Draft Minutes of SPI-2 Working Group 1/6/97

Lohmeyer, John JLOHMEYE at cossymwest.co.symbios.com
Tue Jan 14 15:49:00 PST 1997

* From the SCSI Reflector (scsi at symbios.com), posted by:

Minutes of SPI-2 Working Group   

Accredited Standards Committee*
X3, Information Technology
                                             Doc. No.: X3T10/97-110r0
                                                 Date: January 14, 1997
                                              Project: 1142-D
                                            Ref. Doc.:
                                             Reply to: John Lohmeyer

To:         Membership of X3T10

From: Ralph Weber, Secretary X3T10
            Larry Lamers, Vice-chair X3T10
            John Lohmeyer, Chair X3T10

Subject:    Minutes of SPI-2 Working Group
            January 6, 1997 -- Dallas, TX


1. Opening Remarks

2. Approval of Agenda

3. Attendance and Membership

4. Universal backplane [Wallace/Barnes]

5. LVD case 4 hot plugging [Barnes]

6. Changing driver modes when hot plugging (96-270) [Penokie]

7. Single-ended termination (96-245) [Wallace]

8. Proposed clarification to Fig. 24 [Ham]

9. Integration Issues [Lohmeyer/Lamers/Ham]

10. Bus Set Delay Reduction [Ham]

11. Meeting Schedule

12. Adjournment

                              Results of Meeting

1.    Opening Remarks

John Lohmeyer, the X3T10 Chair, called the meeting to order at 9:04 a.m.,
Monday January 6, 1997.  He thanked Jim McGrath and Mary Turco of Quantum   
hosting and arranging the meeting.

As is customary, the people attending introduced themselves and a copy of   
attendance list was circulated.

2.    Approval of Agenda

The agenda was approved with the following additions:

      9. Integration Issues [Lohmeyer/Lamers/Ham]
      10. Bus Set Delay Reduction [Ham]

3.    Attendance and Membership

Attendance at working group meetings does not count toward minimum   
requirements for X3T10 membership.  Working group meetings are open to   
person or organization directly and materially affected by X3T10's scope   
work.  The following people attended the meeting:

         Name          S        Organization         Electronic Mail   
 ---------------------- -- -------------------------   
Mr. Norm Harris        P  Adaptec, Inc.   
            nharris at eng.adaptec.com
Mr. Lawrence J. Lamers A  Adaptec, Inc.             ljlamers at aol.com
Ms. Lisa Huff          V  AMP, Inc.                 lisa.huff at amp.com
Mr. Ron Roberts        A  Apple Computer            rkroberts at aol.com
Mr. Richard Wagner     P  Cable Design Technologies   
rwagner at montrose-cdt.com
Mr. Edward Haske       P  CMD Technology            haske at cmd.com
Mr. Siegfried Schmalz  A  Dallas Semiconductor      schmalz at dalsemi.com
Mr. Bruce McLaren      V  Dallas Semiconductor   
     bruce.mclaren at dalsemi.com
Dr. William Ham        A# Digital Equipment Corp.   
  ham at subsys.enet.dec.com
Mr. Roger Cummings     P  Distributed Processing   
   cummings_roger at dpt.com
Mr. George Penokie     P  IBM Corp.   
                gop at rchvmp3.vnet.ibm.com
Mr. Dean Wallace       P  Linfinity Micro   
          75671.3443 at compuserve.com
Mr. Louis Grantham     A  Linfinity Micro   
          lgdatcom at ix.netcom.com
Mr. E. Jake Berzon     P  NEC Electronics, Inc.   
    jberzon at asic.mtv.nec.com
Mr. Skip Jones         P  QLogic Corp.              sk_jones at qlc.com
Mr. Richard Uber       V  Quantum Corp.             duber at tdh.qntm.com
Mr. Gene Milligan      P  Seagate Technology        Gene_Milligan at notes.
Mr. Gerald Houlder     A  Seagate Technology        Gerry_Houlder at notes.
Mr. John Lohmeyer      P  Symbios Logic Inc.   
       john.lohmeyer at symbios.com
Mr. Ralph O. Weber     A  Symbios Logic Inc.        roweber at acm.org
Mr. Paul D. Aloisi     P  Unitrode Corporation      aloisi at unitrode.com
Mr. Gregory Kapraun    V  Western Digital Corp.     kapraun at wdroc.wdc.com
Mr. Doug Piper         P  Woven Electronics   
        doug.piper at internetmci.com

23 People Present

Status Key:  P    -  Principal
             A,A# -  Alternate
             O    -  Observer
             L    -  Liaison
             V    -  Visitor

4.    Universal backplane [Wallace/Barnes]

John Lohmeyer asked what happens next (after the very through discussion   
Palm Springs).  Bill Ham expressed the belief that an informative annex   
be written.  John asked for volunteer(s) to write the annex.  Other   
locations for the information were discussed.  Dean Wallace volunteered   
write the annex, provided Larry Barnes agrees to review it.

