Minutes of SPI-2 Working Group - June 6-7, 1996

Lohmeyer, John JLOHMEYE at cossymwest.co.symbios.com
Sun Jun 9 09:44:00 PDT 1996

* From the SCSI Reflector, posted by:

Minutes of SPI-2 Working Group - June 6-7, 1996  X3T10/96-189r0

Accredited Standards Committee*
X3, Information Technology
                                              Doc. No.: X3T10/96-189r0
                                                  Date: June 7, 1996
                                               Project: 1142-D
                                             Ref. Doc.:
                                              Reply to: John Lohmeyer

To:       Membership of X3T10

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

Subject:  Minutes of SPI-2 Working Group - June 6-7, 1996
          June 6-7, 1996 -- Colorado Springs, CO


1. Opening Remarks

2. Approval of Agenda

3. Attendance and Membership

4. SPI-2 Document Strategy [Lamers/Ham]

5. LVD Topics
  5.1 Voltage Mode and Slew Rate Test Data (96-187r0) [Ham]
  5.2 LVD SCSI Driver Specification Presentation (96-145r0) [Moore]
  5.3 Standing Waves [Bridgewater] {July meeting}
  5.4 Transmission Line Model (96-___r0) [Gingerich]
  5.5 SPI-2 Document Review (X3T10/1142D) [Ham]
  5.6 Deskew Delay () [Moore]
  5.7 Fast-80 () [Milligan]
  5.8 Hot Plugging () [Bridgewater]

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

7. Summary of Meeting Results [Ham]

8. Meeting Schedule

9. Adjournment

                          Results of Meeting

1.   Opening Remarks

John Lohmeyer, the X3T10 Chair, called the meeting to order at 9:00
a.m., Thursday June 6, 1996.  He thanked Symbios Logic for allowing
him to host 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:

5.6  Deskew Delay () [Moore]
5.7  Fast-80 () [Milligan]
5.8  Hot Plugging () [Bridgewater]
6.   High-Voltage Differential Fast-40 (96-190) [Gingerich]

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

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. Richard Moore      V  Adaptec, Inc.           richard_moore at corp.
Mr. Louis Grantham     P  Dallas Semiconductor    grantham at dalsemi.com
Mr. Siegfried Schmalz  V  Dallas Semiconductor    schmalz at dalsemi.com
Dr. William Ham        A# Digital Equipment Corp. ham at subsys.enet.dec.com
Mr. Dean Wallace       P  Linfinity Micro   
        75671.3443 at compuserve.com
Mr. Wayne E. Werner    O  Lucent Technologies     wew at aluxpo.lucent.com
Mr. Brent Mulholland   V  Maxtor Corp.            bmulholl at maxtor.com
Mr. Edward A. Gardner  P  Ophidian Designs        gardner at acm.org
Mr. Ting Li Chan       A  QLogic Corp.            t_chan 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. Dave Guss          P  Silicon Systems, Inc.   dave.guss at tus.ssi1.com
Mr. John Lohmeyer      P  Symbios Logic Inc.   
     john.lohmeyer at symbios.com
Mr. Kevin Bruno        V  Symbios Logic Inc.      kevin.bruno 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. Paul D. Aloisi     P  Unitrode Integrated     Aloisi at uicc.com

20 People Present

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

4.   SPI-2 Document Strategy [Lamers/Ham]

John Lohmeyer reviewed the results of the plenary motion in May to
consolidate all of the SCSI physical layer into the SPI-2 document
(SPI, Fast-20, LVD, and some of the SCSI-2 connector documentation).
Larry Lamers, Bill Ham, and John had reviewed this decision with Harry
Mason, the STA Chairman.  The group was concerned that this direction
ignored the STA request to stabilize LVD technology quickly.
Furthermore, the combined document probably should also include the
contents of SIP to avoid several documentation problems (i.e., SCAM
and Transfer Period negotiation).

The obvious solution to the conflicting needs is to develop two
standards: one would document LVD technology and the other would
document the entire SCSI parallel physical layer.  The issue of
selecting names for the two projects was more difficult.  Harry Mason
indicated that STA had already promoted LVD as the technology that
enables Ultra2 SCSI and STA has told a lot of people that LVD is
documented in SPI-2.  Therefore he preferred that the current SPI-2
project not change names.  He was less concerned over what the second
project was called.

John had drafted a new project proposal for the combined document that
he called "SCSI Unified Parallel Requirements (SUPR)".  The SUPR
document would contain the entire SCSI parallel definition up to and
including SIP.  This project would also attempt to resolve the
differences between SCSI-2, SPI, Fast-20, and the current LVD work
(e.g., cable impedance specification, driver/receiver switching
thresholds, slew rate specifications, etc.)

Assuming X3T10 agrees, the current SPI-2 document (Project 1142-D)
would continue on its previous path and be forwarded as soon as
possible.  The relationship of these projects is shown pictorially

  <figure omitted from ASCII file>

There was some discussion about the scope of the SPI-2 project.  Does
SPI-2 incorporate all new physical items (e.g., High-Voltage
Differential at Fast-40, new connectors, terminator power
distribution, etc.) or only define the LVD technology for SCSI?  Bill
Ham wanted LVD, Universal, existing de-facto connectors, and
terminator power distribution.  Kevin Gingerich wanted to include a
high-voltage differential option.  The group tentatively agreed to all
of the above.

