Re[2]: Clarifications on IBIS standard

Text item:

Fred,

Please post your questions and comments to this reflector. We have a good group
of people here who are more than willing to help. We are interested in
problems, observations or questions you have.

The 2.1 Spec does offer new data in the models, but retains 1.1 backward
compatibility. Backward compatibility is one of our guiding principles, to
avoid scaring people off with a spec that is evolving to better meet the needs
of the engineers using the models.

Regards,

Will Hobbs
Intel Corp.

Raj,

Items 3 through 5 are also of interest to me. I too have been wondering if
ibis@vhdl.org is the proper forum for those of us who are interested in the
application of IBIS data rather than the creation of IBIS data and standards.

It seems to me from the regular IBIS participation that there are mostly
representatives of IC and EDA tools vendors. I am sure that the tool
vendors will
eventually offer means of using IBIS data with their tools. In the
meantime, some
of the tool users (like me) must be struggling along trying to use
IBIS data as it
becomes available (and changes form).

I recently subscribed to the SI reflector, si-list@silab.Eng.Sun.COM
(subscribe to
si-admin@silab.eng.sun.com), but in the past two weeks, I've seen very little
discussion, an nothing relating to IBIS use.

If you want, I could let you know what I've been doing with IBIS data,
but maybe I
should take it off-line.

I would like to hear opionions regarding the proper forum for IBIS
use from all
you IBISians and SI-listians out there.

Fred
  fvance@FirePower.com
  FirePower Systems, Inc.
  190 Independence Dr.
  Menlo Park, CA 94025
  (415) 462-3055

Begin forwarded message:

Date: Thu, 2 Feb 95 10:30:08 PST
From: raghu@berlioz.nsc.com (Raj Raghuram)
To: ibis@vhdl.org
Subject: Clarifications on IBIS standard
Cc: chai@rockie.nsc.com

Clarifications on IBIS standard

We are in the process of making IBIS models and there were a few items
in the standard and in the discussions which were not clear to us. I hope
somebody can clear these issues.

1. When is the Golden Parser for version 2.0 likely to be ready ?

2. It is rightly pointed out that the pulldown and pullup
characteristic for tristate outputs may be non-monotonic. The standard
says that this can happen in at most one place. The i-v characteristic
may then locally have a negative resistance. Will this not pose a
problem to simulators ?

3. During a transition, it is not clear whether the pullup or pulldown
characteristics should be used by a simulator. This is not a problem
for making the IBIS models, but only for using them in a simulator.

4. Is there a provision for specifying a pad or die resistance i.e
R_comp in addition to C_comp?

5. The standard does not explicity specify the nature of the input
ramp in obtaining ramp rates. What should be the input rise time as
well as the high and low values of the input pulse?

Perhaps many of these issues have been thrashed out at different
forums. I would be greatly obliged if somebody would educate me on
this.

        Raj Raghuram
        National Semiconductor
        2900 Semiconductor Drive
        Mail Stop D3-677
        Santa Clara, CA-95052
        email: raghu@berlioz.nsc.com

        Phone: (408) 721-6220 (O)
        Phone: (408) 252-1285 (H)

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Subject: Re: Clarifications on IBIS standard
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