Minutes of SPI-2/ESPC Study Group Meeting 7/10/95

Lohmeyer, John JLOHMEYE at cosmpdaero.ftcollinsco.ncr.com
Tue Jul 18 14:57:00 PDT 1995


Minutes of SPI-2/ESPC Study Group meeting in Colorado Springs, CO 
X3T10/95-263r0



Accredited Standards Committee*
X3, Information Technology
                                                      Doc. No.: 
X3T10/95-263r0
                                                          Date: July 18, 
1995
                                                       Project:
                                                     Ref. Doc.:
                                                      Reply to: John 
Lohmeyer

To:         Membership of X3T10

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

Subject:    Minutes of SPI-2/ESPC Study Group Meeting
            Colorado Springs, CO -- July 10, 1995


                                       Agenda

1. Opening Remarks

2. Approval of Agenda

3. Attendance and Membership

4. Low Voltage / Low Power Differential Interface [Ham/Aloisi]

5. TIA/EIA SP-3357 Low Voltage Differential Signaling (LVDS) Specification
   [Goldie]

6. Should low-speed signals be single-ended? [McGrath]

7. Resolution  of SPI-2 Project Proposal letter ballot comments (95-034r2)
   [Milligan]

8. Resolution  of ESPC Project Proposal letter ballot comments  (95-034r2)
   [Allan/Milligan]

9. Terminator Power Distribution [Aloisi/Ham]

10. Determining Differential vs. Singled-ended [Aloisi/Ham]

11. Propagation Delay Length Limit [Ham]

12. Pin-out Definitions [Ham/Lohmeyer]

13. SPI-2 Architecture [Ham]

14. EPI (formerly ESPC) Document Draft (Outline) [Ham]

15. Meeting Schedule

16. Adjournment




                              Results of Meeting

1.    Opening Remarks

John Lohmeyer, the X3T10 Chair, called the meeting to order at 9:05 a.m.,
Monday July 10, 1995.  He thanked Symbios Logic for hosting the meeting.

As is customary, the people attending introduced themselves and a copy of 
the
attendance list was circulated.  Copies of the draft agenda and general
information on X3T10 were made available to those attending.

2.    Approval of Agenda

The following items were added to the agenda.

   4. Low Voltage / Low Power Differential Interface [Ham]
  13. SPI-2 Architecture [Ham]
  14. ESPC Document Draft (Outline) [Ham]

The agenda was approved with the changes noted above.

3.    Attendance and Membership

 Attendance at study group meetings does not count toward minimum attendance
 requirements for X3T10 membership.  Study 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. Lawrence J. Lamers A# Adaptec, Inc.             ljlamers at aol.com
Mr. Wally Bridgewater  V  Adaptec, Inc.             wally at eng.adaptec.com
Mr. Dennis R. Haynes   P  Burr-Brown Corp.          haynes_dennis at bbrown.com
Mr. Louis Grantham     P  Dallas Semiconductor      grantham at dalsemi.com
Dr. William Ham        A# Digital Equipment Corp.   ham at subsys.enet.dec.com
Mr. Tom Coughlan       V  Digital Equipment Corp. 
  coughlan at star.enet.dec.co
                                                    m
Mr. Ralph O. Weber     A# ENDL Associate            roweber at acm.org
Mr. Stephen Holmstead  P  Hewlett Packard Co.       stephen at mail.boi.hp.com
Mr. George Penokie     P  IBM Corp.                 gop at rchvmp3.vnet.ibm.com
Mr. Duncan Penman      P  IIX Consulting            penman at netcom.com
Mr. Lance Packer       V  Motorola 
                 lance_packer at email.sps.mo
                                                    t.com
Ms. Shilpa Rad         V  Motorola                  shilpa at hcd.sps.mot.com
Mr. John Goldie        V  National Semiconductor    cjfgsc at tevm2.nsc.com
Mr. Todd Nelson        V  National Semiconductor    ctwnsc at tevm2.nsc.com
Mr. Peter Gossler      O  NSM Jukebox GmbH 
         73503.3467 at compuserve.com
Mr. Param Panesar      O  Pioneer Research
Mr. Skip Jones         P  QLogic Corp.              sk_jones at qlc.com
Mr. James McGrath      P  Quantum Corp.             JMCGRATH at QNTM.COM
Mr. Edward A. Gardner  A  Quantum Corp.             gardner at acm.org
Mr. Richard Uber       V  Quantum Corp.             duber at tdh.qntm.com
Mr. Gerald Houlder     A  Seagate Technology 
       Gerry_Houlder at notes.seaga
                                                    te.com
Mr. Greg Alvey         V  Solution Technology
Mr. John Lohmeyer      P  Symbios Logic Inc. 
       john.lohmeyer at symbios.com
Mr. Bruce Grieshaber   V  Symbios Logic Inc. 
       bruce.grieshaber at symbios.
                                                    com
Mr. Mark Jander        V  Symbios Logic Inc.        mark.jander at symbios.com
Mr. Frank Gasparik     V  Symbios Logic Inc. 
       frank.gasparik at symbios.co
                                                    m
Mr. Kevin Gingerick    V  Texas Instruments         4307725 at mcimail.com
Mr. Paul D. Aloisi     P  Unitrode Integrated       Aloisi at uicc.com
                          Circuits

