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MiSTer FPGA (computer/console/arcade hardware simulation)

Discussion in 'Retro & Arcade' started by elvis, Oct 14, 2018.

  1. OP
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    elvis

    elvis Old school old fool

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    I don't think there's any great rush. If it's a bit crazy now, wait for the dollar to sort itself out again.

    The whole project is open source, so it's not going anywhere. It's like MAME - it'll only get more comprehensive as time goes on.

    FPGA tech is also booming in many industries. It too will improve and come down in price as the years go on.
     
  2. Andrew_Wong

    Andrew_Wong Member

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    If you have a USB gamepad (or Arduino USB encoder) & keyboard, you don't need a IOboard, USBboard or even a powered hub at all.. I run my DE10 just like that with a simple USB hub.

    The 128MB RAM is half the price of the board - so if you want to go budget.. get by with 32MB. Good enough on a budget.

    MiSTer can be entry level, or the full 9 yards.
     
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  3. shredder

    shredder Member

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    Cheers Andrew.

    Actually :p ;) Old 32MB SDRAM's is also something I have in my junk pile, for free. Good luck plugging the bloody things into a Mister, but <pretend rant mode> omg you mean I have to re-pay Year 2000 prices for a special one!

    Or alternatively, I can desolder the RAM chips and put them onto a Mister compatible board that I custom poo out of my left nostril.
     
  4. MUTMAN

    MUTMAN Member

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    <pretend rant reply mode>
    no you have to pay 2020 prices for andrew to custom poo a pcb and solder the new chips on

    :D
     
  5. Andrew_Wong

    Andrew_Wong Member

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    Will have another go based on feedback.. also curved all the edges for 16mm T-Moulding to give it the clean look.

    For me, I'm going to weld up a tube steel frame for this.. also this is a prototype that's going into a cafe.. so I'm going to wall mount it so people can't carry it off !

    [​IMG]
     
    Last edited: Mar 8, 2020
  6. nimmers

    nimmers Member

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    Got my MiSTer going last night with just the USB hub and the RAM board.

    What is the current thinking on the I/O board? Do you guys think it's still worthwhile when direct video is now available?
     
  7. OP
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    elvis

    elvis Old school old fool

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    General consensus is "no".

    Longer answer:
    * Version 6.something IO board designs no longer includes analogue video, so it's going to vanish anyway
    * Existing IO boards were limited to 6 bit RGB (262K colours, versus 8 bit's 16M colours). Similar to the GertVGA666 on an RPi - a HDMI->RGB DAC gives you more colours.
    * Final visual quality will depend on your HDMI->RGB DAC, which means it can be inconsistent person to person if people get crappy encoders. There's a thread on the shmups forum that compares a few cheaper models, but sadly many manufacturers use the same cases on their devices, so it's hard to tell which one you have. And several have bad black crushing and white point variance which make it hard to guess at purchase time which is which.

    I think there are a few people now doing a better job of documenting which RGB DACs are the better ones. Being the colour pedant I am, it's still frustrating as nobody has objective measurements (either off an oscilloscope or from a colorimeter). Hopefully that gets better as time goes on.

    [edit] Audio is a similar story - a HDMI audio extractor can be had for very cheap. If you're extracting digital/optical/SPDIF type audio, then you're getting a purge digital signal so quality doesn't matter (just forward that on to your sound system/processor of choice). If you're using a DAC, even a $20 will produce excellent quality line-level sound that can be fed into any amp of your choice.
     
    Last edited: Mar 11, 2020
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  8. MUTMAN

    MUTMAN Member

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  9. OP
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    elvis

    elvis Old school old fool

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    I read somewhere (Atari forums? Twitter? Can't remember) that they were planning to phase it out in future releases.

    "They" being the upstream design in GitHub. I would assume people building them can keep doing whatever they want.
     
