SAS 2 - scrambler operation

Stephen FINCH steve.finch at
Thu Jul 19 06:47:04 PDT 2007

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I'd like to address the question by use of an example.
In a normal frame (between SOF and EOF or between SOAF and EOAF), the
scrambler is not advanced is a ALIGN primitive is inserted.  In fact, the
scrambler is not be advanced when any primitive is inserted, such as RRDY or
ACK.  Since the TRAIN and TRAIN_DONE patterns consists of TRAIN and
TRAIN_DONE primitives and scrambled data then, by the example above, the
scrambler would not be advanced when the primitive portions of the patterns
are sent.
In section 7.6 it states:
"All data dwords are scrambled. Table 117 lists the scrambling for different
types of data dwords."
In a brief search of SAS-2, I didn't find an explicit statement that
primitives are not scrambled, but they aren't.
Steve Finch 
From: owner-t10 at [mailto:owner-t10 at] On Behalf Of Robert
Sent: Wednesday, July 18, 2007 4:19 PM
To: 't10 at'
Subject: SAS 2 - scrambler operation Train-SNW defines two training patterns: TRAIN pattern and
TRAIN)DONE pattern. Both are defined as their respective redundant primitive
followed by 58 dwords set to 0x00000000 scrambled and 8b10b encoded.
Furthermore, the scrambler is initialized at the end of RCDT and is not
re-initialized after that.
The question we have is : Does the scrambler pause while sending TRAIN or
TRAIN_DONE primitives; that is, is the dword following the primitive the
scrambler's successor dword to the dword preceding the primitive? Or does
the scrambler run continuously, and TRAIN or TRAIN_DONE is overlayed on top
of scrambler dwords? I would expect the former, but I don't feel that the
current draft (sas2r10) is clear in this regard.
Robert Watson
PMC-Sierra, Inc.

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