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PostPosted: Sun Apr 01, 2018 10:07 am 
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I would like to propose additions to the NES 2.0 format for your esteemed consideration. Reasons:
  1. I have counted at least ten games now that require Dendy timing and are incompatible with RP2C02 and RP2C07 timing. "Incompatible" in one case means the game (西天取经 II - Journey to the West) crashes at the beginning of a boss battle.
  2. Several mutually-incompatible Famiclones need to be distinguished from each other.
  3. The Vs. Dual System is not supported.
  4. Additional protection types on the Vs. Unisystem need to be specified.

Edit: Updated version here.


Last edited by NewRisingSun on Thu Jul 05, 2018 11:22 am, edited 15 times in total.

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PostPosted: Sun Apr 01, 2018 10:24 am 
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viewtopic.php?f=3&t=2090&start=75#p180674


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PostPosted: Sun Apr 01, 2018 10:30 am 
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By request, reposting my brief summary of what dendy is, originally posted here:
http://tasvideos.org/forum/viewtopic.ph ... 169#467169


Here is a map of countries and video signal standards used in them. Note how huge the PAL/SECAM zone is. Compare it to which countries the NES/Famicom console was sold in.
en.wikipedia.org/wiki/History_of_the_Nintendo_Entertainment_System#Going_international_(1984-1987)

You will notice that most of the world has never seen official NES/Famicom release. That led to pirated clones of this console being sold all over Eurasia in early 90's.

A Taiwanese hardware manufacturer, TXC Corporation, developed a device compatible with Famicom and with PAL/SECAM signal at the same time. They called it Micro Genius, and it was sold under different names all over Eurasia, where no PAL NES or Famicom was sold.

In Russia it was sold as Dendy, and by that name it was recognized by the emulation scene, because it was Russian enthusiasts (one of them you can see right above this post) who studied how Dendy operates and how it differs from official consoles, and they convinced several emulator authors to add Dendy mode, in addition to NTSC and PAL. In most emulators it's called Dendy mode, but in fact it was a Hybrid mode technically speaking: NTSC games working on a PAL console, and Dendy wasn't the console this mode originated from, Micro Genius was.

Most of the time pirates were simply ripping off NES and Famicom games, occasionally adding cheats to them, sometimes breaking them by this. Some games were developed for PAL Famiclones from scratch, but it's not easy to find them (TXC themselves developed some of them). And finally, there were ports of other consoles games to this platform.

One of the developer teams doing such ports was Hummer Team. There is a HUGE article about its history, in Russian, called Hummer Team: все, что вы хотели знать о главных пиратах.

Right now I have no info on whether such bootleg games were sold outside Micro Genius area. Since they were perfectly compatible with Famicom, there is a high chance they were sold in Japan. But carts such games were released on are incompatible with NES, and PAL NES timings were incompatible with those of Micro Genius. Considering that even official PAL NES wasn't very popular in Europe, bootleg games had vanishingly little chance to ever exist on the PAL NES market.

This leaves us with a conclusion that bootleg games made by Asian developers for Micro Genius market were basically only spread within that market, with little possible exception of appearing in official NES/Famicom area.


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PostPosted: Sun Apr 01, 2018 10:38 am 
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Eugene.S wrote:
viewtopic.php?f=3&t=2090&start=75#p180674
Specifying what is "preferred" is somewhat subjective. I would rather specify what a game needs.

And if an emulator author can be bothered to support the expanded NES 2.0 field, they can also be bothered to make the simple changes needed for "Dendy"-like timing, so additional values for emulators that only support the expanded field but not "Dendy"-like timing seem wasteful.
feos wrote:
By request, reposting my brief summary of what dendy is, originally posted here:
I will gladly rename "Dendy timing" to something else if you prefer. What I mean is a 50 Hz PPU with 312 scanlines that starts the NMI at scanline 291. Games that "need" Dendy timing use screen splits timed according to an 21-scanlines-long NMI period, but have an NMI handler that sometimes takes more than 262 lines and thus will freeze on a regular NTSC console because the next NMI is raised when the previous has not finished yet, for example when massaging level data.


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PostPosted: Sun Apr 01, 2018 10:44 am 
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Thank you feos. I've added the info about "Micro Genius by TXC" being the original name to the wiki's article about regional console subtypes.


