Subject: Response to Ballot comments

From: Will Hobbs <[email-masked]>
Date: Wed, 02 Aug 95 14:22:00 PDT

Text item: Text_1

To IBIS Members

Here are comments from Dr. Alan Williams of the University of Manchester, who 
provides valuable review of EIA documents.  Bob Ross drafted the response, and 
he and I have reviewed the comments, which are attached.  You are welcome to 
consider the comments and you may prefer a different response.  Please inform 
Bob and myself directly or reply through the reflector if you see any issues 
with the response.  We particularly want input from interested Voting Members 
and people who were closely involved in the writing of IBIS Version 2.1. Based 
on comments and possible revisions, we plan to discuss and vote on this document
at the August 11 Open Forum meeting.

Will Hobbs
Intel Corp., in cooperation with

Bob Ross
Interconnectix, Inc.

Response Document follows:

-----------------------------------------------------------------------------

Dr. Alan Williams
Dept. of Computer Science
University of Manchester
Oxford Road
Manchester M13 9PL
United Kingdom

Dear Dr. Williams:

On behalf of the EDA IBIS Subcommittee, thank you very much for your detailed 
review and valuable comments.  Our Committee response based on a review and vote
of approval at the IBIS OPEN FORUM meeting of August 11, 1995 is given as the 
attachment "EIA IBIS COMMITTEE RESPONSE TO UNIVERSITY OF MANCHESTER COMMENTS TO 
STANDARDS PROPOSAL NO. 3527.

Sincerely,

Will Hobbs
Chairman, EIA IBIS Open Forum

EIA IBIS COMMITTEE RESPONSE TO UNIVERSITY OF MANCHESTER
COMMENTS TO STANDARDS PROPOSAL NO. 3527

University of Manchester : 1
Editorial
Page 2 (first one i.e. Notice), Line 10 Delete Copyright symbol

Response: The approved version of EIA-656 will contain a copyright notice symbol
in compliance with EIA format conventions.

University of Manchester : 2
Editorial
Page 2 (second one i.e. Contents)
Correct the page numbers

Response: The page numbering will be corrected in compliance with EIA format 
conventions in the approved version of EIA-656.

University of Manchester : 3
Editorial
Page 1 (Preface, first paragraph, first line Add a noun after "(EDA)"

Response: The text will be corrected to read "The IBIS Open Forum, a group of 
some 34 electronic design automation (EDA) companies, semiconductor companies, 
and other interested organizations, ...".

University of Manchester : 4
Editorial
Page 1 (Preface), fifth paragraph, first line Delete "also" from "Forum also 
created"

Response: This change will be made as requested.

University of Manchester : 5
Editorial
Page 1 (Scope), second paragraph, third line
Change "With IBIS, vendors" to "Within the IBIS format, vendors"

Response: This change will be made as requested.

University of Manchester : 6
Editorial
Page 3, line 2
Change "12/9/94" to "9th December 1994"

Response: A change will be made to "August 22, 1995" to reflect the date of 
letter ballot conclusion and (hopefully) approval of the EIA version
of IBIS 2.1 and to differentiate it from any prior published IBIS Standards 
designated as Version 2.1

University of Manchester : 7
Editorial
Page 5, line 1
Delete "degrees"
Reason: "degrees" should only be used with Centigrade and Farenheit

Response: No change will be made.
Reason: We note that in the EIA Engineering Publication (1990) Style Manual for 
Standards of EIA, TIA, and JEDEC, EP-7, Appendix C (Abbreviations), page 26, 
both "degree Celsius" and "degree Fahrenheit" are listed as "Unit or Term". 
However, we will use the accepted terminology if this is in error.

University of Manchester : 8
Editorial
Page 5, line 3
Change "supplimental" to "supplemental"

Response: This change will be made as requested.

University of Manchester : 9
Editorial
Page 7, line 4  (Should be Page 6)
Change "These keywordsF arguments" to "The keyword arguments"

Response: This change will be made as requested.

University of Manchester : 10
Technical
Page 6, line 5
Change ", and be of any format" to ", and, apart from the Date, be of any 
format".
Reason: Although it is difficult to standardize the format and semantics of 
concepts such as a Disclaimer, the format of the Date should be standardized and
should be in UTC.  The example file illustrates this as the date is open to two 
possible interpretations: 12th of September 1994 and 9th of December 1994.  The 
exact meaning of the day will also vary according to the time zone.

Response: Some Editorial clarifications will be made.
Page 6, lines 4-6 will be changed (including comment 9) to read:
" Usage Rules:   The keyword arguments can contain blanks, and be of
any format.  The [Date] keyword argument is limited to a maximum of 40 
characters, and the month should be spelled out for clarity."
Page 6, line 15 will be changed from 12/9/94 to "August 22, 1995"
Page 27, line 51 will be changed from "December 9, 1994" to "August 22, 1995".

Reason: The syntax such as 12/9/95 has been used in all versions of IBIS files. 
While there may be an advantage to standardizing the date/time format, there 
really is not sufficient need to make it a requirement.  The [Date] keyword is 
optional, so data provided is informational.  Instead, A clarification comment 
and change of examples should be sufficient.