Dean asked how much of the "text book" material should be in the annex.   
stated a preference for all of it.  Others (perhaps the uninformed)   
that the "how to build backplanes" information could be included by   
This idea and several others were discussed.  Dean received no clear   
on the subject.

5.    LVD case 4 hot plugging [Barnes]

John Lohmeyer announced that he had not received Larry Barnes' simulation   
and thought that it had not been completed due to software problems.   
noted that he will discuss the simulation with Larry when he returns to   
office.  John said Larry had been assigned to other projects and may not   
time to finish the simulation.  Larry Lamers asked if the data input for   
simulation were available.  John thought he could obtain the data.

Bill Ham, Dean Wallace, Larry Lamers and John discussed the usefulness of   
simulation (and laboratory testing, for that matter).  It seemed that
simulation and testing provided valuable starting points, but could be
overturned by "real world" experience.  The details of the simulation
methodology also were discussed.

John agreed that the item will remain on the agenda for at least one more

6.    Changing driver modes when hot plugging (96-270)  [Penokie]

George Penokie presented (96-270) a document proposing additions to   
SCSI standards that provide for software notification of changes in
transceiver operating mode (particularly LVD to SE; Low-Voltage   
to Single-Ended).  John Lohmeyer raised concerns over the asymmetric   
nature of
the required notifications.  In particular, notification is required for   
to SE but not for SE to LVD.  In addition, George received several   
corrections.  After much discussion, George agreed to add symmetrical
requirements for notification of changes from SE to LVD.

Gene Milligan suggested that once a bus changes from LVD to SE, the only   
to change back would be a power-cycle.  The group questioned this concept   
discussed the matter at length.  Gene stated that the reason for his   
was that once a device enters single-ended mode, it drives DIFFSENS to   
Several other people argued that multi-mode devices would not drive   
to ground while in SE mode; they would continue to source current on   
to attempt to re-enter LVD mode.  Gene mentioned that some muli-mode   
might have a jumper to force single-ended mode.  The group agreed that   
devices should ground the DIFFSENS line when the jumper forces   
mode, because such devices effectively are only single-ended devices.

John Lohmeyer also discussed the timing issues around transition testing   
the DIFFSENS line.  John reviewed the discussion as recent editing   
He noted that the most recent editing meeting agreed that the 100   
transition delay should remain (unchanged) to guarantee filtering of   
50/60 Hz
noise on the DIFFSENS line.

The group discussed issues concerning transitions to and from LVD   
operation at
length.  The discussion was complicated by the introduction of bus   
to the proposed configurations to be covered.  The discussion was lengthy   
detailed.  Virtually all present participated in the discussion at one   
time or
another.  Bus expanders appeared to present the greatest difficulty.

Eventually, the group agreed that a device (initiator or target) that   
change in DIFFSENS mode shall generate an internal reset.  The group   
agreed that a bus expander that senses a change in DIFFSENS mode shall
generate a hard reset on the other bus.

George agreed to generate a revision 1 of the proposal, including all the
resolutions reached during this meeting.  George will bring the revised
proposal to the next working group meeting.

7.    Single-ended termination (96-245r1) [Wallace]

Dean Wallace reported that several comments were received regarding the   
revision of the proposal.  He drew the figure and described the changes
proposed and the comments received from Seagate and others regarding the
proposed changes.

Bill Ham raised two additional concerns.  Part of Bill's issue was that   
he was
willing to make old terminators illegal in SPI-2, while Dean was   
interested in
making minor changes that allow old terminators to comply with SPI-2.   
pressed for resolution of four issues: maximum current, minimum current,
sinking current, and linearity.  Dean noted that the proposal must be   
further to meet Bill's requirements.  The idea of basing terminators on   
ohms or 70 ohms (instead of 110 ohms) was also discussed.

