Re: question on USB 1.1 and 2.0 together
- From: "JohnO" <johno@!NOOSPAM!heathkit.com>
- Date: Thu, 20 Nov 2008 16:48:29 -0500
Keep in mind that *all* of today's devices and ports are USB 2.0. What we
really mean is Low speed, full speed, and Hi-Speed. Even Intel is attempting
to change its language this way, but the message isn't making it to their
tech support people.
A low-speed keyboard and hi-speed flash on the same port MAY slow that port
to low-speed. The port will detect what's out there, and switch between the
hi-speed controller and the low/full speed controller. As to what actually
happens, it seems easy to test, right? For a real test get a copy of
UVCView.exe (A MS tool that's available all over the place) to expose what
each port is up to. I have another program here called bench32 that measures
USB performance.
Paul helped me with this a few months ago:
http://www.intel.com/design/chipsets/datashts/313056.htm
Go to page 218. Might not be your chipset, but the description may be
enlightening. Here's the original thread: http://tinyurl.com/6ntax7
-John O
"CTOS" <CTOS@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:6EB3A373-AFB8-410A-9E92-533B75D9CE03@xxxxxxxxxxxxxxxx
This page seems to answer your question nicely:
"9. How does USB 2.0 and 1.1 work together?"
http://www.everythingusb.com/usb2/faq.htm
"James" wrote:
I'm definitely not up to date with the world of hardware these days. The
shortest way for me to ask this is to simply write my assumption, then
question. Please let me know if my assumption is wrong.
assumption: when a 1.1 and 2.0 devices are plugged into the same usb 2.0
bus
both devices have to operate at usb 1.1 speeds.
1) does this mean even having a usb 1.1 keyboard and a fast usb 2.0
harddrive on the same 2.0 bus will kill the harddrive performance?
2) most pc's have many usb ports... are they all typically on one usb
bus,
or are there multiple buses? If multiple buses then I assume you could
group
1.1 devices on one bus and only 2.0 devices on another bus to avoid
bringing
the 2.0 devices down?
a mix of assumptions and questions there... if someone could set me
straight
on this I would really appreciate it.
thanks.
.
- References:
- question on USB 1.1 and 2.0 together
- From: James
- RE: question on USB 1.1 and 2.0 together
- From: CTOS
- question on USB 1.1 and 2.0 together
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