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Thread: USB 2 and 3

  1. #1
    USB 2 and 3
    Quilica's Avatar
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    USB 2 and 3
    I have a Mac Pro 2006 1,1 with USB 2 according to specs. Everything else I have is USB 3. I am wondering if cables for the two different generations will work together. I bought a USB hub before I considered this and the hub is USB 3. It has a micro B plug on one end (connects to hub) with the USB connector on the other end. I'm bringing the Mac Pro back into the sunlight after all these years so am not up to speed on all the cables.

  2. #2
    USB 2 and 3
    ferrarr's Avatar
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    Most USB devices are backwards compatible. You would need to check the hubs specs. However, the USB 3.0 devices will still only operate at the USB 2.0 speeds.
    -- Bob --
    Please backup. Everything has a life cycle, unexpected and warning free. Nothing will last as long as you want it to.

  3. #3
    USB 2 and 3
    Quilica's Avatar
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    Good to know. Thank you.

  4. #4
    USB 2 and 3
    krs's Avatar
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    This is a good overview/explanation of the USB type connectors.
    USB Connector and Cable Type Guide | Newnex

  5. #5
    USB 2 and 3
    Raz0rEdge's Avatar
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    While the USB spec/standard is backward compatible. That is, a USB 3.0 device can be plugged into a USB 2.0 port and operate a 2.0 speeds and plugged into a 1.1 port and operate at 1.1 speeds. In actuality, you will find that USB 3.0 devices will only work with USB 3.0 ports and 2.0 devices will work with 2.0 and 1.1 ports. The margin on these devices is just too thin for them to buy the USB chip that is backward compatible, it's just not worth it to them.

    I've bought a number of USB flash drives recently that won't work on my printer which only has a USB 1.1 port. Same thing with one of my cars which has a USB 2.0 port. I had to go and find a very old USB drive that was 1.1 (64 MB) and 2.0 (1 GB) to connect.

    So your mileage will vary greatly.
    --
    Regards
    ...Ashwin


  6. #6
    USB 2 and 3
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    I still have a couple of D-I-Y 2.5" USB 2.0 HD enclosures, that work on all my USB 3.0 computers. They were all purchased, ~2009 or before.
    -- Bob --
    Please backup. Everything has a life cycle, unexpected and warning free. Nothing will last as long as you want it to.

  7. #7
    USB 2 and 3
    krs's Avatar
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    Quote Originally Posted by Raz0rEdge View Post
    In actuality, you will find that USB 3.0 devices will only work with USB 3.0 ports and 2.0 devices will work with 2.0 and 1.1 ports.
    Would a USB 3.0 device working or not working in a USB 2.0 port not depend on the specific manufacturer?
    I sure as heck expect a USB 3.0 flash drive to work as "USB 2.0" if it says so right on the package

    Kingston USB_3.0_800.jpg

  8. #8
    USB 2 and 3
    Quilica's Avatar
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    I've spent the morning getting as far as I can as to hooking up. The 3.0 USB hub I purchased now has a wired Mac keyboard USB 2.0 hooked up but, as yet, I have not given it the "smoke test." (That's an old Navy electronic tech's term.) I now have to open the package of wire ties and get the spaghetti in some semblance of order. I'll take a photo and post it if I don't burn the house down first. It feels like Christmas when I had to assemble the kid's bikes.

  9. #9
    USB 2 and 3
    krs's Avatar
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    Quote Originally Posted by ferrarr View Post
    I still have a couple of D-I-Y 2.5" USB 2.0 HD enclosures, that work on all my USB 3.0 computers. They were all purchased, ~2009 or before.
    I read Ashwin's comments the other way around - that a USB 3.0 device would not work in a USB 2.0 port
    In actuality, you will find that USB 3.0 devices will only work with USB 3.0 ports and 2.0 devices will work with 2.0 and 1.1 ports. The margin on these devices is just too thin for them to buy the USB chip that is backward compatible

  10. #10
    USB 2 and 3
    Raz0rEdge's Avatar
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    Quote Originally Posted by krs View Post
    Would a USB 3.0 device working or not working in a USB 2.0 port not depend on the specific manufacturer?
    I sure as heck expect a USB 3.0 flash drive to work as "USB 2.0" if it says so right on the package

    Kingston USB_3.0_800.jpg
    In this case since the device specifically calls out 3.1, 3.0 and 2.0, you should be OK with that device on those ports. But interestingly, these should all be compatible with 1.1 (since the spec is backward compatible), but you might find that it doesn't work with the 1.1 port. Additionally, if they hadn't called out 2.0 on the material, it likely would only work on 3.1 and 3.0 ports, that was the point I was trying to make.
    --
    Regards
    ...Ashwin


  11. #11
    USB 2 and 3
    krs's Avatar
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    @Ashwin - I must say your post is an eye opener for me.
    I always thought that any USB 3.0 device is backwards compatible with a USB 2.0 port except for the speed. That is certainly the way USB 3.0 is marketed generally.
    But I just bought a SanDisk 128 GB flash drive and it states nothing about USB 2.0 compatibility on the package.
    Actually, just reading the super small print on the back now (print is not quite 1 millimeter high), it actually states "USB 3.0 port required"
    As they say - you learn something new every day.

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