Dean agreed to integrate the changes discussed by the working group into   
a new
revision of the proposal.

8.    Proposed clarification to Fig. 24 [Ham]

Bill Ham reviewed the proposed clarification for SPI-2 (rev 11) figure   
24.  He
noted that some might view the change as technical, but Bill expressed   
belief that the change is not significant (about 30 pico-seconds in the   
budget).  After a brief discussion, the group agreed to distribute the
proposal as a separately numbered X3T10 document for review and   

9.    Integration Issues [Lamers]

1.    Active negation - map of existence (see X3T10/95-295); map of   
   (use F20 envelope)
   The group agreed that this issue was considered and resolved at the   
   working group meeting (see 96-257).

2.    SE termination, max/min current & sinking of current (see X3T10/96-
   222r1); suggest min current 20 milliamps at 0.2 v DC and a max of 25.4
   milliamps at 0.2 v DC;  don't require driver to sink this to avoid   
   add a min at 0.5 v DC; how to deal with non-linear terminators; do we   
need a
   duty-cycle spec? suggest 20 asserted signals for wide, 12 on narrow,   
37 on 32-
   bit.  Add exception for a contained bus (e.g., laptop) of less than   
   meters. Add a 12.5 pf max capacitance for terminator.
   The group agreed that this issue was considered and resolved at the   
   working group meeting (see 96-257).

3.    Leakage spec increased for LVD multi-mode drivers to 20 micro-amps   
   Resolve by specifying one for each driver type.
   The group agreed that this issue was considered and resolved at the   
   working group meeting (see 96-257).

4.    Latching & counting - require that they be an atomic action for hot
   plugging - possibly an annex or implementation note.
The group agreed that this issue was considered and resolved at the last
working group meeting (see 96-257).

5.    Ground - power, logic & ground drivers (25-pin power & ground   
   (SFF-8040)), signal ground and ground ground for tables defining SE   
The group agreed that this issue was considered and resolved at the last
working group meeting (see 96-257).

6.    SE Receiver - hysterisis (.3), input levels (adopt F20), pin   
   (same), glitch filtering (enable of first detection of a transition   
for 'x'
   duration).  Need an algorithm to determine 'x'.

   The group discussed the desire to use the tighter Fast-20 requirements   
   SPI) for the described values.  Gene Milligan raised concerns about   
   definitions of the requirements on the DIFFSENS line (for historical   
   Voltage Differential implementations).  Patent issues related to   
   filters were discussed; it is important that the standard not require   
   specific implementation to avoid various glitch filter patents that   
may exist.

   The group agreed to propose that Fast-10 SCSI use the same glitch   
   that SPI has, except that glitch filtering would be required for the   
   edge, as well as the negation edge.  For Fast-20, glitch filtering   
would be
   required for the assertion edge, as well as the negation edge, and   
that the
   time during which signal reversals shall be ignored would be 7 ns,   
instead of
   10 ns.  Fast-40 would have all the properties of Fast-20 with a glitch
   filtering interval of 4 ns.   Thus, x will be 10 for Fast-10 and 7 for   
   and 4 for Fast-40.  The group agreed that filtering would apply only   
to the
   REQ and ACK receivers.

   John asked that the silicon folks examine the above proposal (for REQ   
and ACK
   glitch filtering) and provide input on its feasibility at the March   

7.    SE Drivers - slew rate (use F20 specs)
   The group agreed to used the Fast-20 specs for slew rate.

8.    16 or 32 devices? 32-bit data path? Is it a single segment draft?
   Should expanders be included?  Suggest that SPI-2 is 16 loads per   
segment max;
   allow 32-bit data path and 32 SCSI IDs addressability when using VHDCI
   connectors with primary and secondary cables

   Larry raised the question of how SCSI is described in the foreword and   
   of the SPI-2 standard.  The group discussed various aspects of the   
   including cables, protocol chips, bus expanders and several other   
   components.  Most of the discussion concerned implementation of 32 bit   
   parallel SCSI busses.

   The group agreed to leave the 32-bit data path and stick with a limit   
of 16
   devices per segment.

