[ibis-macro] Re: IBIS-AMI Model Portability
- From: <colin_warwick@xxxxxxxxxxx>
- To: <ibis-macro@xxxxxxxxxxxxx>
- Date: Sun, 1 May 2011 14:40:13 -0600
Hi Todd,
I'd say the first model is giving the wrong answer, because RX_Noise was
clearly important (otherwise why bother adding it?) and now it's been deleted.
This similar to the problem with models that have compliant syntax and
proprietary semantics. They run in a simulator that lack the proprietary
extension, but they give the wrong answer, which is worse than not running at
all.
On the bigger issue, I know there are good intensions behind the velocity that
they bring, but the obvious danger (if models with proprietary extensions
become widespread) is the standard gets hijacked and the proprietary extension
becomes a de facto standard. That benefits the one EDA company that controls
the extension, but it's to the detriment of the other Forum contributors: the
other EDA companies, all the IC model producers, and all the OEM model
consumers.
SPICE models started off with Berkeley SPICE, then we had vendor-specific
SPICE dialect models, then the antithesis of portability: vendor-encryption-key
SPICE models.
I guess Syed's point is he wants to avoid that fate for IBIS.
FWIW, IMHO, my $0.02 etc...
-- Colin
From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx]
On Behalf Of Todd Westerhoff
Sent: Saturday, April 30, 2011 1:13 PM
To: ibis-macro@xxxxxxxxxxxxx
Subject: [ibis-macro] Re: IBIS-AMI Model Portability
Scott,
Thanks for the feedback.
What happens if we make two models from the original model (let's use the
RX_Noise case)
1. The first model deletes the RX_Noise parameter (would a comment be
acceptable?)
2. The second model contains the RX_Noise parameter as originally proposed
Would you agree that the 1st model had a portability rating of 3, while the
second model had a portability rating of 0?
Todd.
________________________
Todd Westerhoff
VP, Software Products
SiSoft
6 Clock Tower Place, Suite 250
Maynard, MA 01754
(978) 461-0449 x24
twesterh@xxxxxxxxxx<mailto:twesterh@xxxxxxxxxx>
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From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx]
On Behalf Of Scott McMorrow
Sent: Saturday, April 30, 2011 12:57 PM
To: ibis-macro@xxxxxxxxxxxxx
Subject: [ibis-macro] Re: IBIS-AMI Model Portability
Todd
I'd disagree with your assertion: " ... that Model_Specific/Info parameters
would work without the need for a model "compatibility mode". It depends on
how you define work. If "work" is defined to be that the results are identical
in all simulators which use the model, then in no case does the parameter work,
unless the meaning of the parameter is well-documented and agreed upon. This
is the purpose of a specification. Guessing correctly does not count. If it
ain't in the specification, in my option, that specific function is not
portable. The remainder of the model may be compatible and portable, which is
a nice thing to have, but the model specific part is not, and does not achieve
the model maker's intention. Other EDA vendors may choose to make a decision to
support the parameter through a custom process, but that doesn't change the
fact that the parameter is not portable, and does not "work" in a simulator
that adheres strictly to the IBIS specifications and BIRDS.
I contend that the following is a good operational definition of work - "That
all simulators obtain the same result based on knowledge obtained on how to
process the parameter from approved IBIS specifications and BIRDS."
I'd agree with regards to your portability rating, which is different than your
introductory statements. Your Rx_Noise parameter gets a portability rating of
0. All other standard parameters and functions within the model get a rating
of 3.
Scott
Scott McMorrow
Teraspeed Consulting Group LLC
121 North River Drive
Narragansett, RI 02882
(401) 284-1827 Business
(401) 284-1840 Fax
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On 4/30/2011 12:29 PM, Todd Westerhoff wrote:
3. If the EDA tool does not understand RX_Noise and has no equivalent
simulator-specific noise feature, then the data is simply ignored, and the
simulator proceeds as it would have if the model had not included a RX_Noise
parameter at all. Nothing wrong with that, in our opinion.
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