Subject: RE: BIRD 9.1 -- package connections

From: Stephen Peters <[email-masked]>
Date: Mon, 14 Mar 1994 17:40:15 -0800

Hello Bob, and Fellow IBISans --

     Regarding BIRD 9.1, how do we specify what pins in a resistor package
     are the 'common' or associated pins?  I'm thinking that when a
     simulator goes to parse a resistor model and put it into the target
     netlist the simulator needs to know the pins on the package relate to
     the resistors.  Let me illustrate.

    Suppose we have a collection of pullup resistors in a 10 pin SIP as
    follows:

         1
         |
         |
         |------------------------
         |  |  |  |  |  |  |  |  |
         R  R  R  R  R  R  R  R  R
         R  R  R  R  R  R  R  R  R
         R  R  R  R  R  R  R  R  R
         |  |  |  |  |  |  |  |  |
         |  |  |  |  |  |  |  |  |
         2  3  4  5  6  7  8  9  10

     How is one supposed to designate that pin 1 is the common pin?  Would
     doing something like this work?
     
     [Pin]   signal_name    model_name
       1      common          POWER
       2        R1	      res1
       3        R2            res1
       .         .            .
       .         .            .

     The same question applies to a thevinen type resistor package.  Does
     listing the two common pins as POWER and GND accomplish what we need?

     There is also a third case: straight thru resistor in a DIP or SIP
     pack.

            ____________
            |          |
      1-----|---RRRR---|----14
      2-----|---RRRR---|----13
      3-----|---RRRR---|----12
                 .
                 .
                 .
      
      7-----|---RRRR---|----8
            |__________|

      How is the model going to tell the simulator that pin 7 is associated
      with pin 8, for example?  To me it seems that, based on a keyword or 
      model type, both the IBIS model and simulator have to assume some
      kind of topology for the resistor connections.  What do you think?

     Best Regards,
     Stephen Peters
     Intel Corp.