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  10. MUTMAN

    MUTMAN Member

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    OK, thanks.
    i think the board still has plenty of uses even without VGA.
    buttons and leds, fan, serial (snac), second uSD card, audio analog and spdif.
    i wouldnt argue for it as a must have, but it's not a waste of money depending on your use scenerios
     
  11. OP
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    elvis

    elvis Old school old fool

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    The IO board itself will stay. I think they're just removing the analogue video.

    I tell you what: before I keep shooting my mouth off, I'll try to track down the posts in question.
     
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  12. MUTMAN

    MUTMAN Member

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    hahaha. its all good, i believe you.
    i guess im just surprised is all.

    shame there's no way to get the full 8 bits from the onboard VGA
     
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  13. OP
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    elvis

    elvis Old school old fool

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    Same problem with the RPi: not enough GPIO pins for a full 8 bits per channel.

    You don't notice the limits in practice. Especially with old games that has far more limited palettes. But if they ever get N64/PS1 era stuff happening, it might show up a bit there.
     
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  14. nimmers

    nimmers Member

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    Tested out the Direct Video via the HDMI port with the cheap Jaycar adapter and I am blown away by how awesome it is.

    Are any of you guys using this too? I do have one question: I notice that as the system boots before the menu displays and for a second as you load a core you lose sync and the signal becomes a mess. Anyone know if this is just losing sync or if it's sending a signal that could damage my 15k gear?

    Also does anyone know if the RGB levels out of it are safe for consumer SCART gear and safe for AV1 on the OSSC?
     

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  15. OP
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    elvis

    elvis Old school old fool

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    Not on MiSTer (still using the IO board on mine, not the HDMI->analogue options), but I've been doing this stuff with Linux+MAME for 20 years, including digital to analogue conversions outside the system. At the end of the day a video signal is a video signal, so whether it comes from FPGA or emulation, it looks equally as great IMHO (I've fooled plenty of "PCB or death" types before with MAME setups). MiSTer for me is more about the fact that this is now achievable by anyone (no arcane video standards knowledge or Linux expertise needed), which is a good thing. And of course the whole low-lag thing, which goes without saying.

    Just your video system dropping sync. MiSTer will obey whatever is in the config file - so if your menu boots up to 15KHz, that's the only other mode it'll use other than the game/system you're selecting.

    For a CRT, syncing is a difficult thing to do quickly. First of all it needs to sample enough change to verify that it's a real change and not just a sync anomaly. Secondly there are electrical and mechanical changes that need to occur to change the mode. You'd probably be familiar with genuine arcade monitors that had manual vhold or hsync pots where you have to adjust a dial to get sync. On a broadcast monitor like a PVM, this change happens far more quickly, but it's still a physical change.

    Yes, MiSTer is exclusively video level output, whether it's RGB or YBpPr. No TTL/arcade levels in use.

    Conversely if you want to feed this into an arcade monitor, you'll need to amplify the signal appropriately (don't just over-drive the arcade CRT by jacking up the brightness).
     
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  16. nimmers

    nimmers Member

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    Yeah but before the menu loads I mean, kind of like how you need a custom BIOS on a GroovyMAME setup to stop it displaying the BIOS in 31k on bootup. It does look pretty ugly for a second just before the menu loads. I'll try and capture some footage.
     
  17. OP
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    elvis

    elvis Old school old fool

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    Ah that bit I'm not sure of. On my Analogue IO board it syncs instantly at boot, but I'm not sure what the HDMI out does by default before the MiSTer menu kicks in.

    I've got a HDMI to analogue converter at home, so I'll try to test it over the weekend to see. I bought myself a cheap and nasty oscilloscope too, so that might be a fun test to see if I can capture that.
     
  18. nimmers

    nimmers Member

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    Awesome. Cheers man!
     
  19. nimmers

    nimmers Member

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    elvis



    Seems like a pretty harsh transition between screens right?
     
  20. MUTMAN

    MUTMAN Member

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    i dont know if its bad, but it looks nasty.

    i dont see that on a vga via IO board
     
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