SPI Command IU CDB clarification

Day, Brian bday at lsil.com
Tue Sep 5 14:08:57 PDT 2000

* From the T10 Reflector (t10 at t10.org), posted by:
* "Day, Brian" <bday at lsil.com>

I've had another engineer interpret the CDB field differently than I had in
the SPI command IU CDB field.  The MSB/LSB notation was a little confusing.

The CDB field is defined at bytes 4 through 19 in the Command IU
(referencing Table 35 in SPI-3).  I've always thought the Operation Code for
that CDB would be located byte 4, which would be the first byte of the CDB
to get transferred across the bus.  However, my colleague interpreted it to
be byte 19 because of the LSB notation.

As a specific example, if an initiator was sending a 10-byte WRITE command,
does the 0x2A come out on byte 4, or byte 19.

Can someone please clarify....

Brian Day 
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