Re: BIRD30 Prog. Buffers Comment

Hi Bob, Jon and Ibisans,

As you may recall from the BOF meeting at DAC this topic of
different strength, speed, you name it, I/O cells is a topic
that has been troublesome already to me in my short time applying
IBIS modeling to real world designs..

I think that the mechanism proposed in Bob's last posting works
if the simulator UI's can be coerced into it. I like this one:

Bob sezz..,

>Comments could provide a description of the buffers if they are no clear
>from the name. An alternative is to have another column required column
>for describing such buffers, similar to "signal_name in the [Pin] keyword:
>
>The description would not be standardized since there are many ways to
>differentiate models. The simulator could display the description and
>could optionally base a selection mechanism on the description. This
>syntax would then have two columns for each model for consistency.

If I understand this correctly the way to use this is as follows:
(I pirate freely from Bob's post)

[Component] PROGRAMMED_PART
[Manufacturer]
[Package]
| variable typ min max
R_pkg 0.0m NA NA
L_pkg 0.0nH NA NA
C_pkg 0.0pF NA NA
|
|***************************************************************
|
[Pin] signal_name model_name R_pin L_pin C_pin
1 OUT_1 Progbuffer2
2 OUT_2 Progbuffer1
3 OUT_3 Progbuffer2
4 OUT_4 Progbuffer1
|
|
[Model selector] Progbuffer1
| model name description
    ABCD0123456789ABCDE2 SS3.3 | the default
    ABCD0123456789ABCDE0 WS3.3
    ABCD0123456789ABCDE1 WF3.3
    ABCD0123456789ABCDE3 SF3.3
    ABCD0123456789ABCDE4 SF3.3_OD
|
[Model selector] Progbuffer2
| model name description
    ABCD0123456789ABCDE3 SF3.3 | the default
    ABCD0123456789ABCDE0 WS3.3
    ABCD0123456789ABCDE4 SF3.3_OD
    ABCD0123456789ABCDE5 SF5.0
    ABCD0123456789ABCDE6 SF5.0

Of course a list of the models in IBIS syntax would follow.
  
I would hope the simulator UI would bring up a list of the model names
available for the given pin, complete with the description, so that the
user would merely point and shoot at the desired model to be used for
that particular simulation.

I think the first one in the list after the [Model selector] should
automatically be the default. Saves making more keywords.

Am I in the ballpark on the usage model? I think this can work also for
a "whatif" mechanism for ASIC's and glue logic too! One of the problems
I have encountered is that currently if a [Model] isn't referenced by
a [Component] then it doesn't get loaded and so is not available for
"whatif" experiments(more than one vendor's sw exhibits this). This is
a neat way around that.

Thanks,

Brock Hannibal
HW Design Engineer
Tektronix, Inc.
Received on Wed Sep 6 15:06:30 1995