Minutes of SPI-2 Working Group -- Sept 9, 1996

Dave Guss/SSI1 Dave_Guss/SSI1.SSI1 at notes-gw.tus.ssi1.com
Tue Sep 17 07:56:25 PDT 1996


* From the SCSI Reflector (scsi at symbios.com), posted by:
* Dave Guss/SSI1 <Dave_Guss/SSI1.SSI1 at notes-gw.tus.ssi1.com>
*
* From the SCSI Reflector (scsi at symbios.com), posted by:
* "Lohmeyer, John" <JLOHMEYE at COSSYMWEST.CO.SYMBIOS.COM>
*

 > > >  Note: spi2r11.pdf is available on the SCSI BBS (719-533-7950) and
 > > >  on ftp.symbios.com/pub/standards/io/x3t10/drafts/spi2

Minutes of SPI-2 Working Group   
                              X3T10/96-232r0

Accredited Standards Committee*
X3, Information Technology
                                             Doc. No.: X3T10/96-232r0
                                                 Date: September 17, 1996
                                              Project: 1142-D
                                            Ref. Doc.:
                                             Reply to: John Lohmeyer

To:         Membership of X3T10

From:       Bill Ham, SPI-2 Technical Editor
            Larry Lamers, Vice-chair X3T10
            John Lohmeyer, Chair X3T10

Subject:    Minutes of SPI-2 Working Group
            September 9, 1996 -- Natick, MA


                                  Agenda

1. Opening Remarks

2. Approval of Agenda

3. Attendance and Membership

4. LVD Topics
   4.1 Hot Plugging [Ham]
   4.2 Universal Backplane [Ham/Wallace]
   4.3 SPI-2 Document Review (X3T10/1142D) [Ham]
   4.4 Relaxing Delta Vcm specification in section 13.2.2 [Harris]

5. High-Voltage Differential Fast-40 (96-190) [Gingerich]

6. SPI Single-ended Termination (X3T10/1142D) [Milligan]

7. Missing SPI Requirement (reflector message) [Milligan]

8. Configuration Rules [Ham/Gingerich]

9. Termination Power Requirements for HVD [Ham]

10. Meeting Schedule

11. Adjournment




                              Results of Meeting

1.    Opening Remarks

John Lohmeyer, the X3T10 Chair, called the meeting to order at 9:15 a.m.,
Monday September 9, 1996.  He thanked Charles Monia of Digital 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 agenda was approved with the following additions:
      7. Missing SPI Requirement (reflector message) [Milligan]
      8. Configuration Rules [Ham/Gingerich]
      9. Termination Power Requirements for HVD [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. Michael Wingard    P  Amphenol Interconnect     mikwingard at aol.com
Mr. Borden Moller      A  CMD Technology            borden at cmd.com
Mr. Louis Grantham     P  Dallas Semiconductor      grantham at dalsemi.com
Mr. Siegfried Schmalz  V  Dallas Semiconductor      schmalz at dalsemi.com
Mr. Greg McSorley      O  Data General Corp.   
       greg_mcsorley at dgc.ceo.dg.
                                                    com
Dr. William Ham        A# Digital Equipment Corp.   
  ham at subsys.enet.dec.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. Robert Bellino     P  Madison Cable Corp.   
      robert_bellino at madisonusa
                                                    .ccmail.compuserve.com  

Mr. Edward A. Gardner  P  Ophidian Designs          gardner at acm.org
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.
                                                    seagate.com
Mr. Vit Novak          A  Sun Microsystems, Inc.    vit.novak at sun.com
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. 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. Doug Piper         P  Woven Electronics         549.9900 at mcimail.com

20 People Present

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

4.    LVD Topics

4.1   Hot Plugging [Ham]

John Lohmeyer and Bill Ham discussed possible improvements in hot   
plugging for
case 4.  John noted that laboratory work seemed promising.  He suggested   
that
more extensive presentations might be forthcoming.

4.2   Universal Backplane [Ham/Wallace]

Dean Wallace noted that the simulations are proving more difficult to   
process
than he expected.  However, he expressed a belief that a universal   
backplane
layout will be possible.  Bill and Dean discussed the details of the
electrical properties of a probable universal backplane.  Dean requested   
that
further discussion be deferred until the next meeting.

Bill and John questioned whether the universal backplane should be   
included in
SPI-2.  Concerns were raised that including universal backplane   
documentation
could delay stabilizing SPI-2.  Options suggested were pushing the   
universal
backplane to EPI or to an informative annex in SPI-2 (developed after the
stabilization vote).

4.3   SPI-2 Document Review (X3T10/1142D) [Ham]

Bill stepped through revision 10 of SPI-2 soliciting comments both   
editorial
and technical.  Many of the comments were editorial.  Bill agreed to   
prepare a
revision 11 of the document based on the results of the discussions at   
this
meeting.

After lunch, there was a discussion of the Transfer Period Factor value   
to use
in the Synchronous Data Transfer Request (SDTR) Message for the Fast-40
transfer rate.  The group agreed to use a Transfer Period Factor of 10h   
for
Fast-40 and 11h for Fast-30.  Devices running at the Fast-30 data rate   
must
meet the Fast-40 setup and hold times, but will transfer and receive data   
at
30 mega-repetitions/second or less.

Values below 10 are reserved for future standardization.  Paul Aloisi
suggested some possible future assignments for these code values and Bill   
Ham
suggested an alternate set.

