The Mist FPGA computer - Classic home computers and consoles

Discussion in 'Retro & Arcade' started by philscomputerlab, Nov 5, 2015.

  1. philscomputerlab

    philscomputerlab Member

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    Some of you might know that I recently got a Mist FPGA computer. So I am documenting my journey, sharing what I found, how to set it all up, and of course with some YouTube videos along the way. No ads for Mist videos :)



    The Mist is a FPGA computer, which is a hardware programmable chip. Not to be confused with emulation, a FPGA replicates the entire circuit and chips in hardware. No "this task needs to wait for another task to finish", everything can happen in parallel.

    You can purchase the Mist FPGA computer from Germany, Poland and Spain:

    https://www.dragonbox.de/de/285-mist-fpga-konsolen.html

    http://www.lotharek.pl/

    http://amigastore.eu/en/318-mist-fpga-computer.html

    The Mist needs firmware, easily updated through the SD card reader.

    It also needs cores. What are cores? Every system, like the Amiga has its core, the Commodore C64 has its core, so does the NES or Atari St. The cores basically re-configure the FPGA.

    The Mist FPGA computer connects to standard peripherals such as VGA monitor, USB keyboard, mouse, gamepads. It has a headphone port for audio and is USB powered, a phone charger will do the trick.

    The latest firmware can be downloaded from here: https://github.com/mist-devel/mist-binaries/tree/master/firmware

    The cores can be downloaded from here: https://github.com/mist-devel/mist-binaries/tree/master/cores
     
  2. cavanor

    cavanor Member

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    This seems like a really good solution! I've spent most of my life repairing and tinkering with early 8 bit and 16 bit machines but no longer have the time or inclination to bother with seriously aging hardware (family and work life gets in the way). Definitely going to look into purchasing one. What's the outlook for long term support?
     
    Last edited: Nov 8, 2015
  3. OP
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    philscomputerlab

    philscomputerlab Member

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    My next video will be a "First time guide", so watch the space! As for long-term support, that's hard to say to be honest. But it seems FPGA developers aren't easy to come by.
     
  4. flugle

    flugle Member

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    I purchased one to do the same thing. I have a room full of Ataris and Amigas but this is doing a pretty good job so far of replacing them.
     
  5. OP
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    philscomputerlab

    philscomputerlab Member

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    Enjoy :D

    Featuring the Commodore 64 core.

     
  6. gdjacobs

    gdjacobs Member

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    Man, that game makes Contra look easy.

    As an aside to what you mentioned in the video, Genesis/Megadrive pads had a tendency to cook the CIA chip on original C64 units due to signaling conflicts between the pad and the keyboard. The solution was to install diodes to block the excess current. I don't know if the Mist includes a workaround for this issue.

    See the article in Commodore World #5 for more.
    [​IMG]
     
  7. OP
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    philscomputerlab

    philscomputerlab Member

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    That's good to know!
     
  8. OP
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    philscomputerlab

    philscomputerlab Member

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    Mist FPGA vs real Amiga vs Emulator Desert Dream Kefrens

    Time for an update!

    I have played around a lot more with the Mist FPGA computer. Various cores, tried games and demos and my initial excitement is fading somewhat I'm afraid :(

    I'm running into a lot of compatibility issues, not unlike what you experience with an early release of an emulator. The issue with FPGA computers is that there are very, very few FPGA programmers.

    So I did a video comparing the demo Desert Dream on the Mist compared to the real thing and an emulator.

    Pay attention to:

    - How it sounds
    - L and R channels
    - When the melon flies into the pyramid
    - When the rockets blow up the ship
    - Dot demo
    - General speed / length of running the demo

    All in all I'm a bit bummed out. I might make some "core review" type videos, showing how some demos don't work / pointing out differences.

    Anyway, go check it out and let me know what you think!

     
  9. Cannula

    Cannula Member

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    Well if you didn't label which was which I would of guess that the emulated version was the one on the left.
    The sound from the Mist is so tinny, I'm not sure if it's just the missing mids and bass but it doesn't have that warm FM syth sound I was expecting. It also renders too fast so quite a let down unfortunately.
    On a brighter note, the i740 and TnT arrived on Friday so I'll try and wade into the garage and sort out some ATi cards as well during the next week and let you know what I end up with.
     
  10. OP
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    philscomputerlab

    philscomputerlab Member

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    Yea it's only when you compare things side by side that you really notice the difference. When I played demos on the Mist the first time, they all seemed fine. HyRax1 helped me identify a few differences and once I had proper Amiga capture footage it became obvious that the Amiga FPGA core still has a long way to go...
     
  11. partybear

    partybear Member

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    Isn't the mist more expensive then just a real amiga 500?
     
  12. elvis

    elvis Old school old fool

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    It's important to realise that this will always be a "simulator", and never the real hardware. Much like "emulation" which simulates instruction cycles in software), even FPGAs won't match the real hardware for all the obscure features and functions that the original chips had.

