USB GDrom Thread

Discussion in 'Sega Dreamcast Development and Research' started by nonosto, Jun 13, 2015.

  1. Greg2600

    Greg2600 Resolute Member

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    Wait a second....what does he need these for? Are you telling me he is REUSING legacy DC parts in this thing???
     
  2. megavolt85

    megavolt85 Peppy Member

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    WTF!!!!!!!!!!!
    After such news I stopped respecting MNEMO as developer.
     
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  3. Damn-Deal-Done

    Damn-Deal-Done Spirited Member

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    No idea. I'm not an electronics guy. Just reporting the news I saw.
     
  4. Braintrash

    Braintrash Peppy Member

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    I have never been a fan of his work, but he really set up an all-time low with that...
     
  5. takeshi385

    takeshi385 Mojarra Frita Bandit

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    I thought someone had gotten ahold of these connectors in bulk. WTH is going on.
     
  6. -=FamilyGuy=-

    -=FamilyGuy=- Site Supporter 2049

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    He can't possibly only want the connectors? He sells his ODE for like 200$. Assuming cost is 60$ for the sake of argument even if it is probably higher, this would mean that the connector is worth 7.5$ to him? (well more since I underestimated his cost)

    It just doesn't add up.

    Is he reusing GDRom controller chips?
     
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  7. Anthony817

    Anthony817 Familiar Face

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    Yeah, he is gutting the boards for the chipsets on them which are a finite resource, so that is the only reason he needs these. You can't exactly get brand new controller chips for GDRom boards.

    I was quite taken aback by it too when I read about it the other day. I guess it makes sense because this device replaces both the actual disc drive AND GDRom controller right? I mean controller is even in the name. Top fucking kek.

    http://3do-renovation.ru/USB-GDROM_Controller.htm

    Edit: Guess it is these chips. I can't get a clearer view than that.

    [​IMG]

    Double Edit: Only other semi-clear picture II could find of the controller board without taking apart my own systems was this which was modded.

    [​IMG]

    I can see the Toshiba chip at least looks similar, but the ARM chip is new. Maybe he uses the actual connector as well as the other smaller chips too?
     
    Last edited: Jul 13, 2018
  8. fry76

    fry76 Member

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    I guess he needs it mostly for the MOLEX connector.
     
    Last edited: Jul 13, 2018
  9. -=FamilyGuy=-

    -=FamilyGuy=- Site Supporter 2049

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    He's basically giving a 25$ rebate per board. It's that valuable to him? Didn't @Bad_Ad84 or Deunan found a compatible Molex part?

    It would really be weird if he's using genuine Sega chips. If so, maybe he'd need a reverse engineering 101 class from Deunan...
     
  10. fry76

    fry76 Member

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    Maybe he needs urgently some connectors, because there is no stock any more of this old Molex, so the only way to get new ones it's to make them via a factory in China who will copy it, with a hight MOQ (Minimum Order Quantity).

    So, 25$ for a connector it's a lot, but he need it for his coming orders, i guess.

    unlike GDemu, his board it's much cheaper to build, like 2 times.
     
    Last edited: Jul 13, 2018
  11. -=FamilyGuy=-

    -=FamilyGuy=- Site Supporter 2049

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    12.5$, I though it was 8 instead of 16 boards somehow. But still, this is a very very weird situation.
     
  12. Greg2600

    Greg2600 Resolute Member

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    Who cares if they copy a connector???? This MNEMO is just a tool. I literally have not seen anyone as unprofessional (outside Mike Kennedy) in retro gaming in the last 10 years.
     
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  13. Atolm

    Atolm Spirited Member

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    Is this the same connector that Stone Age Gamer sourced for him a while ago before the falling out? Leaving SAG with a stockpile of them?
     
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  14. fry76

    fry76 Member

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    no one cares, but need time and $$
     
  15. Anthony817

    Anthony817 Familiar Face

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    Now I am almost certain it is that, but the Toshiba chip looks awfully similar to the one on the Sega boards. I googled the part number on them and came up with no source still making those either, so he must be also needing chips from them too.
     
  16. Bad_Ad84

    Bad_Ad84 The Tick

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    Yeah, when all the SAG drama kicked off, I found the part no issue and provided the link. Could have changed in the last few years though.
     
  17. fry76

    fry76 Member

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    Just for "info" I do have a gdrom PCB with out any Sega chip. I guess it's early one.
     

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  18. keropi

    keropi Familiar Face

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    I don't really see what's so damnable about what MNEMO requests, why are you people so worked up about this?
    He wants boards and is willing to make a discount for them, I used to know several people that could easily harvest 20~30 dead drives , strip the boards and send them over - nowdays I think they rest in recycle heaven , is that better?

    You can make a strong case about his business decisions though :D
     
  19. Zeigren

    Zeigren Spirited Member

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    The molex connectors are easy enough to buy brand new, so he doesn't necessarily need to salvage those.
    This has been talked about before in the "Let's make GDROM Emulation happen...." thread, but I'll go over it in more detail here.

    So the USB-GDROM uses an ST ARM microcontroller (some Cortex-M3 one) in conjunction with a Toshiba TC9466FA CD-ROM decoder with 1Mb buffer RAM. This chip is what actually interacts with the Dreamcast, so he doesn't need to emulate the communication to the Dreamcast at all. He just needs to emulate the disc side communication to the TC9466FA with the microcontroller, aka emulate a Toshiba TC9450AF. But because he does it this way he's reliant on being able to source that Toshiba IC which probably stopped being produced over 10 years ago.

    This chip is not what is actually used in any Dreamcast (as far as I know), but it is very similar. The GDROM drive with Toshiba chips uses what I believe is a TC9410BFA, marked as a SEGA 313-5640 (IC 5). This does not have an internal buffer, so instead the GDROM drive uses an external 128KB buffer. The equivalent part on the Yamaha drives is the Yamaha XU916A0.

    The OTI-9220 is indeed from an earlier Dreamcast, it is also present in Katana drives. It pretty much does all the CD-ROM stuff in a single chip.

    "Oak Technology’s OTI-9220 is a 4-in-1 single-chip CD-ROM solution containing an IDE/ATAPI interface, CD-ROM decoder, DRAM buffer, digital signal processor (DSP), digital servo control, and digital-to-analog converter (DAC)."

    I imagine they switched to Toshiba/Yamaha because they are Japanese companies.
     
    Last edited: Jul 15, 2018
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  20. Friend of Sonic

    Friend of Sonic Spirited Member

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    I'm having a strange issue with my USB adapter-- I've had it lose connection during one gameplay connection where the game crashes, and then other times I've had the menu go extremely slow, and stop working, along with other misc crashes. It seems as though every time if I remove the USB cable from the DC and reseat it, it's fine for a while. I thought maybe the HDD was going bad but I was able to copy the entire contents of it. I will do a formal test and try another HDD on it to see if it is the HDD, but the fact that unplugging it, and plugging it back in, along with the somewhat looseness of the port, makes me wonder if it's related to that.

    Anyone ever encounter this?
     

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