A NES Motherboard For The Open Source Generation

As the original hardware from the golden era of 8-bit computer gaming becomes a bit long in the tooth, keeping it alive has become something of a concern for enthusiasts. There have been a succession of remanufactured parts for many of the major platforms of the day, and now thanks to [Redherring32] it’s the turn of the NES console.

The OpenTendo is a completely open-source replacement for an original front-loading Nintendo Entertainment System motherboard, using both original or after-market Nintendo CPU and PPU chips, and other still readily available components. It doesn’t incorporate Nintendo’s CIC lockout chip — Drew Littrell wrote a great article on how that security feature worked — but if you really need the authenticity there is also the NullCIC project that can simulate that component.

It’s an interesting exercise in reverse engineering as well as a chance to look at the NES at the chip level. Also for Nintendo-heads, it provides all the component footprints and schematic items in KiCAD format. Will many be built? Given that the NES was the best-selling console of its time there should be no shortage of originals to be found, but that in no way invalidates the effort put into this project. There will be NES consoles somewhere running for decades to come because of work such as this, simply remember that you don’t need to blow in the slot to make it work!

36 thoughts on “A NES Motherboard For The Open Source Generation

    1. None, because the patents expired in the ’00s so Nintendo can’t really do anything about it as long as they stay away from their trademarks (and in the latter case they can always change names as needed rather than shut down the project).

      1. Copyrights haven’t yet expired, for a company they run for 90 years. You’ve still got a while to wait before you can assert that Super Mario Bros. is in the public domain, but the hardware to run it on is free for anyone to make.

        1. You’re talking about a game, one that they constantly release so as to renew their copyright each time they do. This isn’t about that, but rather the actual hardware patents. The NES hardware patents are expired and that’s why hundreds of clone consoles legally exist today.

      1. In Germany we have a saying ” two idiots one thought” which has the same meaning as “great minds think alike”
        I also downloaded everything including release files etc….just in case.

        1. “two idiots, one thought” is great and works well in English. “Great Minds think alike” has a few optional additional clauses to complete the sentence, and to nail down the fact that it said tongue in cheek: “…and fools seldom differ” is one option, or just “…and so do we.”

    2. This isn’t IP, it’s hardware. Patents run out in 20 years. After that anyone can reverse engineer your technology. It’s the reason they can’t (and don’t) go after emulators and clones of older devices.

    3. They would have a hard time with that.
      This doesn’t appear to infringe any trademarks, and a design isn’t covered by copyright.

      That only leaves patents. There’s a reason Nintendo went after 8bitDO for their SNES controllers, but hasn’t gone after a single clone console manufacturer.
      They re-filed a trademark on the design of the controller when the snes mini happened.
      However, that only covers the appearance. Hence the visual redesign of 8bitDO’s controllers that still keep the overall shape.

      Patents though… Those last only 25 years.
      So anything from 1995 or earlier is fair game.

      The only thing they could protect is say, an OS ROM (because that counts as software that can be copyrighted. But the NES doesn’t have one of those…

    4. The chances are very slim, the patents on the system expired over 10yrs ago, and “NES” is no longer a trademark as of 2016 (In fact the same goes for “SNES” as they cancelled both trademarks the same day) and I didn’t even use any of their official schematics etc as reference either, so the project doesn’t use any of their IP, nor do they own any of my reference materials.
      So OpenTendo is legally clean.

  1. Pretty cool. Good to see things like this being made, much like the SixtyClone (C64 motherboard). Wonder if someone will make something like the C64 Reloaded, but for the NES, replacing any particularly troublesome components and onboard memory with modern components and making it more energy efficient.

  2. I think it’s amazing that someone took the time out of their busy life, to sit down and make a mirror copy almost, if not exactly, like the original. I thank you Red!

  3. What IP?

    Patents expire after 20 years. So-called “Famiclones” have proliferated for years, everything from cheap SoC units like the FC Twin, Retro Duo, and RetroN 3 to higher-end FPGA-based systems like the retroUSB AVS and the Analgoue Nt. Have you noticed Nintendo hasn’t shut down any of those projects? That’s because it has no legal basis to do so. Because its patents on the NES have long since expired.

    Nintendo still owns copyrights for every game it’s ever published. And it owns trademarks to its brands, characters, logos, etc. And it still owns any patents it’s filed in the past 20 years. But any patent older than that has expired.

    Nintendo can, and does, order takedowns of ROM sites, fan games, and other works that infringe its copyrights and trademarks. But it no longer has any claim to the internals of the NES. Or the SNES, N64, Game Boy, Virtual Boy, or Game Boy Color. It has no legal standing to shut down replicas of those systems. It can stop people from redistributing Super Mario Bros., but not from making hardware that will run it.

  4. Red, and plans on doing the same for the top loader? I have one with a million bodge wires because previous owner destroyed ppu traces trying to desolder for an RGB mod, I’d love to have a clean pcb replacement. Anyways awesome work!

  5. Inhibit

    Yaaaas!!! We need a more modern ppu. HDMI out. However Try to keep most of the magic in the cartridge if you will so current game releases would be enhanced but still play able on vanilla machine… Super Gameboyish perhaps.. just put a new machine in cartridge…??…

    Blorb.. working on that. Blinky Light win is a brilliant design imho.. I’ve basically cloned the idea but need to adjust my cart slot models and figure out how to break down smaller for easy 3d printing.

    Red… Beautiful work. I tip my hat.

  6. Outside border of OEM NES was exposed metal to provide electrical contact to the RF shielding. Putting resist there kinda defeats the purpose.

    OEM NES had some minor problems with the voltage supplies coupling into the PPU video signal, and all the PPU stuff coupling into audio. The toploading NES had much worse related problems. It’d be better to move parts and provide better mixed-signal layout and routing.

    1. I love this idea. Not new but I dont know if anyone ever got CPU and PPU “clones”(but 1/1 operationally working). replacing PPU with other hardware seems to be popular.

      1. There’s an FPGA PPU (https://github.com/RetroEmbedded/UniversalPPU), however the CPU has yet to get the same treatment.
        There’s also the well known (Some might say infamous) bootleg CPU and PPU, UA6527 and UA6528 respectively. aside from those there haven’t really been many clones of either sadly.
        Though in my opinion an FPGA CPU is also very feasible given that it’s been well implemented in MiSTER, that said it definitely wouldn’t be an economical/cheap clone, but it *would* be worth it for the research/hardware aspect of it.

  7. wow, I remember “hacking” this problem back in,…maybe….the late 80’s? After the reset, one chip (the master on the NES?) sent out a 4 bit pulse representing the numbers 0 to 15. This number represented the time delay which the other chip (slave in cart?) must analyze and wait until responding. The delay units were related to the clock pulses. If the responding chip did respond at the proper clock pulse, the reset did not occur and the game would play.

    Had a lot of offers for that info!!

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