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PostPosted: Sun Feb 19, 2017 7:41 pm 
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That's how I'd understand that language. The 6502's masks were new in 1975-1978, so a derivative work (the 2A03) designed in 1982ish wouldn't be relevant... BUT because the "commercial exploitation" of the NES postdates the mask protection law, it "should" have had mask exclusivity until 1993ish or so.

I am not a lawyer, so take that with an enormous grain of salt.


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PostPosted: Sun Feb 19, 2017 8:45 pm 
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zeroone wrote:
I still don't understand why Commodore didn't sue the hell out of Ricoh and Nintendo

According this "Iwata Asks" interview Ricoh had a license:

Quote:
But Ricoh wanted us to use the 6502, which they had the license for.


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PostPosted: Sun Feb 19, 2017 9:30 pm 
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cyc wrote:
According this "Iwata Asks" interview Ricoh had a license:


Then, that begs the question, why did they have to disable decimal mode?


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PostPosted: Sun Feb 19, 2017 9:32 pm 
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If they did have a license, it might have been for a reduced functionality subset so as not to compete with the first-party 6502.

On the other hand, there's an anecdote in On the Edge that MOS was surprised to discover that the 2A03's CPU core was a 6502 with the patented parts scratched off.


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PostPosted: Mon Feb 20, 2017 11:25 pm 
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Real question i want to know:
"Who first engineered hybrid NTSC/PAL ("Dendy timings") famiclones,
and which CPU and PPU models was really first on this timings..."


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PostPosted: Sat Feb 25, 2017 8:14 am 
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Eugene.S wrote:
Real question i want to know:
"Who first engineered hybrid NTSC/PAL ("Dendy timings") famiclones,
and which CPU and PPU models was really first on this timings..."

Real good question!!

How could they have cloned the chips??
Microfilming/photographing it??
Was this kind of technology available back in the day??
Reverse engeneering?
How would they got the duty cycles wrong on the APU??


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PostPosted: Sun Feb 26, 2017 3:20 am 
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My simple guess is that Chinese engineers made their own CPU and PPU trying to match the original ones by reverse engineering them, but they made mistakes with things like rectangle duty cycle. The chips used in Dendy was made for PAL countries, but they included some characteristics of the NTSC chips to maintain compatibility with NTSC games, as most games in these markets were either bootlegs of licensed Japanese games, or unlicensed Taiwanese originals.


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PostPosted: Sun Feb 26, 2017 9:35 am 
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Would this be cost effective??
How much time a group of experienced engineers could do it back in the day?
Maybe the "plans" (I don't know exactly how to say that) for the chip or part of them have leaked. Who knows??


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PostPosted: Sun Feb 26, 2017 12:49 pm 
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Wouldn't they probably have gotten many more things wrong than just the audio duty cycles if they were doing this through reverse engineering?


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PostPosted: Sun Feb 26, 2017 2:46 pm 
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I'd presume they're using a direct copy of the 6502 mask, so probably the CPU by itself is pretty accurate? (Do famiclones typically have a decimal mode?)

It's plausible that there's lots of inaccuracies with the APU/PPU implementations that just haven't been thoroughly investigated. We've spent a lot of time testing dark areas of the authentic NES, but nowhere close to that attention has been spent on clones. That's a whole lot of leeway to do things differently that wouldn't make a noticeable difference in all existing games, or even just almost all.

E.g. when I started looking closely at the MMC5, I couldn't find any documentation that precisely described how its length counter was different than the 2A03's, or whether any sweep functionality existed, etc. No existing games used it so it didn't matter unless you actually wanted to go looking for it. Almost all emulators don't have a correct implementation of this stuff, but it completely doesn't matter because there's no ROMs that rely on it.


