Next Generation SPI WG Minutes

chris smith tardis at
Thu Mar 23 10:32:53 PST 1995

I got this, I don't know why?????

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>From: "Lohmeyer, John" <JLOHMEYE at>
>To: SCSI Reflector <scsi at>
>Subject: Next Generation SPI WG Minutes
>Date: Fri, 17 Mar 95 18:42:00 MST
>Message-ID: <2F6A3AA3 at>
>Encoding: 285 TEXT
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>Minutes of Next Generation SPI Working Group in Newport Beach, CA 
>Accredited Standards Committee
>X3, Information Technology
>                                                   Doc. No.: X3T10/95-172r0
>                                                       Date: March 17, 1995
>                                                    Project:
>                                                  Ref. Doc.:
>                                                   Reply to: John Lohmeyer
>To:                Membership of X3T10
>From:              Ralph Weber, Secretary X3T10
>                   John Lohmeyer, Chair X3T10
>Subject:           Minutes of X3T10 SCSI SPI Futures Ad Hoc Meeting
>                   Newport Beach, CA -- March 6, 1995
> ----------------------------------------------------------------------------  
> --
>                                       Agenda
>1. Opening Remarks
>2. Attendance and Membership
>3. Next-Generation SPI
>4. Adjournment
> ----------------------------------------------------------------------------  
> --
>                                 Results of Meeting
>1.    Opening Remarks
>John Lohmeyer, the X3T10 Chair, called the SPI the meeting to order at 9:10 
>He thanked Skip Jones of QLogic for arranging and hosting the meeting.  The
>meeting was held at the Hyatt Newporter, Newport Beach, CA.
>As is customary, all those present introduced themselves.  John noted that 
>meeting is an ad hoc meeting of the X3T10 committee.  John reminded everyone 
>the X3T10 rules and noted that votes taken at this meeting (if any) have no
>binding effect on X3T10.
>2.    Attendance and Membership
>Attendance at working group meetings does not count toward minimum 
>requirements for X3T10 membership.  Working group meetings are open to any
>person or organization directly and materially affected by X3T10's scope of
>The following people attended the meeting:
>         Name          S        Organization         Electronic Mail Address
> ---------------------- -- ------------------------- 
> -------------------------
>Mr. Ron Roberts        A  Apple Computer            rkroberts at
>Mr. Dennis R. Haynes   P  Burr-Brown Corp.          haynes_dennis at
>Dr. William Ham        A# Digital Equipment Corp.   ham at
>Mr. Ralph O. Weber     A# ENDL Associate            roweber at
>Mr. Zane Daggett       O  Hitachi Cable 
>            74354.2576 at
>                          Manchester,Inc
>Mr. Dean Wallace       P  Linfinity Micro
>Mr. Peter Gossler      O  NSM Jukebox GmbH 
>         73503.3467 at
>Mr. Skip Jones         P  QLogic Corp.              sk_jones at
>Mr. Doug Prins         A# QLogic Corp.              d_prins at
>Mr. Ting Li Chan       A  QLogic Corp.
>Mr. James McGrath      P  Quantum Corp.             JMCGRATH at QNTM.COM
>Mr. Gene Milligan      P  Seagate Technology 
>       Gene_Milligan at notes.seaga
>Mr. Stephen G. Finch   P  Silicon Systems, Inc.     5723283 at
>Mr. Erich Oetting      P  Storage Technology Corp. 
> Erich_Oetting at
>Mr. John Lohmeyer      P  Symbios Logic Inc.        john.lohmeyer at
>Mr. Paul D. Aloisi     P  Unitrode Integrated       Aloisi at
>                          Circuits
>Mr. Tak Asami          A  Western Digital           asami at
>                          Corporation
>17 People Present
>Status Key:  P    -  Principal
>             A,A# -  Alternate
>             O    -  Observer
>             L    -  Liaison
>             V    -  Visitor
>3.    Next-Generation SPI
>Paul Aloisi reminded the group of the list of potential SPI futures topics:
>    1. Incremental and/or replacement standards documents
>    2. Connectors (32-bit, ..., high-density)
>    3. Higher speeds
>    4. Lower voltage
>    5. Lower power
>       a. termination
>       b. silicon power for differential
>    6. Hot swap (tm?) ... further definition
>    7. System considerations
>    8. Ease of use
>    9. Cable specifications
>   10. Backplane specifications
>   11. Alternate topologies (bridges, routers)
>   12. Enhanced error detection/correction
>   13. Adaptive performance
>   14. Fair access
>   15. TERMPWR distribution
>   16. Shield effectiveness
>   17. Longer cable lengths
>   18. High density external connector
>John noted that a significant question is whether the next SPI document will 
>a replacement for or addition to the existing SPI document.
>John noted that Jim McGrath is advocating bridges and routers, particularly 
>transaction processing systems.  Steve Finch raised concerns about low power
>differential (which caused the minutes to divide item 5 into a and b).  The
>problem with low-power differential is backwards compatibility.  Several
>electrical issues including termination, cable impedance, and common mode
>voltages prevent backwards compatibility in low-power differential.
>Bill Ham asked for volunteers to work on low-power differential.  He did not
>get a rousing show of support.  John did note that a repeater design might 
>the interoperability solution for low-power differential.  Ralph postulated
