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PostPosted: Tue Jul 24, 2018 9:49 am 
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I noticed the following effect in Nintaco and Mesen:

Image

I assume it's related to changing the palette mid-frame. Do any artifacts show up on a real NES?


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PostPosted: Tue Jul 24, 2018 9:54 am 
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No, they don't on mine.
Edit: I take this back, it does happen, just not on all resets. PPU alignment? See below.


Last edited by rainwarrior on Tue Jul 24, 2018 10:08 am, edited 1 time in total.

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PostPosted: Tue Jul 24, 2018 10:03 am 
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The effect is also present in RockNES. I can't seem to open the ROM in Nintendulator. The effect is not present in FCEUX or Nestopia.


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PostPosted: Tue Jul 24, 2018 10:05 am 
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My capture device can see a bit further into the hblank than my TV will show. Here's a slow motion view of that.


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PostPosted: Tue Jul 24, 2018 10:08 am 
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Actually! I take this all back.

The artifacts do occur on a real NES, just not every time. I think this is a PPU alignment thing where some resets it will have no artifact, and some resets you'll see a few pixels worth.

So... actually those emulators are fine. I can make it look like that on some resets.

(FCEUX is not a good thing to compare against for pixel perfect timings like that, even New PPU mode in FCEUX only has a granularity of 8 pixels per CPU synchronization.)


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PostPosted: Tue Jul 24, 2018 10:15 am 
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Hmm. That's really interesting. Resetting the emulators consistently produces the effect. But that could be a consequence what happens to the PPU upon reset within the emulator.


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PostPosted: Tue Jul 24, 2018 11:59 am 
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Emulators don't have different CPU/PPU alignments like the real console does.


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PostPosted: Tue Jul 24, 2018 2:34 pm 
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Last edited by Zepper on Wed Jul 25, 2018 3:33 pm, edited 1 time in total.

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PostPosted: Tue Jul 24, 2018 2:43 pm 
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Let you know what?


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PostPosted: Tue Jul 24, 2018 3:00 pm 
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Last edited by Zepper on Wed Jul 25, 2018 3:33 pm, edited 1 time in total.

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PostPosted: Tue Jul 24, 2018 5:15 pm 
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Oh, well I don't see any such artifacts on it, but I'm testing with PowerPak and that raster split is MMC3 IRQ based, so I couldn't tell you if this is an accurate emulation of that or not. (Indiana Jones on the other hand wasn't IRQ based, so I'd assume the PowerPak version is pretty close if not identical to the real cart.)


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PostPosted: Wed Jul 25, 2018 7:01 am 
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Zepper wrote:
Argh, ok, I'll spoil the same problem with Gauntlet II.


Those artifacts do not appear in other emulators.

rainwarrior wrote:
I'm testing with PowerPak


Can you post pics of the scanline and seam glitches in Super Mario Bros. 3 and Mega Man 3 ? I'm just curious what it's really supposed to look like :)

Also, does the scanline glitch appear on the NES Classic?


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PostPosted: Wed Jul 25, 2018 7:20 am 
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Quote:
the scanline glitch appear on the NES Classic?


I can confirm Megaman 3 (stage select) and SMB 3 have very obvious screen split glitches.

I don't own Gauntlet 2 nor Last Crusade.

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PostPosted: Wed Jul 25, 2018 7:24 am 
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dougeff wrote:
I can confirm Megaman 3 (stage select) and SMB 3 have very obvious screen split glitches.


Cool. I'm glad they did not patch the ROM or hack the emulator to conceal those issues.


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PostPosted: Wed Jul 25, 2018 7:48 am 
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You know, I misread your question.

I meant on an original NES.

I don't own NES classic.

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