University of Manchester : 11
Technical
Page 7, line 4
Issue: It is not clear if the minimum <= typical <= maximum.

Response: No change will be made.
Reason: The IBIS standard does not apply rigid restrictions on most data, but 
does give guidance.  The example for the sub-parameters R_pkg, L_pkg, and C_pkg 
indicates that entries are placed in the "typ", "min" and "max"
columns by magnitude.  The expected entries for "typ", "min" and "max" columns 
for all keywords and sub-parameters are collected in the section NOTES ON DATA 
DERIVATION METHOD.  Paragraph 5 on page 31 would apply, for example, to the 
R_pkg, L_pkg, and C_pkg sub-parameters.

University of Manchester : 12
Technical
Page 7, lines 38 and 39
Change "If "NA" is in columns 4 through 6, the default packaging values must be 
used" to "NA cannot be specified for all three values in columns 4 through 6".
Reason: As currently specified, two alternative mechanisms are available for 
assuming the default values i.e. stating nothing or stating "NA NA NA".  In a 
standard, such multiple mechanisms are liable to lead to confusion.  In 
addition, the semantics of NA are subtly altered from "Not available" to "Take 
default".

Response: No change will be made.
Reason: While the point is valid, the semantics in most cases where "NA" is used
is "the data is not available, so an appropriate alternative is suitable."  In 
some cases the default alternative is explicitly specified,
such as with the [Package] sub-parameters.  In other cases, it is implicitly 
specified, such as with tdelay_typ.  In still other cases, another
column of data or processed data value is appropriate such as with NA entries in
"max" and "min" columns of VI tables and of VT tables.  The
simulator will act in an appropriate manner consistent with it's capabilities 
and the type of problem it is solving.  The redundant syntax "NA NA NA" and null
choices are already implemented in Version 1.1 parsers, in ibis_chk, in 
ibis_chk2 (under development), in commercial products, and in existing IBIS 
files.  There is not sufficient reason to exclude the redundancy at this time 
and violate the dedication to backward compatibility.

University of Manchester : 13
Editorial
Page 8, line 40
Change "terminator is connected" to "terminator is connected to"

Response. This change will be made as requested.

University of Manchester : 14
Editorial
Page 11, lines 35 and 36
Delete "the parser issues a warning and"
Reason: The specification of a transfer standard should not depend upon the 
functionality of a 'golden parser'.  If this phrase is intended to constrain the
functionality of an IBIS checker then this should be specified in a separate 
section, preferably in a separate document.

Response: No change will be made.
Reason: While reference to the parser has been argued as inappropriate,
an important exception is conveyed by the specific reference.  A violation of a 
stated requirement in this case is not considered serious enough that an error 
message is generated.  In previous Version 1.1 of IBIS, the requirement did not 
exist.  So for backward compatibility, this statement and this weaker treatment 
of an error condition is made.  Also, the parser has been viewed by some as a 
practical, defacto implementation of the standard.

University of Manchester : 15
Editorial
Page 11, lines 41 and 42
Delete: "the parser issues a warning and"
Reason: The specification of a transfer standard should not depend upon the 
functionality of a 'golden parser'.  If this phrase is intended to constrain the
functionality of an IBIS checker then this should be specified in a separate 
section, preferably in a separate document.

Response: No change will be made.
Reason: Same as response to comment 14

University of Manchester : 16
Editorial
Page 13, line 14
Change: "degree C" to "C"
Reason: See comment 7

Response: The change will be made to "degree Celsius". Reason: Same as response 
to comment 7

University of Manchester : 17
Editorial
Page 13, lines 41-46
Delete the paragraph
Reason: This paragraph appears to repeat information stated elsewhere. In 
addition its presence under the "GND Clamp Reference" keyword is confusing.

Response: This part of Other Notes will be deleted here as requested and 
restated in the [Voltage Range] keyword description, page 13:
"Other Notes:  If the [Voltage Range] keyword is not present, then all four
of these keywords described below must be present: [Pullup Reference], [Pulldown
Reference], [POWER Clamp Reference],
and [GND Clamp Reference].  If the [Voltage Range] is present, the other 
keywords are optional and may or may not be used as required.  It is legal 
(although redundant) for an optional keyword to specify the same voltage as 
specified by the [Voltage Range] keyword."

University of Manchester : 18
Editorial
Page 16, lines 8-13
Delete the paragraph
Reason: See comment 15

Response: No change will be made.
Reason: There are few data restrictions on IBIS.  However, the issue of 
monotonic data is very important as it relates to the algorithms used to process
the IBIS data.  While reference to the parser has been argued as inappropriate, 
an exception is made here because of the need to identify non-monotonic data.

University of Manchester : 19
Editorial
Page 22, line 36
Change: "in all .ibs files" to "in all .ibs and .pkg files"

Response: This change will be made as requested.

University of Manchester : 20
Editorial
Page 22, line 46
Change "in all .ibs files" to "in all .ibs and .pkg files"

Response" This change will be made as requested.