5.   LVD Topics

     5.1  Voltage Mode and Slew Rate Test Data (96-187r0) [Ham]

Bill Ham presented test data using voltage mode drivers that he had
built from high-speed op amps.  There was some concern expressed over
whether the op amps were really acting as voltage mode drivers.  Bill
responded that the signal amplitude did not change when he removed the
resistors by the drivers and therefore the drivers must be in voltage

Bill's conclusion from his testing was that the configuration rules do
not seem to be dependent on the type of driver.  Richard Moore stated
that the voltage mode drivers could have a more relaxed test circuit
to allow for smaller area drivers.  Is the test circuit correctly
testing what is needed?  No conclusion was reached on this point;
Richard plans to prepare a written proposal.

Because the signals tend to lose their high-frequency content as they
pass devices (and thus have increasing slope), the precision on the
degree of asymmetry of the drivers is important to maintain the timing
budget.  Bill was not sure how well Figure 22 defines the asymmetry
requirements until it was noted that a bias is built into the V1 and
V2 voltage levels in the test circuit.  Figure 22 needs to be more
clearly labeled to tie it to Table 11.  A note to indicate that the
bias is already built in by virtue of V1 and V2 in the test circuit
may also be needed.

     5.2  LVD SCSI Driver Specification Presentation (96-145r0) [Moore]

This item was covered with the material included in rev 8.  Richard
asked that an item be included on the next agenda for a test circuit
considerations for voltage mode drivers.

     5.3  Standing Waves [Bridgewater] {July meeting}

Wally requested that the discussion of standing waves be deferred
until the July meeting.

     5.4  Transmission Line Model (96-___r0) [Gingerich]

Kevin said he had nothing new.

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

Kevin Gingerich presented a revised scope that was accepted with some

There was some discussion about the term "universal".  With the
addition of HVD should universal be changed to dual-mode or multi-mode
or something else.  The group agreed to leave the term alone since it
has already been widely advertised.

Paul Aloisi proposed a procedure for determining driver type.  During
the discussion minor changes were made.  The resulting procedure was:

1) power-on in high impedance state;
2) delay 0.5 seconds and look at the DIFFSENSE signal;
3) set the driver mode to LVD, SE, or disabled/HVD based on the
voltage level present on the DIFFSENSE signal.

If the device is using an SCA-2 connector, then step 2 should be
started after the mated-1 and mated-2 signals are connected.

Bill Ham lead a page-by-page review of SPI-2 revision 8.  See revision
9 for the results.

     5.6  Deskew Delay () [Moore]

Richard Moore stated that the deskew delay is not specified for Fast-
40.  Most events that use this value are asynchronous so the 15 ns
value of Fast-20 is acceptable.  However, when doing data transfers a
shorter time would be useful for initiators running at higher clock
speeds.  The recommendation was to include a 6 ns deskew delay for
Fast-40.  The Fast-80 number will be visited at the next meeting.

     5.7  Fast-80 () [Milligan]

Should the scope of the working draft include Fast-80?  The
configuration rules for Fast-80 need to be determined; the intersymbol
interference will cause changes from the rules for Fast-40.

Gene suggested a uniform set of configuration rules and a SPI-3 that
would have balanced encoding.  Gene stated that the same configuration
rules need to apply to Fast-40 and Fast-80 because that is what the
marketing folks have requested.

The straw poll was evenly divided on leaving in or removing the Fast-
80 specifications until Bill Ham has data in July, so status quo won.

     5.8  Hot Plugging () [Bridgewater]

Wally Bridgewater requested a re-confirmation that the case 4 hot-
plugging will be excluded for LVD transceivers.  While this is a
question best answered by STA, it did prompt a lengthy discussion
about hot plugging and what is the process a device uses to determine
if it should use SE or LVD drivers.  A wait period of x seconds is
needed to make a rational decision.  An annex may be needed to deal
with the system issues of transitioning the bus during power-on and
hot-plugging situations.

A key point made during the discussion was that no discontinuity in
termination is allowed for hot plugging cases 2 and 3.  Thus attempts
to change driver modes (e.g., by hot plugging a single-ended drive
into an LVD bus) are illegal and may result in problems.

John agreed to ask the STA group how important case 4 hot plugging is
to the LVD market.  Without significant changes, case 4 cannot be
supported by LDV.

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

Kevin Gingerich stated that high-voltage differential is feasible
(although challenging) at Fast-40 speeds.  He proposed that this
option be added to the SPI-2 document.

Gene Milligan stated that hot-plugging is a concern with differential;
Bill Ham replied that the glitch is insignificant and HVD is more
forgiving than LVD.

There are some evolutionary changes needed; the timing parameters are
the same, but an asymmetrical driver is needed.  The consensus was to
include the HVD specifications.

7.   Summary of Meeting Results [Ham]

8.   Meeting Schedule

The next meeting of SPI-2 / EPI Working Group will be Monday July 15
in Colorado Springs, CO at the Red Lion Hotel (719-576-8900) hosted by
Symbios Logic.  Another meeting of this group is scheduled for August
13-14, 1996 in Redwood City, CA hosted by the SCSI Trade Association
(STA).  The group suggested that October and November meetings be held
with X3T11 on Thursday (October 10th and December 5th).

9.   Adjournment

The meeting was adjourned at 3:00 p.m. on Friday June 7, 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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