What is SPI-2 anyway???
GOP at rchvmp3.vnet.ibm.COM
Tue Jun 11 14:38:49 PDT 1996
* From the SCSI Reflector, posted by:
* "George Penokie" <GOP at RCHVMP3.VNET.IBM.COM>
The SPI-2 working group minutes indicate the the issue of LDV as a
stand alone standard was discussed:
WG>The obvious solution to the conflicting needs is to develop two
WG>standards: one would document LVD technology and the other would
WG>document the entire SCSI parallel physical layer.
WG>Assuming X3T10 agrees, the current SPI-2 document (Project 1142-D)
WG>would continue on its previous path and be forwarded as soon as
Was I hallucinating or didn't the plenary spend an hour or two
discussing this issue with the results being a solid vote against
making LVD as a stand alone standard.
P>Gene Milligan moved to amend the motion to add a requirement that
P>X3T10 produce an additional standard covering just LVD. The motion
P>to amend to failed for lack of second.
Note here that the idea of having LVD in it's own standard could not
even get a second!!!!
The reasons for not wanting another parallel standard were that we
already have 2 (or 3 depending if you include SCSI-2) standards that
define parallel SCSI. This conglomeration of standards is making it
almost impossible to design a device that supports all the
variations. Add in yet another parallel standard and the
complexity of making a parallel devices goes up again. Maybe that's
OK for chip manufactures but it is not for device manufactures and
systems integrators that have to put all these things together and
expect them to work.
A second issue that came up at the working group is the 'what's in
WG>John had drafted a new project proposal for the combined document
WG>that he called "SCSI Unified Parallel Requirements (SUPR)". The
WG>SUPR document would contain the entire SCSI parallel definition up
WG>to and including SIP. This project would also attempt to resolve
WG>the differences between SCSI-2, SPI, Fast-20, and the current LVD
WG>work (e.g., cable impedance specification, driver/receiver
WG>switching thresholds, slew rate specifications, etc.)
Again this does not match what the plenary voted to place into SPI-2:
P>...it was moved that the operating SPI-2 project scope be clarified
P>to show that SPI-2 must include SPI, Fast-20, Fast-40, Fast- 80, and
P>LVD. The motion passed 25:4:1:19=49.
P>Ed Gardner moved that the SPI-2 technical editor be directed to
P>eliminate all references to SCSI-2 from SPI-2 by incorporating the
P>referenced material into SPI-2 as deemed appropriate. Bill Ham
P>seconded the motion. The motion passed 20:5:1:23=49.
P>John Lohmeyer moved that the inclusion of Fast-80 in SPI-2 scope be
P>reconsidered and removed from the required contents of SPI-2. Ed
P>Gardner seconded the motion to reconsider. The motion to reconsider
Besides LVD there is no mention of adding SIP into SPI-2. Although
has a certain appel to me ;) the amount of work would be enormous.
That activity should only be attempted after there is a stable SPI-2
(defined by the plenary). That would be a good activity for a SPI-3.
One other thing is that it looks to me like the working groups SPI-2
or SUPR would create yet another set of parallel requirements to
design to. So the parallel document count from the working
group would be:
and someday SUPR.
Were the plenarys view would cause SCSI-2, SPI, FAST-20, and LVD into
one standard SPI-2.
No matter how long it would take to do the combined SPI-2 it will
take at least twice as long to do a SUPR so you would be stuck having
four parallel standards for a loooooong time.
Bye for now,
PS I was not at the SPI-2 working group meeting.
More information about the T10