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Finalizing the PCBs

Discussion in 'Pyra News' started by EvilDragon, Nov 27, 2017.

  1. TrashyMG

    TrashyMG Sarcasm Dispenser Staff Member

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    @Grench well I'd say you're on your own queue that differs from the rest of the pre-preorderers... I have a signed PCB that literally has the numbers 4 out of 200 on it.
     
  2. Grench

    Grench Forum Addict!

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    Yes - you at least have something physical to point to. At this point I have nothing but the entertainment of watching development.
     
  3. elwing

    elwing Rabbit Addict

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    That's a neat two month hobby!
     
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  4. ible

    ible Advanced Guard Tower

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    i actually do kinda feel bad for you. but our chunks of pcb aren't doing or proving much at the moment either :)
     
  5. lukey

    lukey Rare Species

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    @EvilDragon Will the EMMC Switch also be fixed with the redesign?
     
  6. EvilDragon

    EvilDragon Administrator Staff Member

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    There doesn't even exist a.switch that's faster, so the only way would be to sacrifice the MicroSD slot.
     
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  7. mati

    mati Still Fresh

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    So, whenever you want to wear these pants:
    [​IMG]
    you can switch to the transparent case. What a world to be alive.
     
    Djhg2000, Djoga'Ro, tarator and 2 others like this.
  8. directive0

    directive0 Very Active Member

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    More like this
     

    Attached Files:

  9. Grench

    Grench Forum Addict!

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    To my understanding:
    • The switch is doing it's job. I.e. the switch is NOT broken.
    • The existence of the switch has a very minimal negative impact on the performance of the 32GB eMMC. It shaves off the very top of the peaks of the performance curve and should not be noticeable.
    • The existence of the switch allows the presence of the internal microSDXC card slot - which has a current maximum capacity of 400GB - with lots of options at different price points along the way.

    What I'm less sure of:
    • The Pyra will be able to mount both the eMMC and the microSDXC during the same session and actively switch between them.
    • Activities performed that use both at once would have substantial performance impacts, but would still work.
     
  10. CommanderB

    CommanderB Member

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    As Nikolaus explained both can be used, but someone needs to write a driver for the switch

    Gesendet von meinem SM-N9005 mit Tapatalk
     
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  11. levi

    levi Still fresh, damnit!

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    Indeed, questions about dual-use performance and the ability to dual use it are largely software problems, and as mentioned in these boards recently, most work so far has been concerned with hardware revisions and simulations, and configuring the kernel to boot.
     
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  12. CommanderB

    CommanderB Member

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    I wonder how fast the switch could multiplex between the disks. The access requests for the other disk must be queued in the meantime somehow. There could be a great increase of access latency

    Gesendet von meinem SM-N9005 mit Tapatalk
     
  13. Grench

    Grench Forum Addict!

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    These are very round ballpark numbers presented for illustrative not quantitative thought.
    Assuming:
    The eMMC is rated at ~120MB/s average over sustained read/write.
    Assuming a current generation microSD card, it is rated at 75MB/s average over sustained read/write.

    first half - accounting for marketing: Nothing ever performs continuously at it's top rated speeds - and I'm after the worst case scenario. So, assume that half of the rated transfer rates are realistic and the rated values are peaks used for marketing.
    60MB/s and 37.5MB/s.

    second half - accounting for scenario: A plausible worst case scenario is going to be copying a file from eMMC to microSDXC while at the same time copying a file from microSDXC to the eMMC. It should fully saturate the bus and any caching. I'm going to make the brash assumption that this will half the performance of either media.
    30MB/s and 18.75MB/s

    third half - accounting for the multiplexer: Since both media are being controlled through the same bus, it is safe to assume that there will be about 50% of the 'normal' throughput to each type of media. Could be as low as 40% for switching overhead, but I like working in more round numbers and was aggressive in the first & second halfs.
    15MB/s and 9.375MB/s

    10-15MB/s oh my - well, not really.
    • That is still faster than most cards could work with the Pandora when it came out.
    • That is about the same speed as big computer HDDs were capable in Y2K. http://www.tomshardware.com/reviews/15-years-of-hard-drive-history,1368-7.html
    • This is an insanely overblown worst case scenario where the user is doing something known to be 'slow' - copying directly between these two mount points - which should be an incredibly rare need.
    So, I'm looking forward to someone creating a driver for this. I think it is going to be very very cool.
     
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  14. Da Dude

    Da Dude Member

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    great news ed!!!! I keep us posted.
    And some vids on youtube would be nice to show us the PCB, or a video making the first preorder console:)
     
  15. Wrath Of Khan

    Wrath Of Khan Soul soother...

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    I guess some mighty fine folks be wanting a transparent case but I' got a humdinger of a hankering fer a Dark red one myself.
     
  16. Silent-Hunter

    Silent-Hunter Advanced Member

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    Please don't do that.
     
  17. WizardStan

    WizardStan Mega GP Mania

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    Are bright pink cases still on the table? :p
     
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  18. levi

    levi Still fresh, damnit!

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    Are you offering to pay for a print run?
     
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  19. iArnold

    iArnold Member

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    Looking at a lot of comments I predict people ordering Pyra's with no case at all if they could get theirs sooner ;-)
     
  20. AndiTheBest

    AndiTheBest Active Member

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    Yeah, why waiting for a case when there is a 3D printer next to me that wants to print one with a wood filament ;)
     
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