28 People Present

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

4.    Low Voltage / Low Power Differential Interface [Ham/Aloisi]

Bill Ham presented a two-slide review of the current low-voltage low-power
differential interface.  He noted the hardware requirements implied by the
current plans.  Bill's slides can be found document 95-266r0.

Paul Aloisi described methods of making the multi-drop low-voltage low-power
differential bus needed for the SPI-2 proposals.  Paul's slides can be found
in document 95-269r0.  There was an extensive, highly technical, and 
detailed
discussion of how to design the electronic circuits, chips, and terminators
involved in low-power differential SCSI.  Significant participants in the
discussion were Kevin Gingerick, John Goldie, Wally Bridgewater, Bill Ham,
Larry Lamers, and Paul Aloisi.

Paul Aloisi and Bill Ham took an action item to build a hardware test rig 
from
which some waveform data can be taken.  Adaptec and Symbios Logic will be
modeling signal data and cable lengths.

5.    TIA/EIA SP-3357 Low Voltage Differential Signaling (LVDS) 
Specification
      [Goldie]

John Goldie reported that SP-3357 is approved unanimously.  One of the yes
votes had an attached comment.  The comment has been resolved.  The document
is expected to be published later this summer as TIA/EIA 644.  Some present
hoped that the TIA/EIA spec could be referenced by the SPI-2 document.
However, the differences appeared to be overwhelming that hope.  The major
difference is that the TIA/EIA document is point-to-point, whereas SCSI is
multi-drop.  This difference produces several corollary differences that
multiply to substantial problems.  It was agreed that referencing a standard
but attaching so many changes would not be practical.

John Lohmeyer asked about providing feedback to TIA/EIA that describes the
SCSI requirements.  John Goldie suggested that such communications could be
arranged.

6.    Should low-speed signals be single-ended? [McGrath]

Issues about the use of low-speed signals were discussed at length.  The
motivation is to reduce pin counts on protocol chips (one pin is saved for
each single-ended signal used).  Concerns were raised about backwards
compatibility with Fast-20.  Countervailing concerns were raised about 
optimal
SPI-2 performance and having a single unified solution for SPI-2.  No
conclusions were reached as more data is need about LVDS before the 
tradeoffs
are clear.

7.    Resolution of SPI-2 Project Proposal letter ballot comments (95-034r2)
      [Milligan]

The letter ballot passed 55:0:0:4.  One yes with comment was received.

Gene provided 5 letter ballot comments.  The study group recommended that 
all
comments except number 5 be accepted.  Acceptance of comment number 3 makes
the proposal in comment number 5 not applicable.

John said that a revised project proposal, reflecting the study group
recommendations, would be generated for plenary approval.

8.    Resolution of ESPC Project Proposal letter ballot comments (95-034r2)
      [Allan/Milligan]

The letter ballot passed 55:0:0:4.  Yes comments were received from Dal 
Allan
and Gene Milligan.

