================================================================================ IBIS INTERCONNECT TASK GROUP http://www.ibis.org/interconnect_wip/ Mailing list: ibis-interconnect@freelists.org Archives at http://www.freelists.org/archive/ibis-interconn/ ================================================================================ Attendees from December 18, 2019 Meeting (* means attended at least using audio) ANSYS Curtis Clark Cadence Design Systems Bradley Brim Intel Corp. Michael Mirmak* Keysight Technologies Radek Biernacki Mentor, A Siemens Business Arpad Muranyi* Micron Technology Justin Butterfield*, Randy Wolff* SiSoft Walter Katz*, Mike LaBonte Teraspeed Labs Bob Ross* Michael Mirmak convened the meeting. No patents were declared. Justin Butterfield took minutes. Review of Minutes: - Michael called for review of the minutes from the December 11, 2019 meeting. Randy Wolff moved to approve the minutes. Walter Katz seconded. The minutes were approved without objection. Review of ARs: - Walter to send out EMD draft 27. - Michael reported this was done. Opens: - Michael asked if the change from pin list to terminal is done. Walter replied he has defined some of these terms and changed the text where he thought appropriate. - Michael noted we still need to have the "what does connected mean" discussion. - Bob Ross commented we should consider organizing the sections a little differently. We do not want too many details in the introduction, but we do want to introduce some of the files. Michael asked if the rest of the IBIS specification follows this. Bob noted some of the sections are different. Walter noted he followed the structure of the EBD section, and that this is an editorial issue. Michael agreed and noted, if we are not consistent, we will need to review the entire IBIS specification. Bob commented it might be better for follow the format of the Interconnect section. Walter suggested EBD and EMD could be separate documents, and this should be discussed in an Editorial group meeting. Michael suggested this should be discussed in the IBIS Open Forum. Bob noted separating the specifications would result in a lot of overlap. - Bob commented there are some syntactical rules that may not be documented, and we may need some additional review of these. Michael asked if there were examples of this. Bob noted there are some differences between Interconnect and EMD. In EMD, we can have multiple designator interfaces. Walter suggested to submit the issues in writing. Bob stated he is not opposed to submit this as a BIRD to get a number, but there is still significant work to be done. Michael agreed to get the comments in writing. EMD Draft 27 review: Walter showed the changes from draft 26. He changed "module pin_names" to "EMD pin_names". On page 14, Walter added text to define designator terminal and EMD terminal. Bob asked if this applies to rail or IO pins. Michael asked if we define the rail pins and I/O pins before this section. Walter replied these are defined, and we are defining a terminal. He noted a terminal only applies when you are talking about a model. Bob asked what section this is in. Walter replied this is under the [EBD Group] keyword. These are the rules relating to the models in the EMD group. Walter noted, on page 16, "module" was changed to "EMD", there are also changes from "modules" to "pins". There are similar changes on pages 22 and 23. Bob suggested, on page 23, to add A_gnd to the Terminal_type list. Michael asked if we need any diagrams to show the physical meaning of pins, I/Os, rails, etc. Randy asked if a picture of a DIMM module would be helpful. Bob asked if this would be a board or a stacked die. Michael suggested one of these would be a big addition. Walter commented this is intended to replace the EBD for DIMMs, and a picture of DIMM routing would be useful. Randy will look into adding a picture of DIMM routing [AR]. Walter suggested it would be good to look at an RDIMM with a Register and PLL. Bob noted we can route the I/O signals from the designator to the EMD interface or to another designator. Walter agreed this is an important use case of EMD. Randy asked if it would be helpful to look at a case with a series resistor. Walter suggested the resistor could be modeled inside the EMD model or as a separate designator. Bob suggested the connections should be clearly documented, and he suggested to not connect these with a designator. Michael noted the term "connection" needs to be defined in IBIS. Bob asked if we do not have a syntax that automatically shorts signals of the same name at the same interface of the same designator. Walter replied there is no mechanism to short signals of the same name at a given interface. Bob stated, at the EMD Set level, we might have two IO pins with the same name. He asked how to handle this case. Walter stated this is not the case for I/Os. Connectivity is not determined by the signal_name. Bob commented there is an association issue. Walter noted they could be be connected, which is defined in the email proposal he sent out. There are good connections and not good connections. Bob commented there are Aggressor_Only issues, where it is possible to determine that an aggressor tag of one I/O pin is added at any of the designator interfaces. This propagates to all of the designators. In interconnect, we determined this with pin_names. We can route an I/O through different designators, and tagging one as a aggressor would tag them all. Walter suggested that the software can determine all of the connections and extended nets. Randy asked what is the case Bob is worried about. Bob replied, in the EMD file, we have an Aggressor_Only that is based on the EMD designators with the same signal_name. This could be an issue when we have nested EMDs and multiple interfaces. Walter stated the signal_names would all be connected. Bob stated they would be shorted. Walter noted you would have terminals at each interface, and this is not something people would do. Michael asked if this is a specific case and if it needs to be addressed in the BIRD. Walter suggested we are using the common definitions of connected and shorted. Bob will look for some examples to show the issue. Walter will send out draft 28 [AR]. He intends, after the next meeting, to have a BIRD ready to submit to the IBIS Open Forum. He suggested for comments to be submitted in writing. Michael suggested to have a tracking list of comments. Bob suggested, on page 25, to add A_gnd to the Terminal_type list and to Table 41. Next Meeting: The next meeting will be January 8. Randy moved to adjourn. Walter seconded. The meeting adjourned without objection. ================================================================================ Bin List: EMD Comments to be Resolved: IBIS-ISS Parser: - IBIS-ISS parser scope document