No subject

Thompson, Ken kthompso at
Fri Nov 11 07:01:00 PST 1994

Regarding this serial shoot out thing.
There are simple schems where ONE data line can be used for bidirectional 

>From the direct attach disk adhoc meeting:


Bob Snively brought up the subject of using two backplane pins for
serial-in/serial-out shift registers.  These registers would be used
to turn on and off LEDs, sense environmental conditions, etc.  Dal and
Bob disagreed on how to use the bits (whether drive SUPPLIES or merely
RECEIVES information).  Dal wanted to be able to insert a card in
place of a drive which gathers information on behalf of some
management entity, whether it's SCSI-based (e.g., SEND/RECEIVE
DIAGNOSTIC) or IP (e.g., SNMP).  Dave Ford mentioned that some systems
have a separate SCSI Device on the bus which gathers this information.

RS-232 with 7 SEL lines can address any drive in a cabinet without the
need for encoding addresses serially.  Dal wanted to move intelligence
requirements away from drive.  It was expected that the SFF group in
Palm Springs would address some of these issues.  Another scheme could
have a controlling entity performing the data acquisition/control over
point-point links to each drive (similar to a Port Bypass manager).

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