PAL chroma merging?

[thefox]

If red and green are swapped, blue might still be the same, though.

Yeah that's it, red and green are swapped, blue is the same.

A photo from a TV screen showing a version of blargg's full palette demo hacked for PAL:

pal-nes-emphasis.png

(From top to bottom 000, 001, 010, 011, 100, 101, 110, 111)

[lidnariq]

Is this the same problem the Dendy has?

[thefox]

Is this the same problem the Dendy has?

Didn't Dendy have a problem that it showed green emphasis or whatever when all of the emphasis bits were on? If so, that doesn't happen on PAL NES. "All bits on" makes the palette darker as on NTSC (as evidenced by the photo and well, there being several PAL region games that use the screen darkening trick).

[Drag]

The Dendy generates a PAL signal, so it's likely that it is indeed the same issue. Don't forget that some clones don't get the APU duty cycles right, so this could be something that happens on clones and not the genuine thing, just like that.

[tepples]

The Dendy generates a PAL signal

But are the changes made to the PPU by Steepler's ASIC supplier to make a PAL signal the same changes that Nintendo made, or were different choices made by different engineers with different priorities? I know the Dendy CPU is different from the PAL NES (/15 instead of /16), and the Dendy PPU's timing is different (vblank at 291 instead of 241), for maximum compatibility with Famicom software.

[Drag]

But are the changes made to the PPU by Steepler's ASIC supplier to make a PAL signal the same changes that Nintendo made, or were different choices made by different engineers with different priorities?

Dunno. How do you even clone something like this, anyway? It could be that official PAL Famicoms have the red/green bits swapped and since that's what got cloned, that's what shows up on Dendys. Or, it could be that they don't and the cloner got things mixed up somehow, or swapped it to avoid patent infringements or something goofy like that.

[Quietust]

If red and green are swapped, blue might still be the same, though.

Yeah that's it, red and green are swapped, blue is the same.

A photo from a TV screen showing a version of blargg's full palette demo hacked for PAL:

pal-nes-emphasis.png

(From top to bottom 000, 001, 010, 011, 100, 101, 110, 111)

Which version of the palette test ROM is that? Because I've got 2 versions which have different layouts and different emphasis orders:

1. "version 2", where each color section is upside-down ($30/$20/$10/$00 top-to-bottom) and emphasis is ordered White,Blue,Magenta,Red,Yellow,Green,Cyan,Black (000,100,101,001,011,010,110,111)
2. "optimized version", where each color section is right-side-up ($00/$10/$20/$30 top-to-bottom) and emphasis is ordered White,Red,Green,Yellow,Blue,Magenta,Cyan,Black (000,001,010,011,100,101,110,111)

Your image seems to be using color layout #1 but emphasis layout #2, which is a bit confusing.

[thefox]

Which version of the palette test ROM is that? Because I've got 2 versions which have different layouts and different emphasis orders:

1. "version 2", where each color section is upside-down ($30/$20/$10/$00 top-to-bottom) and emphasis is ordered White,Blue,Magenta,Red,Yellow,Green,Cyan,Black (000,100,101,001,011,010,110,111)
2. "optimized version", where each color section is right-side-up ($00/$10/$20/$30 top-to-bottom) and emphasis is ordered White,Red,Green,Yellow,Blue,Magenta,Cyan,Black (000,001,010,011,100,101,110,111)

Your image seems to be using color layout #1 but emphasis layout #2, which is a bit confusing.

Here's the ROM:

full-palette-pal.nes

NOTE: This ROM is just a quick hack from the original. It's not optimized in any way to minimize flicker/wobble. Also it doesn't display the full palette (some colors are cut out from the right).

The source is based on the download from http://wiki.nesdev.com/w/index.php/Full_palette_demo

[thefox]

Yeah I tested Kid Icarus now as well, and it's very noticeable there right from the beginning.

I'm surprised I haven't seen this mentioned anywhere before.

Another game where this is very noticeable is Elite. Those single pixel wide wireframe figures on a black background showcase the alternating even/odd scanline color perfectly.

[Eugene.S]

Here is "Full NES Palette Viewer - Optimized Version by Blargg (PD)" photo captured on custom-made Dendy (UA6538 PPU, Famicom AV PCB):

[thefox]

Here is "Full NES Palette Viewer - Optimized Version by Blargg (PD)" photo captured ...

It'd be better to use the forum's attachment feature for images.

[Eugene.S]

I've attached images

[lidnariq]

Eugene, any chance you could take a picture of thefox's or my chroma merging tests? I'm curious whether the Dendy PPU's as peculiar as the 2C07.

[Eugene.S]

Ok, I will try. Is this tests work on punes dendy mode timings?

[lidnariq]

There's no raster effects, so it should work fine regardless of 2C02/2C07/Dendy.