    Even when you go back to old consoles, you'll find times when first party manufacturers released updated models of the same systems with slightly different chips, and they too suffered irregularities between their models.

    There was a real art to programming things back in the day. Without trying to sound all "get off my lawn", developers would often exploit features of the chips they worked on on such a way that would break on anything else. As much as software emulation and FPGA simulation does a great job, there's always going to be some obscure stuff that just won't work (either perfectly, or sometimes at all) on anything but the original hardware.

    The same goes for these hardware multi-in-one Megadrive/Genesis units you see on the market lately. Yeah, they've got legitimate Motorola 68K (or close successors of these) chips in them, but there's always a little bit of weirdness about the audio or video due to hardware differences. As above, even the Megadrive and Megadrive II had their differences, just due to a change to smaller/cheaper chips (despite the manufacturer claiming 100% compatibility). Such is life.
     
  13. zero_velocity

    zero_velocity Member

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    Oh man. I bought an altium FPGA development board while in uni. The software was brilliant, and what couldn't be successfully programmed could be mapped and drawn using logic gates :p mine is pretty mint despite not having used it for years, but I remember creating my own version of the old game 1942 (plane scroller) with my own designed graphics card!!! And the use of a drop in processor running my c code.

    I still have the development board at home in a cupboard:thumbdn:
     
  14. OP
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    philscomputerlab

    philscomputerlab Member

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    Especially demos can be tricky for the Mist. Games aren't too bad. I'm testing more games to get some sort of percentage figure in terms of compatibility. Games do work much better. Yes a few don't work, and a few more have glitches, but the vast majority work well.

    Stay tuned, I've got more videos in the pipeline, just a lack of time currently :upset:

    I'd also like to better compare the SID / Paula chips, I think many will find that interesting. The SID sounds quite good, the Paula has L and R swapped, but is also a lot brighter, which does sound quite nice, though not authentic.

    Someone mentioned input lag with emulators. I never quite noticed this, but that's also something I could compare. Although that might be a bit tricky to prove / measure.

    At works is a 17" CRT monitor, I really must take it home one day. Wondering what the Mist looks like on a CRT with scanlines turned on :)
     
    Last edited: Nov 26, 2015
  15. elvis

    elvis Old school old fool

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    Here's how we do it in the MAME community, particularly for input-sensitive games like arcade shoot-em-ups and fighting games:

    * Build a simple circuit with an LED inline for the button/keyboard input you care about. Can be as simple as an arcade button wired to an LED to a game controller, keyboard device like keywiz/ipac, or anything you like.

    * Take 60 FPS progressive scan (full frame, non-interlaced) video with your game in the background, and button/LED in the foreground

    * While filming, push the button and wait for the game to respond

    * Frame by frame, count the number of frames between the LED lighting up (proof of signal) and the game responding

    * Compare on original hardware and emulated systems.

    * Strongly recommended to use a CRT running at 60Hz to eliminate any variability in LCD displays.

    Here's an example that was used to prove lag between an original arcade board and various home ports of a popular fighting game:

     
    Last edited: Nov 28, 2015
  16. OP
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    philscomputerlab

    philscomputerlab Member

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    Nice, that gives me a starting point :)
     
  17. Grant

    Grant Member

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    Coming from an Amiga point of view, it'd be cool if you could "genlock" the camera to the sync signal going to the TV to eliminate the possible 1 frame of variance there.

    I'm not sure if it was done like that for that video, but I suspect for the hobbyist it'd probably take a complicated mess of breadboard and microcontrollers :)

    Alternatively you could try going for a much higher recording rate than 60Hz, the problem with that is you only get to see a portion of the CRT screen at a time.

    Unfortunately I was never into competitive fighting games, so while I do my best to get minimal input lag it's not something that keeps me up at night :)
     
  18. elvis

    elvis Old school old fool

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    Lag affects many genres of gaming. Anything that's "realtime" (requires you to react to some event on screen as it occurs) would be affected.

    Scrolling shoot 'em ups are another genre that are a personal favourite of mine, where even slight lag (whether your display, your input device, or both) can totally ruin an otherwise fun game. But the same would apply to driving games, jumping platformers, scrolling beat 'em ups, and dozens of other genres.

    It's not just a retro gaming problem either.

    http://www.displaylag.com/

    Modern games can suffer it on cheap and nasty televisions with high amounts of post processing or poor image drivers.

    I'd dare say short of turn based tactics or RPG genres, just about any other genre of gaming would suffer badly from lag problems.
     
  19. xga

    xga Member

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    Just out of interest, what camera are you using to record the set-up / plugging things into the Mist FPGA at the start of the video?
     
  20. OP
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    philscomputerlab

    philscomputerlab Member

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    I'm using a Nikon D3300 :)

    Been busy testing more C64 games. Putting together the video is a lot of work, so not sure when it will be finished...
     

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