Re: Questions of Polarity and Enable

Hi,

If you are creating an IBIS model based on s2ibis utility, Polarity
and Enable are key in making the conversion work.

For Model_type Input, Polarity=1 sets the input for inverting while
Polarity=0 for non-inverting.

For Model_type I/O or 3-state, both Polarity and Enable fields are
expected. Enable specifies the pin number that enables the associated
output.

Regards,
Syed
National Semiconductor Corp.

>
>
> On Thu, 5 Dec 96 16:59:01 PST Zheng Shi of Symmetry wrote:
>
> >Hi, Ibis folks:
> >
> >Can anyone tell me what the sub-param Polarity and Enable of
> >keyword [Model] really means? Is Polarity used only on diff
> >pins? Is Enable used only on tri-state pins? How can I decide
> >the Polarity and Enable of an input or output pin?
> >
> >I can't find such detail information from IBIS2.1 Specification,
> >can anyone give me some advices, or tell me where i can find
> >the answer?
> >
> >Thanks a lot,
> >
> >-Zheng Shi
> > zheng@symmetry.com
> > Los Altos, CA.
>
> I belive the original intent was to support SSI logic components
> (74OO series TTL and the like) by allowing the user to include
> information on the outputs' logic operation. For example, the model provider
> could specify if the the path from input to output was inverting or
> non-inverting or if the enable on a tri-state output pin was high or
> low. However, for a lot of components (microprocessors, PALS/FPGAS, RAMS,
> etc.) these parameters don't seem to make much sense (to me, anyway). Unless
> you were modeling an SSI component where this made since, I would
> just default them to positive polarity and Active_high.
>
> Ibis old-timmers, any other comments?
>
> Best Regards,
> Stephen Peters
> Intel Corp.
>
>
Received on Fri Dec 6 15:20:28 1996