Subject: New package model proposal by Steven Peters

From: Fred Vance <[email-masked]>
Date: Wed, 10 May 95 10:35:09 -0700

Hi,

I want to put in a word as an IBIS model user. First, I must admit that I haven't  
reviewed Steven's Egg carefully. I have only scanned it cursorily.

I don't believe that anyone would seriously propose providing IBIS models that are  
package dependent. Package information is desireable to the user. The more the  
better as long as it can be separated from the die information if necessary.

Am I wrong in thinking that some of the more complex packages like 200+ pin BGAs  
and PGAs are actualy circuit boards? If they are, then there are a lot of  
similarities with SIMMs.

If Steven's Egg will allow manufacturers to provide package information for SIMMs,  
I want to nominate him for IBISian of the year, even if that wasn't his intention.  
If the Egg won't allow for that level of package information, why not make it so  
that it will (provided the user can separate die and package information when  
necessary).

It may be difficult or impossible for anyone to convince SIMM manufacturers to  
provide SIMM package information, but I would like to leave the door open for them  
to do so.

I suspect that packaging information will become more and more important with time  
and that packaging will become more complex rather than less. Please keep the IBIS  
standard open to the future.

Regards,
Fred Vance
FirePower Systems, Inc.

Begin forwarded message:

To: [email-masked]
Subject: Re[2]: New package model proposal by Steven Peters
Date: Wed, 10 May 1995 09:26:09 -0700
From: Stephen Peters <[email-masked]>

Hello Chris, Kumar, Kellee and others:

  On 5/9 Chris Reed wrote:

>The problem as I see it is that the Egg proposes one way to model
>an MCM which may do for some particular part, but may be inadequate for
>some other part. We do not want to add to Ibis a plethora of syntaxes
>to support many different package model options.

     My proposal was never intended to model MCMs, SIMs, etc. and I belive
we should take a long, hard look before we start trying to describe
what amounts to complex circuit boards.  IBIS is a standard describing
*I/O buffers*; we are concerned about the packaging only is as much as
its effects are inseperable from the actual silicon characteristics.
Also, this proposal is an attempt to refine what has already been defined,
not come up with a whole new scheme.  It does cover existing DIP/SOIC/
PQFP/BGA/PGA/TAB packages -- basicly any package where the leadframe
can be represented as multipule elements in series, with coupling between
any set of arbitary elements.
    This may be a bit of a philosophical discussion, but consider this:
users, given half a chance, would take a '.pkg' file that allows general
descriptions and use it to describe an entire motherboards net topology. 

This may be a 'great and wonderful' thing, but is that the intent of IBIS?

         Regards,
         Stephen Peters

---

From: Arpad Muranyi <[email-masked]>
Date: Wed, 10 May 95 13:09:00 PDT

Text item: 

Fred,

Do I understand you correctly?  Are you suggesting that the PCB portion of SIMMs
should be described as if they were packages?

Even though I see the similarities between PCBs and MCMs or other types of 
packages, I strongly disagree with your wish to be able to handle SIMMs as if 
they were packages.  SIMMs are clearly printed circuit boards with multiple 
components on them and they should be handled as such.  The best way of doing so
is to make full-board simulation tools understand multiple board situations, so 
that a motherboard with a SIMM (or more) could be simulated as two or more PCBs 
connected together.

As Stephen said, IBIS is a component modeling format and not a PCB description 
language.

The question in my mind is whether MCMs and the like should be handled as PCBs, 
because from a user's point of view, an MCM package is one piece of something 
and from the outside it looks like a single component.

It is true, that vendors have a hard time to release models of their SIMMs.  If 
you were a SIMM vendor, which format would use to create a model?  Quad, xSPICE,
Interconnectix, EDIF, etc...?

As I see it, a generic interconnect description language standard is missing 
here, which could be used by any simulation tool.  This standard should have the
capabilities to describe PCBs as well as packages, and then it could be used for
SIMMs, motherboards, MCMs, complex packages, etc...

