FCEUX with Dendy-mode

Discuss emulation of the Nintendo Entertainment System and Famicom.

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Bregalad
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Re: FCEUX with Dendy-mode

Post by Bregalad » Tue Apr 28, 2015 1:25 pm

Thank you very much!
It's impressive to see how it can play NTSC games with raster effects just fine at 50 Hz without any software changes. I wish Nintendo had been able to pull out something like that... The official PAL NES is a travesty.

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Re: FCEUX with Dendy-mode

Post by tokumaru » Tue Apr 28, 2015 1:46 pm

Bregalad wrote:It's impressive to see how it can play NTSC games with raster effects just fine at 50 Hz without any software changes.
Indeed. It's funny how some pirates found a better way to convert the system to PAL than Nintendo itself did.

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Re: FCEUX with Dendy-mode

Post by Dwedit » Wed Apr 29, 2015 6:47 am

Gotta play devil's advocate here... the official PAL NES has a much longer Vblank time for drawing tiles and stuff, and that gets signaled by NMI itself, so games don't need to do trickery to get notified about the large pre-vblank time.
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Re: FCEUX with Dendy-mode

Post by tokumaru » Wed Apr 29, 2015 8:01 am

Dwedit wrote:Gotta play devil's advocate here... the official PAL NES has a much longer Vblank time for drawing tiles and stuff
Yes, this is great for PAL-only stuff, but as I see it, the point of making the PAL console is creating a version of the hardware that works with TVs that are not NTSC, not create an upgraded version of the system with features that are incompatible with the original version. And the Dendy is much closer to the original NTSC NES.

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Re: FCEUX with Dendy-mode

Post by tepples » Wed Apr 29, 2015 9:53 am

Do you think Nintendo gave a flip about compatibility with other region software? Heck, Nintendo made two different CICs for PAL alone.

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Re: FCEUX with Dendy-mode

Post by tokumaru » Wed Apr 29, 2015 10:07 am

tepples wrote:Do you think Nintendo gave a flip about compatibility with other region software?
I don't think they made the timing so different on purpose, but I obviously can't say for sure. If they really wanted to screw up campatibility, they could do what they did to their RGB PPUs, which is scramble the palette and registers.

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Re: FCEUX with Dendy-mode

Post by Zepper » Wed Apr 29, 2015 11:24 am

I wonder about the real need of emulating PAL and Dendy. For example, is someone coding for Dendy? To play a PAL or Dendy game exactly the same way its NTSC version does sound a waste of time. Indeed, that's me of course.

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Re: FCEUX with Dendy-mode

Post by Eugene.S » Wed Apr 29, 2015 12:09 pm

For example, is someone coding for Dendy? To play a PAL or Dendy game exactly the same way its NTSC version does sound a waste of time.
Dendy was designed only for run actual NTSC-games at 50FPS.
We like slower gamespeed and music tempo. It's nostalgia: link1 \ link2
Absolutely useless to make exclusive software\games special for dendy-mode.

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Re: FCEUX with Dendy-mode

Post by Dwedit » Wed Apr 29, 2015 1:56 pm

Streemerz got written with NTSC/PAL/Dendy cross-compatibility in mind anyway. Try it in each mode, it will attempt to be the same game. Sound effects are one half-step too high in NTSC or Dendy mode, but besides that, music pitch, tempo and game speed are the same.
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Re: FCEUX with Dendy-mode

Post by Eugene.S » Wed Apr 29, 2015 2:22 pm

It's really nice, Dwedit.
I just want to say Zepper about "meaning of" Dendy-mode

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Re: FCEUX with Dendy-mode

Post by rainwarrior » Wed Apr 29, 2015 2:38 pm

Here's a few reasons, Zepper:

1. The Dendy was widespread, and well used. There are a lot of people who want to emulate these games the way they played them.
2. There is still a lot of Dendy hardware in use, so developers of new software would appreciate being able to test and debug for Dendy.
3. There are a few Dendy games (mostly bootleg hacks) that might be of interest to play.
4. There's not a lot of cost to implement Dendy mode in an existing NES emulator. The value vs cost ratio here is very good.

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Re: FCEUX with Dendy-mode

Post by Dwedit » Wed Apr 29, 2015 2:53 pm

The best part about implementing Dendy mode is that you can create "Overclocked" mode just by setting the frame rate back to 60 FPS. Games notorious for lagging (such as Mega Man 3 or Armadillo) would lag a lot less if they had the extra dummy scanlines in a frame.
Obviously you adjust the sound pitch and stuff so it's normal NTSC sound pitch again, and not 6/5 faster, this includes the DMC channel too. DMC IRQs will break because frames are longer than usual.
The only real artifacts you hear in Dendy mode is the APU frame counter being counted more times per frame than usual, so frequency sweeps are exaggerated.
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Re: FCEUX with Dendy-mode

Post by Eugene.S » Wed Apr 29, 2015 3:02 pm

rainwarrior wrote:There is still a lot of Dendy hardware in use ... The value vs cost ratio here is very good.
Really, a LOT. "Dendy-mode" is only euphonic name. A thousands of "NTSC/PAL hybrid" famiclones work on this timings.
They have different labels/names in CIS countries ("Dendy", "Lifa", "Kenga", "Subor", etc),
Eastern Europe (i know "Pegasus" in Poland) and Asian region ("MicroGenius" in Taiwan)

Many of them was based on bad and glitchy NOACs, like UM6561A, they fail some tests (like oam reading),
and have few game-compatibility issues (green tint, "prince of persia" glitches, swapped duty cycles, etc), but still keep "dendy" timings.
We do our tests only on good chips (first famiclones of early 90's have separate CPU and PPU, like Famicom).
They can pass many of nesdev tests and don't have nasty glitches, which NOACs have.

P.S. Sorry for my bad language. I'm not native english speaker.
Last edited by Eugene.S on Sun May 03, 2015 12:36 am, edited 2 times in total.

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Re: FCEUX with Dendy-mode

Post by feos » Fri May 01, 2015 11:30 am

Eugene.S wrote:TODO: fix NSF player, it's broken on Dendy-mode
Done in r3111.
https://sourceforge.net/p/fceultra/code/3111/log/

Is there something super important we're missing that could be added?
Dwedit wrote:The best part about implementing Dendy mode is that you can create "Overclocked" mode just by setting the frame rate back to 60 FPS. Games notorious for lagging (such as Mega Man 3 or Armadillo) would lag a lot less if they had the extra dummy scanlines in a frame.
Obviously you adjust the sound pitch and stuff so it's normal NTSC sound pitch again, and not 6/5 faster, this includes the DMC channel too. DMC IRQs will break because frames are longer than usual.
The only real artifacts you hear in Dendy mode is the APU frame counter being counted more times per frame than usual, so frequency sweeps are exaggerated.
Can you elaborate on how to force it? Was it already done in some emulator? In fceux, there are desired framerate, ppu loop scanlines, and cpu speed, that were affected by dendy mode, cpu speed being almost the same as ntsc though, so it alone affects nothing.

With target fps at 60, 290 scanlines sounded broken, sped up.
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Bregalad
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Re: FCEUX with Dendy-mode

Post by Bregalad » Sun May 17, 2015 6:19 am

I am not sure if this is related, but I've had problems for debugging my programs with this version of FCEUX. It mostly works, but sometimes it does not break when it should. I am not sure what causes this bug. I am breaking on reads from ROM, and sometimes it does not trigger, even though I am sure a particular address is read at some point.

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