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PostPosted: Sun Apr 01, 2018 11:05 am 
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NTSC Famiclones:
Code:
UMC UA6527 (CPU)
UMC UA6528 (PPU)

PAL Famiclones ("dendy-timing")
Code:
MicroGenius MG-P-501 (CPU)
MicroGenius MG-P-502 (PPU)
UMC UA6527P (CPU)
UMC UA6538 (PPU)
TA-03NP1 6527P (CPU)
TA-02NP 6538 (PPU)
HA6527P (CPU)
HA6538 (PPU)
UMC UM6561 series (NOAC)

And lots of them...
BTW, i don't know any famiclone which have Real PAL NES timing.


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PostPosted: Sun Apr 01, 2018 1:26 pm 
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feos wrote:

Which very misleadingly classifies Brazil as PAL, while PAL-M actually uses NTSC timing. Because this happened to my country in that map, I don't know how accurate it is for all other countries.

BTW, I find it really amusing how pirates found a better way to make a PAL version of the NES/Famicom than Nintendo itself. I don't know if Nintendo intentionally made the PAL NES more different from the original than needed, as a form of region-locking, but judging by the many poor conversions that were made for the European market, I'm pretty sure that developers would've benefitted from better compatibility between the two systems.


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PostPosted: Sun Apr 01, 2018 1:41 pm 
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Argentina (50Hz, 3.6MHz PAL) and Brazil (60Hz, 3.6MHz PAL) got their own special PPUs from UMC. Programs that run on Brazil's standard are definitely closer to 2C02 than UA6538.

Comparisons of geography are misleading. Better comparisons would involve cartograms by population or ideally (and unavailable) by total numbers of relevant consoles (i.e. with a cart slot) sold.

P.S. my page on the wiki: nesdevwiki:User:Lidnariq/Known PPU revisions


Last edited by lidnariq on Sun Apr 01, 2018 6:01 pm, edited 2 times in total.

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PostPosted: Sun Apr 01, 2018 1:41 pm 
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Yes, PAL-M has the best of two worlds. The colors of PAL and the frame rate of NTSC. It's not PAL.

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PostPosted: Sun Apr 01, 2018 3:22 pm 
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Except we were constantly converting from NTSC to PAL-M: video game consoles had transcoding circuits inside, rental VHS tapes were all NTSC,which our VCRs had to convert to PAL-M, so we didn't really see the supposed benefits of PAL-M.


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PostPosted: Sun Apr 01, 2018 10:04 pm 
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PAL-M and N still use the near 3.5MHz color subcarrier so there's no improvement in color resolution over NTSC. It can only be transmitted longer over air without color getting messed up.

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PostPosted: Sun Apr 01, 2018 10:23 pm 
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If they're anything like European PAL, they also have the 2 line comb filter for chroma as part of the spec. This lets TVs possibly try to recover more horizontal chroma bandwidth, seeing as the comb filter already does much of the separation in the vertical axis.


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PostPosted: Mon Apr 02, 2018 1:48 am 
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I hate to interrupt, but this thread is supposed to be about discussing NES 2.0 changes, not talking trivia about television systems in Latin America. :wink:


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PostPosted: Mon Apr 02, 2018 2:17 am 
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NewRisingSun wrote:
I have counted at least ten games now that require Dendy timing and are incompatible with RP2C02 and RP2C07 timing. "Incompatible" in one case means the game (西天取经 II - Journey to the West) crashes at the beginning of a boss battle.

Journey to the West was developed by TXC corp, so it confirms the theory.


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PostPosted: Mon Apr 02, 2018 6:32 am 
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NewRisingSun wrote:
Changes to byte 12: TV System
[...]
Meaning of Byte 13 if byte 7 bits 0-1==3: Extended console type
In hindsight, having a single byte for PPU would have been nicer. Sadly, I suspect it's not an option.

NewRisingSun wrote:
7 - Vs. Dual System with normal inputs
8 - Vs. Dual System with reversed inputs
I'm a little uncomfortable with stuffing two separate CPU's and two separate PPU's PRG and CHR ROM into a single .NES image. Unlike the other variations, this situation requires emulating two screens as well.

In hindsight, I guess this is not too dissimilar from the Playchoice, but the secondary screen there is static and not relevant for gameplay.

How would Raid on Bungeling Bay be packed?


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