Arpad Muranyi
Intel Corporation,
Folsom, CA
-------------------------------------------------------------------------------
Hi,
...
Am I wrong in thinking that some of the more complex packages like 200+ pin BGAs
and PGAs are actualy circuit boards? If they are, then there are a lot of 
similarities with SIMMs.

If Steven's Egg will allow manufacturers to provide package information
for SIMMs, I want to nominate him for IBISian of the year, even if that wasn't
his intention.  If the Egg won't allow for that level of package information, 
why not make it so that it will (provided the user can separate die and package 
information when necessary).
...
Regards,
Fred Vance
FirePower Systems, Inc.

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Subject: New package model proposal by Steven Peters
To: [email-masked]
Date: Wed, 10 May 95 10:35:09 -0700
From: Fred Vance <[email-masked]>
:37:12 -0700
Received: from hermes.intel.com by relay.jf.intel.com with smtp
     (Smail3.1.28.1 #2) id m0s9GM8-000twYC; Wed, 10 May 95 11:19 PDT

---

From: [email-masked] (Richard Shi)
Date: Wed, 10 May 1995 14:13:25 -0700 (PDT)

> Interconnectix, EDIF, etc...?

Any interest in using VHDL-A, Analog VHDL, currently being defined 
by IEEE 1076.1?

  Best regards,

  Richard Shi
  [email-masked]

---

From: Fred Vance <[email-masked]>
Date: Wed, 10 May 95 14:43:43 -0700

Arpad,

Yes you understand me correctly. How else am I going to model a DRAM SIMM connected  
to and loading my main logic board? Without having the vendor's PCB design  
database, I have to guess how long each control, address, or data line is and what  
the impedance and delay characteristics are, and I have to assume that there is no  
coupling between traces. 

If the SIMM were treated as a package it would be possible to define the minimum  
and maximum delay and loading for each signal. This would allow the vendor to  
provide information about his SIMM without revealing his PCB design. From my point  
of view, a 72 pin SIMM is no different than a 100 pin PGA. Unless I want to dissect  
the package, I only know what the vendor tells me.

If I were a SIMM vendor, I would use IBIS to describe my SIMMs if possible. If IBIS  
allows bond wires and lead frames to be described and if Steven Peters' Egg will  
enable IBIS to add coupled or uncoupled transmission lines to the package  
description or some equivalent matrix, it seems to me that it would be possible for  
a SIMM vendor to provide the information that I need without revealing his PCB  
design.

Where do we draw the line between components and circuit boards? My car has an air  
flow sensor circuit board with two die on it. I have read in news reports, that the  
P6 has two die in one package. I believe the difference lies only in the need for a  
person to successfully design the part into an application. If the success of the  
design depends on knowning the I/O buffer and package characteristics, to me at  
least, it is a component.

Regards,
Fred Vance

Begin forwarded message:

Date: Wed, 10 May 95 13:09:00 PDT
From: Arpad Muranyi <[email-masked]>
To: [email-masked], [email-masked]
Subject: Re: New package model proposal by Steven Peters

Fred,

Even though I see the similarities between PCBs and MCMs or other types ofpackages,  
I strongly disagree with your wish to be able to handle SIMMs as ifthey were  
packages.  SIMMs are clearly printed circuit boards with multiplecomponents on them  
and they should be handled as such.  The best way of doing so
is to make full-board simulation tools understand multiple board situations, sothat  
a motherboard with a SIMM (or more) could be simulated as two or more PCBsconnected  
together.

As Stephen said, IBIS is a component modeling format and not a PCB  
descriptionlanguage.

The question in my mind is whether MCMs and the like should be handled as  
PCBs,because from a user's point of view, an MCM package is one piece of  
somethingand from the outside it looks like a single component.

It is true, that vendors have a hard time to release models of their SIMMs.  Ifyou  
were a SIMM vendor, which format would use to create a model?  Quad, xSPICE,
Interconnectix, EDIF, etc...?

As I see it, a generic interconnect description language standard is missinghere,  
which could be used by any simulation tool.  This standard should have the
capabilities to describe PCBs as well as packages, and then it could be used for
SIMMs, motherboards, MCMs, complex packages, etc...

Arpad Muranyi
Intel Corporation,
Folsom, CA