the DMA can cause problems with RGB output. If that was true, the IMP DMA would he worse.
Why NTSC ?Cosmic Puppet wrote: ↑Thu Jun 23, 2022 3:00 am No, i meant having my white screen (available in EmuTOS) hides my NTSC output crappyness, so switched to TOS 1.04 to show the faults clearer and the colour had disappeared. So in 20 mins of running the computer since the new chip, it's cured! Will check again tomorrow (technically it is tomorrow) when I wake up.