Subject: IBIS 3.0 model

From: Joseph Brcich <[email-masked]>
Date: Mon, 07 Dec 1998 11:15:36 -0800

I am in the process of creating an IBIS 3.0 for our K6-2 processor.

When using ibischk3 It Gives me the following errors:
Pull down has decreasing current.
Gnd clamp has decreasing current.

Can anyone tell me what these mean? What charateristic of the data
should I look at? Is there a document that describes the error messages?
Most are self explanatory but this one stumped me.

Also is there a working IBIS 3.x model that I can use as an example?

Thanks in advance
Joe Brcich
Advanced Micro Devices

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From: "D. C. Sessions" <[email-masked]>
Date: Thu, 10 Dec 1998 12:19:59 -0700

> Gnd clamp has decreasing current.

First off, these are warnings, not errors.

There are a lot of reasons why an I/V curve might be nonmonotonic,
ranging from numerical artifacts to inconsistent test conditions
to real nonmonotonicity due to feedback.  Many processors have weak
bus keepers on their I/O lines to prevent float, and that would do
the trick.

> Most are self explanatory but this one stumped me.

What I'd do is copy & paste the I/V curves into a spreadsheet and
generate the sum and its differences.  That should show the effect
up pretty neatly and let you apply the grey colloidial debugger.

-- 
D. C. Sessions
[email-masked]