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PostPosted: Sun Feb 26, 2017 3:08 pm 
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Yeah I think they got more things than the duty cycle wrong.
I'm no expert on Famiclonese but I also heard that there are clones with a working decimal mode. There are even clones (by Waixing I think) that only plays its own cartridges, and clones that are more personal computers than game consoles, but are using Famiclone hardware because it's cheap to make and it has tons of compatible games and programs available already.


Fisher wrote:
Would this be cost effective??
How much time a group of experienced engineers could do it back in the day?

Cheaper than designing your own system. Plus it already had games.
China had and still has lots of engineers. There are technical universities founded only for the reason of mass producing more engineers to quickly build things like railroads.

I mean even Japanese Ricoh ripped off the MOS 6502. Unless they really had a legal licence, but I doubt that considering they chopped off the decimal circuitry.


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PostPosted: Sun Feb 26, 2017 3:51 pm 
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Pokun wrote:
Unless [Ricoh] really had a legal licence, but I doubt that considering they chopped off the decimal circuitry.
The decimal circuitry may have been tied to per-unit royalties, while the license may have (foolishly, in hindsight) not considered that Ricoh could have elided the patent-protected portion of the circuitry.


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PostPosted: Sun Feb 26, 2017 4:16 pm 
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What kind of tests should I try?
Maybe I should start with these test ROMs??
I don't promise much, since all I have is a flash ROM and a UxROM socketed board.


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PostPosted: Mon Apr 16, 2018 1:08 am 
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Eugene.S wrote:
Real question i want to know:
"Who first engineered hybrid NTSC/PAL ("Dendy timings") famiclones,
and which CPU and PPU models was really first on this timings..."


Interesting document:
viewtopic.php?f=9&t=17257#p216827
http://www.austlii.edu.au/cgi-bin/sinod ... intendo%20

Quote:
After discussions held with UMC we are able to provide to
you the following information as requested by you. The
picture processing unit was designed by UMC and its original
purpose was to produce and generate a video output signal
for Pal system TV's. The PPU in question was designed in
1987 and manufactured commercially a short time later. As
you are aware through your technical training it is more
difficult to copy an original layout than to produce an
original integrated circuit. The PPU was designed with aid
of CAD tools using existing functional blocks available in
its library. There are many types of PPU's available on the
market and we would be surprised if not all but most carry
some kind of resemblance due to their design characteristics
and their end result in terms of functionality. This
similarity can be noticed with a large number of integrated
circuits available on the market today.
The two devices cannot be directly replaced for each other.
Hence the two devices are not functionally compatible. The
UA-6538 can process the cartridges designed for NTSC TV
systems whereas the RP2007-0 cannot do this due to its
inferior design. The interrupt signal timing between these
two devices are quite different from each other. This can
be tested by measuring on the TV game module (pin 19 on
PPU). The DRAM refresh circuits on the RP2007-0 for data
retention are not necessary for UA 6538, and please note
most importantly that the control timing and data retention
method for these two devices are totally different


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PostPosted: Mon Apr 16, 2018 7:02 am 
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Back then no CPU was copyrightable. You could not copyright a CPU, or an instruction set. See the Z80 and 8080 or the NEC V20. However the way MOS did the BCD conversion was unique and patented. It gave MOS an edge. So while Ricoh had the rights to make 6502s, you only needed the license so you could reproduce the BCD circuit. So Ricoh said if you don't take the BCD then we don't have to pay the royalty to MOS and you save money on the chip. I also feel that it would have partly been some spite of Yamauchi - hes not a man to let a slight go unanswered.

I feel a big error on the NES was zero ROM. If they had some boot software on the device ( as they corrected on the GB) that would have eventually become protected allowing them to go after clones. Of cause you can still clean room etc but it makes it a lot harder. The Commodore VIC-20/C64 and C128 are anomalies - there are NO clones. The most successful 8bit computers and not a single clone. I mean if you are going to waste your time cloning an Apple II, a ZX Spectrum etc you would think they would put the effort into the most popular computers of all time. The did make clones of the 1541 disk drive however.


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