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Usb 2

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Name: jreeves54
Date: October 25, 2005 at 06:17:01 Pacific
OS: XP Pro w/svcpk2 udate
CPU/Ram: Intell/512
Comment:

The tech folks told me that if I ran a 1.1 USB device then all devices connected will be running at 1.1. Is this a true statement?



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Response Number 1
Name: XpUser
Date: October 25, 2005 at 06:18:16 Pacific
Reply:

True.

i_XpUser


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Response Number 2
Name: terii
Date: October 25, 2005 at 15:12:30 Pacific
Reply:

This taken from another site.


"You may have heard that USB 2.0 is "backward-compatible" with USB 1.0/1.1 (Full-Speed USB). While that's true, USB 1.1 is also forward-compatible with USB 2.0. Whenever a system has USB 2.0 ports, you'll find the "Enhanced" USB controller in Device Manager, but you will also find two other USB controllers. These two to mantain backward compatibility to USB 1.1 devices. Each USB 2.0 host actually has 3 chips onboard. The USB controller routes signals to the correct controller chip depending on how a device is recognized. Where a device is physically plugged in has no bearing on how it is routed. All ports on a USB 2.0 motherboard can host any USB devices at all as long as the system and devices are healthy.

The vast majority of USB 2.0 devices will work on older PCs and Macs. None should flat-out fail unless there are other issues with the system. Hi-Speed USB devices will revert to Full-Speed operation when connected this way. Understand that Hi-Speed is at least ten times faster than Full-Speed in actual operation, so the speed difference is quite noticeable - unless you have never experienced Hi-Speed, of course.

When it comes to USB hub compatibility between USB 2.0 and USB 1.1, here some facts:
A powered hub is always preferable to unpowered.
USB hub ports are not as capable or flexible as real PC ports so it's best not to expect the world of them.
USB 1.1 (obsolete) hubs will work fine on USB 2.0 ports, but they cannot utilize USB 2.0 capabilities. They will default to slower speeds.
Hi-Speed and Full/Low-Speed USB devices can coexist nicely on USB 2.0 hubs. Connecting such a hub to a USB 2.0 port is recommended.
USB 2.0 hubs can be used on older USB 1.1 computers.
Although it is said that you can "cascade" up to 4 hubs, problems may start to arise after two hubs, it's best to minimize hub usage if possible.
Many USB devices don't work well on hubs. Cameras, scanners and especially USB drives are known to have problems with hub connectivity.
Remember that "active USB extensions" are really just one-port hubs.
As you can see, there are very few issues (if any) to be concerned about when mixing USB types. If the system and devices are healthy, it should be a "no-brainer" to connect any USB device - provided that you follow manufacturer?s instructions.

By William DeVercelly


Last edited by billyd on 01-20-2005 at 05:19 PM"

It pretty well says it all.



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