[ibis-macro] Re: Making IBIS responsive to the modeling needs of the industry ... new keyword [Specification]
- From: "Walter Katz" <wkatz@xxxxxxxxxx>
- To: <Arpad_Muranyi@xxxxxxxxxx>, "'IBIS-ATM'" <ibis-macro@xxxxxxxxxxxxx>
- Date: Fri, 5 Dec 2008 14:27:53 -0500
Arpad,
Thanks for getting this cleared up. My proposal requires pointed to a
document (sorry for the word file which led to the confusion). It needs to
be a "document" because pointing to a section of a spec is not an easy thing
to do without putting together human readable words. Having a name for the
spec, as you say, allows EDA tools to point to their implementation of that
spec in their internal language.
I would hope that we can convince JEDEC and other industry standard groups
to help us by creating "Standard" names for these "Standard" specifications.
Walter
-----Original Message-----
From: ibis-macro-bounce@xxxxxxxxxxxxx
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Muranyi, Arpad
Sent: Friday, December 05, 2008 2:12 PM
To: IBIS-ATM
Subject: [ibis-macro] Re: Making IBIS responsive to the modeling needs of
the industry ... new keyword [Specification]
Walter,
I think the disagreement we have comes from two different things
we were talking about. Now I understand that you were talking
about pointing to an industry spec, but not for the purpose of
parsing and reading the document to extract the numbers from it,
but so that the EDA vendor can pre-program the simulator with the
numbers found in those specs, and when the IBIS file points to a
spec like that, the tool could identify which pre-programmed
number set to use for the purpose they are there for.
What I was thinking about was different. I was thinking that the
[Specification] keyword would point to a "data file" that the user
or model maker writes to tell the simulator through the IBIS file's
[Specification] pointer how to do certain things, such as define
an eye opening spec, for example.
So we disagreed because we were talking about two different things.
Thanks, and sorry for the confusion.
Arpad
=====================================================================
_____
From: Walter Katz [mailto:wkatz@xxxxxxxxxx]
Sent: Friday, December 05, 2008 10:43 AM
To: Muranyi, Arpad; 'IBIS-ATM'
Subject: RE: [ibis-macro] Re: Making IBIS responsive to the modeling needs
of the industry ... new keyword [Specification]
Arpad,
I cannot disagree with you more. The external specifications I am pointing
to are Industry Standards (E.G. JEDEC, USB, and yes Hspice!).
When JEDEC specs DDR2 or DDR3, they are defining a set of measurement rules
that parts must comply with in order to have the JEDEC stamp of approval.
When a systems house designs a board using DDR2 or DDR3 components, and if
their simulations satisfy the JEDEC rules for DDR2/DDR3, then they can be
assured that their board will work with any qualified DDR2/DDR3 component.
So Having an IBIS part that has a model that is DDR2 or DDR3 qualified means
that that part will work as long as the simulation satisfy the JEDEC
DDR2/DDR3 rules.
What customers want are IBIS models that they can use in EDA tools that will
tell them if the simulations satisfy those JEDEC requirements. There is no
way of putting these JEDEC requirements into IBIS files today. Derating is
one example of a JEDEC rule, but there are others relating to AC, DC levels,
slew rates, how slew rates are measured, how long signals need to stay above
AC levels, . All I was saying is that IBIS needs to adapt these Industry
Standard Rules in a timely fashion either by aggressively adding measurement
parameters and keywords to IBIS, or by at least having a standard way of
pointing to Industry Standards.
IBIS has several functions, one as a pin list and assignment of models to
pins, one as an analog description of how drivers and receivers interact
with a channel, and one as a method of analyzing the signal at a receiver to
determine timing information. There are two philosophies of determining
timing information, one is to replicate the timing path inside an Rx as
accurately as possible, the second is to replicate the timing rules that
standards committees set on the requirements of chip manufactures to meet
timing steps for that standards committee's specifications.
You missed my entire point with your comment "your tool is still not going
to be able to use my eye opening description and my tool is not going to be
able to use yours.". What I said is that the [Specification] would point to
an Industry Standard Rule, not mine and not yours. I then said that each EDA
tool can implement this Industry Standard Rule in its own way. The external
file I described was just a way of describing the details of the Industry
Standard Rule. This file gets read by a human who decides on an
implementation of that rule for his EDA tool.
I think that you will find that many IBIS enhancement requests for new
keywords are simply desires to add the ability to specify industry standard
rules in IBIS.
Walter
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