Multiple Commands in USB-2 - UAS

Curtis Stevens curtis.stevens at
Wed Aug 19 09:02:57 PDT 2009

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Madhukar, when UAS talks about High Speed operation or Full Speed operation
it is referring to USB-2.  When UAS talks about Super Speed it is referring
to USB-3…
The purpose of adding the READ READY IU and the WRITE READY IU is to enable
multiple commands for USB-2.
Curtis E. Stevens
Sr. Staff  Engr - Standards & Features Technology
20511 Lake Forest Drive #A 113-F
Lake Forest, California 92630
Phone: 949-672-7933
Cell: 949-307-5050
E-Mail: Curtis.Stevens at  
From: owner-t10 at [mailto:owner-t10 at] On Behalf Of
Gerry.Houlder at
Sent: Wednesday, August 19, 2009 7:01 AM
To: madhukar.gubba at; t10 at
Subject: Re: Multiple Commands in USB-2 - UAS
I would say yes. The important thing to allow multiple commands is that the
and ERDY for USB-3) have a tag so that data being transferred can be
correctly associated with its command. This information is defined to be in
place for both USB-2 and USB-3. I believe there are some restrictions on
interveaving data (i.e., once data transfer starts for a command, all data
for that command must be transferred before data can be transferred for
another command).
 Madhukar <madhukar.gubba at>
Madhukar <madhukar.gubba at> 
Sent by: owner-t10 at
No Phone Info Available 
08/19/2009 07:05 AM
t10 at
Re: Multiple Commands in USB-2 - UAS
* From the T10 Reflector (t10 at, posted by:
* Madhukar <madhukar.gubba at>
> I was going through Multiple Commands in UAS spec. The spec did not
> mention if multiple commands is supported in USB-2. I would like to
> know if multiple commands is
> handled in USB-2 or is it only supported for USB-3.
It has been two days, but there is no answer. I'm having troubles
while implementing multiple commands in USB-2. I wanted to make sure
if multiple commands can be supported in USB-2.
Please let me know.
Thanks And Regards,
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