Transfer  Transfer       Maximum            Comments
Period    Period         Data
Factor                   Rate

 12       50 ns          Fast-20            Defined in Fast-20/SIP
 11       30.3 ns        Fast-33            To be defined in SPI-2 annex
 10       25 ns          Fast-40            To be defined in SPI-2 annex

                     Paul's      Bill's
                     Proposal    Proposal

  9                  Fast-60     Fast-100   \
  8                  Fast-80                |
  7                  Fast-120               |
  6                  Fast-160    Fast-200   |
  5                  Fast-240               > Reserved for future
  4                  Fast-320    Fast-400   | standardization
  3                  Fast-480               |
  2                  Fast-640    Fast-800   |
  1                  Fast-960    Fast-1000  /
  0       Reserved

Gene Milligan pointed out that the transfer period tolerances in SPI   
(Receive
Period Tolerance and Transmit Period Tolerance) should also apply to   
SPI-2
(and Fast-20, for that matter).  The group agreed.

The working group agreed by unanimous consent to recommend to X3T10 that   
SPI-2
Revision 10 with the agreed upon changes be technically stabilized for   
the
current content.

4.4   Relaxing Delta Vcm specification in section 13.2.2 [Harris]

Bill Ham and John Lohmeyer described recent discussions about problems   
with
the offset (common-mode output) voltage requirements in SPI-2 revision   
10.
Chip designers at both IBM and Adaptec had indicated that the current
specification would be difficult to meet.  Bill showed the definition of   
both
the DC common mode voltage requirements and the AC common mode voltage
requirements (section 13.2.5 in SPI-2).  The group discussed procedural   
issues
associated with the problem.

Bill summarized the issue as concerning common mode current and signal   
cross
talk.  The problem is mostly affected by the AC specifications (not the   
DC
specifications).  Nobody is complaining about the AC specifications.  So,   
why
not relax the DC specification?

In the absence of any objections, the group recommended changing the DC   
common
mode voltage delta in section 13.2.2 from 50 mV or less to 120 mV or   
less.

5.    High-Voltage Differential Fast-40 (96-190) [Gingerich]

John noted that Kevin Gingerich will not be attending.  Therefore,   
discussion
of this topic will be deferred to the next meeting.

6.    SPI Single-ended Termination (X3T10/1142D) [Milligan]

Gene Milligan raised an issue (see 96-222) on how the single-ended   
terminator
current is specified in SPI.  Specifically the 48 mA maximum at 0.2 V   
seems to
outlaw the existing SCSI-2 alternative-2  terminator, which can deliver   
more
than 48 mA at 0.2 V.

Dean Wallace presented a written description that proposed allowing 22.4   
mA at
0.5 V and 25.4 mA at 0.2 V for each terminator, for a total of 50.8 mA at   
0.2
V.  John noted that the silicon folks have previously rejected increasing   
the
driver current specification because of the expense of re-characterizing   
the
parts.  The group discussed the history of terminator current   
requirements at
length.  Dean agreed to revise the problem description based on the   
working
group discussion and distribute the proposal on the SCSI Reflector.

7.    Missing SPI Requirement (reflector message) [Milligan]

Gene noted that both SCSI-2 and SPI carefully specify bus capacitance for   
a
device be measured at the end of the stub for single-ended but that   
similar
requirements are needed (but not present) for differential busses.  Bill   
Ham
contested Gene's assertion and attempted to show how the differential
requirements described by Gene are present in SPI-2.

It was agreed that the desired requirement is present but not worded as   
well
as Gene desired.  Final resolution of the issue was deferred to the SPI-2
document review topic (which precedes this topic on the agenda but   
followed
this topic in the timeline of the meeting).

8.    Configuration Rules [Ham/Gingerich]

Bill presented a configuration rules proposal developed by Kevin   
Gingerich
intended to reduce the contribution to skew and propagation delay   
introduced
by configuration.  Bill noted that the proposal, in part, simply changes   
the
way the existing requirements are shown (in the standard).  Bill   
criticized
the modeling methodology on which the proposal is based and noted that   
the
results disagree with his laboratory results.  Bill then asked the group   
to
develop ideas for a better presentation of the requirements.

Bill and the group generally approved of Kevin's proposal regarding   
device
spacing.  The group substantially edited Kevin's proposal, keeping some   
parts
and returning to SPI-2 revision 10 wording for others.  In a couple of
instances, configuration rules were modified slightly to align with the
configuration rules being promoted by the SCSI Trade Association (i.e.,   
16
devices and 12 meters for LVD).

9.    Termination Power Requirements for HVD [Ham]

Bill noted an absence of defined termination power requirements for high-
voltage differential systems and displayed an editor's note on the topic   
in
clause 7.2 of SPI-2 revision 10.  Siegfried Schmalz, Dean Wallace, Paul
Aloisi, and several others described the requirements as 1 amp at 4 volts   
for
a narrow bus.  Bill described this requirement as the most difficult
termination power distribution problem in SCSI.  He then proceeded to try   
to
simplify the termination power distribution complications, with little
success.

10.   Meeting Schedule

The next meeting of SPI-2 Working Group is scheduled for October 10, 1996   
in
St. Petersburg Beach, FL with X3T11 hosted by AMP.  A subsequent meeting   
is
planned for November 4, 1996 in Palm Springs, CA.

Chair's Note:  Since X3T10 stabilized the SPI-2 working draft, it is
anticipated that the next couple SPI-2 working group meetings will focus   
on
the editorial issues of merging the SPI, SIP, and Fast-20 documents into   
SPI-
2.

11.   Adjournment

The meeting was adjourned at 7:15 p.m. on Monday September 9, 1996.

 --
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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