Minutes of SPI-2 Study Group Meeting 11/6/95

Lohmeyer, John JLOHMEYE at cosmpdaero.ftcollinsco.ncr.com
Sun Nov 12 21:09:00 PST 1995


Note: The mailing deadline is Wednesday 11/15/95.  If you have any comments 
on these minutes that you want included in the mailing, get them to me by 
noon on Wednesday.  -- John (john.lohmeyer at symbios.com)

Minutes of SPI-2 Study Group Meeting 
                           X3T10/95-340r0

Accredited Standards Committee*
X3, Information Technology
                                                   Doc. No.: X3T10/95-340r0
                                                       Date: November 12, 
1995
                                                    Project: 1142-D
                                                  Ref. Doc.:
                                                   Reply to: John Lohmeyer

To:         Membership of X3T10

From:       Ralph Weber, Secretary X3T10
            John Lohmeyer, Chair X3T10

Subject:    Minutes of X3T10 SPI-2 Study Group Meeting
            Palm Springs, CA -- November 6, 1995


                                       Agenda

1. Opening Remarks

2. Approval of Agenda

3. Attendance and Membership

4. Report from Marketing Meeting [Lohmeyer]

5. LVDS Terminator Specifications [Aloisi / Brown]

6. LVDS Driver/Receiver Specifications
   6.1 Review of Signal and Power Budgets
   6.2 Common Mode Range [Gasparik]
   6.3 Test Circuits and Limits [Ham]
   6.4 Balance [Ham]
   6.5 How to get off the bus [Uber]

7. LVDS Cable Specifications
   7.1 Crosstalk testing [Spitler]
   7.2 The Case for 50 Ohm Cables (95-308r0) [McCall]

8. LVDS Testing Results [Ham]

9. Other Topics
   9.1 Error in SPI-1 SCAM Annex B [Penokie/Lohmeyer]
   9.2 Error in SPI-1 Cabling Measurement Annex D [Daggett/Lohmeyer]
   9.3 Configuration Rules [Ham]
   9.4 Hot Plugging [Ham]

10. Meeting Schedule

11. Adjournment




                              Results of Meeting

1.    Opening Remarks

John Lohmeyer, the X3T10 Chair, called the meeting to order at 9:07 a.m.,
Monday November 6, 1995.  He thanked Jeff Stai of Western Digital Logic for
hosting the meeting.

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

2.    Approval of Agenda

The draft agenda was approved with the addition of the following items:

      4. Report from Marketing Meeting [Lohmeyer]
      6.2 Common Mode Range [Gasparik]
      6.3 Test Circuits [Ham]
      6.4 Balance [Ham]
      6.5 How to get off the bus [Uber]
      9.3 Configuration Rules [Ham]
      9.4 Hot Plugging [Ham]

and the removal of the following items:

      9.1 Document review (95-315) [Ham]

3.    Attendance and Membership

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

Name                   S  Organization              Electronic Mail Address
 ---------------------- -- ------------------------- 
 -------------------------
Mr. Norm Harris        P  Adaptec, Inc.             nharris at eng.adaptec.com
Mr. Lawrence J. Lamers A# Adaptec, Inc.             ljlamers at aol.com
Mr. Wally Bridgewater  V  Adaptec, Inc.             wally at eng.adaptec.com
Mr. Jimmy Lie          V  Adaptec, Inc.             jimlie at eng.adaptec.com
Mr. Edward Fong        P  Amdahl Corp.              esf10 at amail.amdahl.com
Mr. Dennis R. Haynes   O  Burr-Brown Corp.          haynes_dennis at bbrown.com
Mr. William C. Gintz   V  Conner Peripherals        bill.gintz at conner.com
Mr. Louis Grantham     P  Dallas Semiconductor      grantham at dalsemi.com
Mr. Charles Monia      P  Digital Equipment Corp.   monia at shr.dec.com
Mr. Douglas Hagerman   A# Digital Equipment Corp. 
  hagerman at starch.enet.dec.
                                                    com
Dr. William Ham        A# Digital Equipment Corp.   ham at subsys.enet.dec.com
Mr. Ralph O. Weber     A# ENDL Associate            roweber at acm.org
Mr. Andy Chen          A# Fujitsu Computer Prods    achen at fcpa.fujitsu.com
                          Amer
Mr. Ruben Yomtoubian   V  Hitachi                   r_yomtoubian at hitachi.com
Mr. Dan Colegrove      A# IBM Corp.                 colegrove at vnet.ibm.com
Mr. Pat LaVarre        A# Iomega Corp.              p.lavarre at ieee.org
Mr. Dean Wallace       P  Linfinity Micro 
          75671.3443 at compuserve.com
Mr. Pete McLean        P  Maxtor Corp.              pete_mclean at maxtor.com
Mr. Jay Neer           A  Molex Inc.                jneer at molex.com
Mr. Edward A. Gardner  V  Ophidian Designs          gardner at acm.org
Mr. Skip Jones         P  QLogic Corp.              sk_jones at qlc.com
Mr. Ting Li Chan       A  QLogic Corp.
Mr. James McGrath      P  Quantum Corp.             JMCGRATH at QNTM.COM
Mr. Richard Uber       V  Quantum Corp.             duber at tdh.qntm.com
Mr. Gene Milligan      P  Seagate Technology        Gene_Milligan at notes.
                                                    seagate.com
Mr. Gerald Houlder     A  Seagate Technology        Gerry_Houlder at notes.
                                                    seagate.com
Mr. Stephen G. Finch   P  Silicon Systems, Inc.     steve.finch at tus.ssi1.com
Mr. Dave Guss          A  Silicon Systems, Inc.     dave.guss at tus.ssi1.com
Mr. Robert N. Snively  P  Sun Microsystems Computer bob.snively at eng.sun.com
                          Co
Mr. John Lohmeyer      P  Symbios Logic Inc. 
       john.lohmeyer at symbios.com
Mr. Frank Gasparik     V  Symbios Logic Inc. 
       frank.gasparik at symbios.com
Mr. Tracy Spitler      V  Symbios Logic Inc. 
       tracy.spitler at symbios.com
Mr. Kevin Gingerich    V  Texas Instruments         4307725 at mcimail.com
Mr. Tokayuki Totani    O  Toshiba America           ttotaniAtaisdpd.geis.com
Mr. Kenneth J. Hallam  P  UNISYS Corporation        ken.hallam at mv.unisys.com
Mr. Paul D. Aloisi     P  Unitrode Integrated       Aloisi at uicc.com
                          Circuits
Mr. Jeff Stai          P  Western Digital           stai at dt.wdc.com
                          Corporation
Mr. Tak Asami          A  Western Digital           asami at dt.wdc.com
                          Corporation
Mr. Arnold Limjoco     O  Yamaichi Electronics      6371175 at mcimail.com
Mr. Don Johnson        V  Zitel Corporation         djohnson at zitel.com

40 People Present

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

4.    Report from Marketing Meeting [Lohmeyer]

John reported that the first meeting of a parallel SCSI marketing group was
held in the Milpitas on 16 October.  The minutes from the meeting were 
posted
on the SCSI Reflector around the end of October.

John reported on a discussion of whether to partition the LVDS work from
single-ended SCSI.  He described the reasoning behind the partitioning
proposal as being a possible need to document LVDS before all of SPI-2 can 
be
documented.  He said that the marketing group had preferred expediting the
LVDS work, but did have a specific suggestion regarding the standards
partitioning -- they left those decisions to the standards body, X3T10.

Gene Milligan asked about low-pin count requirements in the market.  Jim
McGrath reported that the marketing group discussed pin count in terms of
product cost.  The current limit for low-cost chips is 208 pins.  But, Jim 
was
not certain that an LVDS solution could be supported in 208 pins.  The cost
transition for more than 208 pins was described as a price cliff.  This
problem mostly affects disk drive manufacturers as they have very high
integration levels.

Norm Harris raised concerns about market confusion that could occur if
multiple solutions are used for LVDS and single-ended.  Bill Ham stated that
the LVDS pin count delta is 27 pins.  Gene Milligan noted that 27 might not 
be
the total pin count delta, because additional pins might needed for caching
(DRAM) access.  Steve Finch said that, for his company, 27 plus 18 pins for 
a
wider DRAM path will cost $1.

Dean Wallace reported that a supplier uses PLCC packages for 208 pins and 
BGA
for 256 pins.  The BGA package costs 40% more but has 10% better yields. 
 The
overall board cost is a wash.

Gene Milligan called on the group to include an enhancement to single-ended 
in
SPI-2, for the low-cost interface. John noted that the group could document
Fast-40 single-ended, but the cable lengths and numbers of devices would
probably have to be cut in half again -- a not very attractive alternative.
Also, the signal and cable characterizations must be done by someone 
qualified
 -- most likely Bill Ham.  Bill's time and resources are limited and Bill is
currently placing priority on LVDS.

5.    LVDS Terminator Specifications [Aloisi / Brown]

Dean Wallace and Bill Ham presented Differential Termination I-V
Characteristics slides.  Dean's slide can be found in document 95-347.  The
discussion started with Bill Ham questioning attempts to reduce to zero the
voltage at the zero current crossing.

Bill said that several discussions had shown that the group (or some members
thereof) could design the desired common-mode termination circuits.  But, he
wanted the group to develop a way to specify that circuit, exclusive of
specific circuit specs.  The group spent over an hour developing the 
circuit-
independent specifications.  Bill Ham will draft a new revision of 95-315
based on the results of the study group discussion.  He hopes to have the 
new
draft ready for the November mailing.

