[IBIS] Recent ibischk4 Version 4.2.1 Improvements

To IBIS Users:

The recently released ibischk4, version 4.2.1 parser has some
significant improvements and changes:

1. Warnings for non-monotonic tables are now based on summation
of I-V tables tests for each mode (driving, non-driving)  The
tests now include Submodel Dynamic_clamp tables.  Individual
non-monotonic tables are now reported as Notes (reduced from
Warnings).  The tests are applied in the same manner for
all [IBIS Ver] levels from 2.0 through 4.2.

- Impact:  Fewer Warning messages but more information about
non-montonic in a consistent manner for all levels.

2. The [Receiver Thresholds] tests have been downgraded to
be more permissive and upgraded to be more comprehensive.
Single-ended and differential subparameters are now permitted
without any Warnings.  Error reports for omitted or included
information have been reduced to Warnings.   The reason for
these changes is that the combination of [Diff Pin], [Model Selector]
along with [Receiver Thresholds] under [Model] produced some
unexpected configurations that were incorrectly checked.

- Impact: Models (such as DDRII with selectable on die
terminators) that document thresholds according to JEDEC
standards will probably report many Warning messages with
ibischk4 version 4.2.1.  Previously with Version 4.2.0, they
might have passed with 0 Errors and 0 Warnings.  These models
probably have incomplete differential threshold information
under certain [Diff Pin] and [Model Selector] combinations.

3. A new -caution flag is introduced to support some additional
model quality checking.  This test will apply for all [IBIS Ver]
levels from 2.0 through 4.2 and for all file types .ibs,
.pkg, and .ebd.

Impact: The Quality committee in particular wants to add more
tests for reasonable data.  Because there might be cases where
unusual entries are correct and intended, a Warning would not be
appropriate.  More Caution tests are expected to help the
model developer catch bad data.

4. The Warning message for having an Open* Model_type (e.g,
Open_drain, Open_source, etc.) and an incorrect [Pullup] or
[Pulldown] table with non-zero entries is now elevated to
an Error message.

Impact: Files with Open* models and unexpected tables with
non-zero entries will produce Errors instead of Warnings
because the information is contradictory.  Either the
Model_type is wrong or the data is wrong.

--

There are other changes, but these changes improve the ibischk4
functionality and correct some checking errors and omissions.

Bob
-- 
Bob Ross
Teraspeed Consulting Group LLC     Teraspeed Labs
121 North River Drive              13610 SW Harness Lane
Narragansett, RI 02882             Beaverton, OR 97008
401-284-1827                       503-430-1065
http://www.teraspeed.com           503-246-8048 Direct
bob@teraspeed.com

Teraspeed is a registered service mark of Teraspeed Consulting Group LLC


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