Dal raised the concern that ESPC looks like Enhanced SPC.  After a brief
discussion, the group recommended that X3T10 accept Dal's proposed acronym 
of
EPI.  Gene asked that the document name (not the acronym) contain SCSI, to
simplify document ordering.  As a result, the recommended name became SCSI
Enhanced Parallel Interface (EPI).

To address Gene's comment number 4, the group recommended that the word
"terminator" be added before the word "power" In item (g).  The group
recommended that Gene's comment number 11 be rejected, but the group also
recommends that the question of the applicability of ANSI's patent policy to
technical reports be raised with the X3 Secretariat.

In summary, the group recommended that 11 of Gene's 13 comments be accepted 
as
written, 1 comment be revised slightly, and 1 comment be rejected.

John said that a revised project proposal, reflecting the study group
recommendations, would be generated for plenary approval.

9.    Terminator Power Distribution [Aloisi/Ham]

Bill Ham presented the chart on termination power distribution.  The chart
originally was presented at the May study group meeting and appears in the
meeting minutes (95-209).  At the request of the group, Bill reviewed the
chart.  Bill described his plans to put the entire chart in EPI (formerly
ESPC) and parts of the chart in SPI-2.

10.   Determining Differential vs. Singled-ended [Aloisi/Ham]

Paul Aloisi, while reviewing document 95-269r0, displayed a revised method 
for
determining differential verses single-ended.  The concepts are 
fundamentally
the same as those discussed in May.  However, many of the details have 
changed
to accommodate the electronic realities.

11.   Propagation Delay Length Limit [Ham]

Bill Ham quickly reviewed his proposal to define cable length based on total
propagation delay.  Then, he noted that substantial delay is introduced by 
the
differential transceivers.  Kevin Gingerick confirmed Bill's observation and
stated that the nominal delay is 10 nanoseconds (20 nanoseconds per
transaction, because there are two transceivers involved in any 
transaction).
The group discussed whether to change the cable length formula or change the
point at which the total delay is measured.  Both choices had problems. 
 Bill
will study the issue further.

12.   Pin-out Definitions [Ham/Lohmeyer]

Bill Ham reviewed the pin-out list.  Larry asked about the allocation of pin
15, which he thought should be a ground.  Bill agreed.  Bill will prepare a
formal pin-out chart for SCSI low-power differential.

13.   SPI-2 Architecture [Ham]

Bill Ham presented his current thinking about the standards document 
framework
for the proposed SPI-2 document.  Bill noted the advantages of key SPI-2
proposals.  Bill's slides can be found in 95-267r0.

14.   EPI (formerly ESPC) Document Draft (Outline) [Ham]

Bill presented slides of his first draft of the EPI document structure.  A
couple of boiler-plate draft sections were reviewed and revised.  The 
majority
of the draft was an outline of the document contents.  Bill's use of an SFF
document as a reference was questioned.  Such a reference definitely would 
be
incorrect in a standard.  But, the usage in a technical report might be
acceptable.

Bill reviewed all the proposed sections (outline headings).  A few questions
were raised and addressed.

Bill proposed convening a study group to examine logical unit bridges and
their relationships to RAID models.  Unfortunately, the RAID experts were in 
a
High-Availability study group meeting across the hall.

15.   Meeting Schedule

Bill requested that a low-voltage differential driver/receiver/terminator
issues meeting be duly authorized.  John Lohmeyer (Symbios Logic) 
volunteered
to host the interim meeting in Denver.  August 14, 1995 was selected as the
date.  The next meeting of SPI-2/EPI Study Group will be September 11, 1995,
in Bedford, NH at the Sheraton Tara Wayfarer Inn (603-622-3766), hosted by
Digital Equipment Corp.

16.   Adjournment

The meeting was adjourned at 3:49 p.m. on Monday July 10, 1995.

 --
John Lohmeyer             E-Mail:  john.lohmeyer at symbios.com
Symbios Logic Inc.         Voice:  719-573-3362
1635 Aeroplaza Dr.           Fax:  719-573-3037
Colo Spgs, CO 80916     SCSI BBS:  719-574-0424 300--14400 baud




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