6.    LVDS Driver/Receiver Specifications

      6.1   Review of Signal and Power Budgets

The working group did not discuss this item due to time constraints.

      6.2   Common Mode Range [Gasparik]

Frank Gasparik presented a series of common-mode issues.  His slides can be
found in 95-346r0.  The group took note of Frank's issues and agreed that 
the
issues must be considered when other specific aspects of the LVDS 
definitions
are developed.

Based on the issues Frank presented, Bill agreed to change transmitter on-
current to 4.4 mA minimum, off to on skew (-signal to +signal) to 500 pS
maximum, on to off skew (+signal to -signal) to 500 pS maximum, common mode
compliance voltage to 1.8 volts maximum and 0.7 volts minimum.  Also, the
receiver common mode dc specification was changed to 1.8 volts maximum and 
0.3
volts minimum.

The issue on common-mode voltage was left unresolved until more test data 
can
be presented.

      6.3   Test Circuits and Limits [Ham]

With help from Kevin Gingerich, Bill presented several circuit figures from 
95-
315r3 and asked the group to comment on and correct them.  Bill noted the
corrections and agreed to include them in the next revision of 95-315.

      6.4   Balance [Ham]

Bill noted that test circuit number 3 (in the terminator discussion) has 
been
added to handle balance.  Also, the driver balance has been set in the 
common-
mode voltage discussion.

      6.5   How to get off the bus [Uber]

Richard Uber presented a concern with impedance mismatch that he felt would
necessitate impedance changes in the LVDS design.  Bill Ham felt that the
situation was similar to high-power differential.  Bill noted that protocol
features, like bus settle delay, are present to compensate for the concern.
Richard presented four possible solutions for the problem.  John proposed 
more
study from a protocol point of view.  Bill suggested more study on the rate 
of
change to high impedance.

The group agreed to consider the issues raised. but expressed uncertainty 
that
any major changes will be needed.

Richard next presented concerns over incident waves on assertion.  After 
some
discussion, the group agreed that driver minimum current requirements may 
need
to be raised, probably to 5 mA.  The issue was left open, mostly due to
concerns over possible needs to raise the maximum current.

7.    LVDS Cable Specifications

      7.1   Crosstalk testing [Spitler]

Tracy was prepared to present the same data he had at the Denver meeting, 
but
because of the late hour, review of this testing data was deferred.

      7.2   The Case for 50 Ohm Cables (95-308r0) [McCall]

Because of the late hour, the discussion of 50 ohm cables was removed from 
the
agenda.  This item will be dropped from future agendas unless new data is
brought in.

8.    LVDS Testing Results [Ham]

Bill Ham presented some testing results as part of other discussion topics,
but made no specific testing results presentation.

9.    Other Topics

      9.1   Error in SPI-1 SCAM Annex B [Penokie/Lohmeyer]

John noted that George Penokie has discovered a timing inconsistency in a 
SCAM
state diagram regarding the time from power on to SCAM selections.
He reminded the group that the fixes will need to be applied to SPI-2.

      9.2   Error in SPI-1 Cabling Measurement Annex D [Daggett/Lohmeyer]

John noted that some gross errors were introduced in converting cable
preparation measurements to metric (strip lengths are 10x what they should
be).  He reminded the group that the fixes will need to be applied to SPI-2.

      9.3   Configuration Rules [Ham]

Bill agreed to defer discussion of most of his configuration issues to the
December meeting.

The issue that Bill chose to discuss was how to measure capacitance.  Bill
received guidance regarding several key issues that must be considered when
measuring capacitance.

Wally Bridgewater asked about using TERMPWR to operate an LVDS/single-ended
translator.  John noted that the TERMPWR would most likely have to come from
the single-ended side of the translator as the LVDS side would not have
adequate power available.  The concern about using TERMPWR is that SPI 
appears
to prohibit such usage, but such products would be rather expensive if a
separate power source must be used.  There were no immediate solutions to 
the
dilemma, however the group did offer some pointers for additional study.

      9.4   Hot Plugging [Ham]

Bill stated a belief that LVDS hot plugging will be very likely generate bit
errors.  If more careful controls on REQ/ACK counting are adopted, then the
problems may not be as serious.  Bill asked that the agenda item be kept for
future meetings.

10.   Meeting Schedule

The next meeting of SPI-2 Working Group will be Friday December 15, 1995, in
San Jose, CA at the Holiday Inn in Milpitas, CA  (408-321-9500), hosted by
Quantum Corp.  Another SPI-2 Working Group meeting is scheduled for January 
8,
1996 in Dallas, TX hosted by Quantum.  Another SPI-2 Working Group meeting 
is
planned for February 5, 1996 in Denver.

11.   Adjournment

The meeting was adjourned at 7:02 p.m. on Monday November 6, 1995.




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