9.    Case 4 hot plugging - requires SCA-2 connectors to allow   
pre-charge, a
resistive contact may also work, needs research to determine max   

It was noted that the glitch filter decisions (taken earlier in this   
tightens restrictions on case 4 hot plugging, at least with respect to
reflected glitches.  Bill Ham expressed the belief that better glitch
filtering will not help resolve the case 4 problem.  Larry Lamers   
that this means that minimizing the disturbance produced by hot plugging   
the only avenue to a solution.  Lisa Huff indicated that disturbance   
via resistive contacts was not fully designed and tested yet.

The group determined that additional research is required on this   

10.   Cable specifications - impedance (loaded & unloaded), skew, wire   

Larry Lamers and Bill Ham asked if SPI-2 should use SPI or LVD/SPI-2   
requirements.  Bill Ham proposed that cable vendors be asked, "If you did   
the Fast-20 spec cable, what would that do to LVD?" and "Do the Fast-20   
defining the cable and the equivalent requirements in SPI-2/LVD describe   
same cable?" and "If the two cables are different, what is required to   
them the same?"

The group agreed to "go for the best cable and one cable for everything."
Bill noted that this may result in SPI-2 requiring a cable that is   
|from all previously specified cables.

11.   Add Q-cable pinouts

   The group agreed to just do it.

12.   Micro SCSI pinouts

   Bill Ham and George Penokie discussed the usefulness of the micro SCSI
   connector.  Substantial resistance was encountered for including the   
   SCSI connector.  The group agreed to remove describing the micro SCSI
   connector from the work list for SPI-2.  It was noted that SFF will   
   the micro SCSI connector.

13.   Reserved lines

Bill Ham proposed that SPI-2 clearly describe reserved lines as being
ungrounded, continuous from end-to-end, and not terminated.  The group   
with most of Bill's proposal, but final resolution of reserved line   
in the terminator was left open for additional discussion at a future   

14.   Fair Arbitration

John Lohmeyer described the "Fair Arbitration" issue as a placeholder,   
that inclusion of fair arbitration is a work item for the final SPI-2
document.  A previous working group has recommended that the IBM fairness
algorithm be included in SPI-2; work is still needed to convert the   
terminology to SPI-2 terminology.

10.   Bus Set Delay Reduction (97-116) [Ham]

Bill Ham presented a proposal to change the Bus Set Delay from 1800 ns to   
ns.  He described the reasoning behind his proposal.  In a pathological   
the 1800 ns Bus Set Delay limits the maximum one way domain propagation   
to 300 ns, under the worst condition.  The existing, preferred, one way   
propagation delay is 400 ns.

John Lohmeyer described the SCSI timing model, from which the 1800 ns   
time was
derived.  He expressed the belief that Bill should consider modifying the
inputs to the SCSI timing model, the spreadsheet for the model, which   
agreed to send to Bill.  In the process of discussing the model, Bill
discovered that many other interesting parameters could be modified, if   
to the model are adjusted.  A key input to the model was the accuracy of   
clock signal provided to a chip that is running the parallel SCSI   

The group digressed to a lengthy discussion of reducing arbitration   
Changing model inputs was only one topic discussed during the digression.
Other, more significant, changes to reduce overhead also were discussed.

Eventually, the group agreed that representatives of SCSI protocol chip   
will discuss the proposed reduction of Bus Set Delay with their design
engineers.  Bill agreed to revise 97-116 based on the discussions at this
working group meeting.

11.   Meeting Schedule

The next meeting of SPI-2 Editors is scheduled for Thursday February 6,   
in San Jose, CA with X3T11 hosted by Sun Microsystems.  A subsequent   
group meeting is planned for Monday March 10, 1997 in San Diego, CA.

The group discussed the need for every-month meetings.  The need for   
meetings appeared to be diminishing.  Still, the group decided to   
monthly meetings for another bi-monthly cycle.  Based on this decision,   
will schedule a meeting in conjunction with the X3T11 meeting in April in   
Springs, CA, hosted by Brocade at the Hyatt Suites (specifics of the   
to be announced during the March X3T10 meeting week).

12.   Adjournment

The meeting was adjourned at 5:52 p.m. on Monday January 6, 1997.

John Lohmeyer                 E-Mail: john.lohmeyer at symbios.com
Symbios Logic Inc.             Voice: 719-533-7560
4420 ArrowsWest Dr.              Fax: 719-533-7036
Colo Spgs, CO 80907-3444    SCSI BBS: 719-533-7950 300--14400 baud

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