>that backwards compatibility is not really an issue.  The gains might be
>sufficient to get people to make a non-compatible change in hardware.
>During a discussion of cable length, it was noted that arbitration rules 
>to change to permit cable lengths much in excess of 25 meters.  The signal
>settling times must be increased to allow arbitration signals to transit the
>longer cables.
>The meeting next turned to issues of impedance and wire gauge.  Higher
>impedance is needed to improve signal quality.  Thinner wires (larger wire
>gauges) make the cables easier for people to handle and increase impedance.
>Bill noted that the limits are lack of silicon and a defined termination
>scheme.  The other key issue is accepting the choice for no backwards
>Paul Aloisi presented a proposed differential termination circuit that John,
>Bill, and Paul discussed in detail.  The circuit reduced the d.c. power
>consumed by differential drivers without increasing the a.c. impedance.
>Bill turned the discussion to 32-bit wide operation.  The main problems 
>to be the cable and connector(s) required.  John noted that some of the 
>proponents were planning on backplane implementations, which would not have
>cable problems.  It was noted that 32-bit cables cannot accept 32 devices, 
>to loading problems.
>Bill suggested adding "Reserved line definition" as a SPI futures topic 
>Bill suggested that at least some reserved lines would be needed for 
>terminator power.
>Eventually, Bill volunteered to lead a discussion to summarize the ideas
>expressed.  With Bill's help, the group generated the following list of 
>for SPI-of-the-future:
>   - + performance parity with differential
>       ++ length, device count, speed
>     + cost parity with single ended
>     = Single chip differential
>   - Higher peak bandwidth
>   - New devices capable of operating either
>     low-power differential, or single-ended
>     (a.k.a. backwards compatibility with old single-ended)
>   - Backwards compatibility with old differential
>     + cables, connectors, old devices the same (terminators different)
>     + message protocol compatibility
>     + arbitration protocol compatibility
>Based on the above goals list, the group developed this following list of 
>items as the core focus for SPI-2:
>   - Low power chips
>   - Alternate differential termination
>   - 32-bit (just how compatible is it?)
>   - Fast 40
>  Notes:
>     - Bridges and repeaters are still valid
>     - Smaller cables/connectors are ok
>     - Status bus should still be compatible (if used)
>Jim McGrath noted the need for a bus extender focus.  Bill and Jim agreed 
>the bus extender focus could be undertaken as a separate study project.  Jim
>felt that this is appropriate, because work on standards enhancements for 
>extenders is a short-term work project.
>Jim gave a presentation describing the needs for bus extenders.  He also 
>the basic mechanisms that are needed for bus extenders.  Jim and Bill 
>the details of the electrical needs for bus extenders.  In effect, Jim's bus
>extender needs can be met by publishing a spreadsheet developed by John for
>setting bus lengths based on various timing parameters.
>Bill, Jim, and John agreed that the best format to publish the needed
>information is a technical report.  A project proposal must be created for 
>bus extender information technical report.  Jim will create a project 
>for forwarding later this week.  John will provide Jim with a boiler-plate 
>for generating the project proposal.  (Note: These two actions did not 
>so the project proposal will be generated later.)
>In the process of discussing Jim's other desire for more than bus-width 
>of devices per bus, the group added mechanisms for this to the core features
>The group discussed the entire list of projects.  Marking those that cannot
>have a proposal ready by July and assigning persons to prepare proposals for
>the others.
>The marked-up list thus produced was:
>        1. Incremental and/or replacement standards documents
>    x   2. Connectors (32-bit, ..., high-density) [McGrath]
> a  +   3. Higher speeds [*bundled with 5b]
> b  +   4. Lower voltage [Aloisi]
>        5. Lower power
> b  +      a. termination [Aloisi]
> a  +      b. silicon power for differential
>                                        [Aloisi/Gingerick/Jones/Symbios/Ham]
> e  +   6. Hot swap (tm?) ... further definition [Aloisi/McGrath/Ham]
>    x   7. System considerations
>    x   8. Ease of use
> b      9. Cable specifications [*bundled with 15*]
>    x  10. Backplane specifications
> c  +  11. Alternate topologies (bridges, routers) [Ham/McGrath/Lohmeyer]
>    x  12. Enhanced error detection/correction
>    ?  13. Adaptive performance [Lohmeyer]
>    ?  14. Fair access [Penman]
> b  +  15. TERMPWR distribution [Ham]
> d  +  16. Shield effectiveness [Ham]
> c  +  17. Longer cable lengths {TechReport} [McGrath/Lohmeyer/Ham]
> d  +  18. High density external connector [SFF]
>    ?  19. Reserved line definition [SFF]
> a  +  20. >16 devices addressable on the same logical bus [McGrath]
> a  +  21. Alternate differential termination [Aloisi]
> a High-Performance Server SPI
> b Portable SPI
> c Extended Topologies SPI
> d External Connections SPI
> e Hot Plugging
>    + paper expected by July
>    ? paper may be ready by July
>    x no paper ready by July
>4.    Adjournment
>The meeting was adjourned at 5:30 p.m. on Monday March 6, 1995.

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