Ralph Cohen wrote:

>Informal testing I conduced about a year ago showed there could be a
>substantial difference in the transmission speeds of USB 1.1 and USB
>2.0 HiSpeed cables.  I was testing the speeds of some CF cards in a USB
>2.0 reader hooked up to a USB 2.0 port and was curious to see if the
>type of cable used made any difference.  The results surprised me -
>reported R/W speeds were 2-3 times higher when connected with USB 2.0
>HiSpeed cables than with 1.1 cables.  I went through a box of
>miscellaneous USB cables and testing consistently showed the speed over
>USB 2.0 connections to be 2-3 times higher than over 1.1 connections. 
>YMMV.
>
>Not every application can benefit from the faster USB 2.0 HiSpeed
>spec and USB 2.0 doesn't always mean hi+gh speed.  The 480Mbps USB 2.0
>speed is a part of the "HiSpeed" specification.  Plain USB 2.0 only
>operates at 12Mbps.  There are difference between USB 1.1 and 2.0 that
>have nothing to do with speed so there are different levels of USB 2.0
>compliance.  I was recently reading that part of the USB 3.0 spec will
>the ability for memory devices to transfer data without needing a
>separate computer.
>
>Ralph Cohen
>
>
>On Sat, 19 Feb 2005 04:40:22 +1000, Mike O'Connor wrote:
>
>>Hi All,
>>
>>For those that weren't already aware of it, the following off CNET is of 
>>interest:
>>
>>Q: If I have a USB 2.0-capable printer, should I go out and buy 
>>a USB 2.0 cable, or can I get the same performance using the older 
>>USB 1.0 cable that I already have? 
>>--Posted by Gary S.
>>
>>A: Despite what the text emblazoned on the packaging says, there 
>>is no such thing as a "USB 2.0 cable." A USB cable is a USB cable 
>>and should work equally well with both versions of the standard. 
>>    
>>

Hi Ralph,

That's interesting information - the two USB 2.0 cards that I've had 
interaction with have both specified transfer speeds for USB 1.1 OHCI as 
1.5Mbps,12Mbps and for USB 2.0 EHCI as 480Mbps, but I've yet to see 
anything remotely approaching those speeds, using included USB 2.0 cables!
 From the V3.0 specification looks like they're trying to get some of 
the functionality that firewire /iLink /IEEE1394 already has.

FWIW what speeds were you getting with the CF cards?

-- 
Regards,
Mike

Failed the exam for
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MCSE - Minesweeper Consultant and Solitaire Expert
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