Block Reads on 2-Wire miniSAS HD Management Interface

Olawsky, Barry Barry.Olawsky at
Fri Jul 31 11:57:53 PDT 2009

* From the T10 Reflector (t10 at, posted by:
* "Olawsky, Barry" <Barry.Olawsky at>
In response to the "block read" question posed during the PHY meeting on
7/30/2009, virtually all 2-wire serial EEPROM devices currently available
support sequential reads (block reads). 
Adding the requirement for sequential read support may not appear necessary
for discrete EEPROM implementations but is probably prudent for
micro-controller implementations. For the latter, existing 2-wire interface
cores lacking support for sequential reads may end up being used due to cost
or availability of an existing core design. Explicitly defining sequential
read and write operations should prevent that from occurring.
I recommend including this requirement in the timing diagram section of the
SFF QSFP document. Timing of the serial data line state determines if the
access is sequential or single byte.
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