Re: bird 37.1

I see two issues with bird 37.1 that I think we should conciously
address. Not to say that we shouldn't pass this bird, but we should only
pass it if we are willing to live with these limitations:

1) This only describes point to point connections. It cannot be used for
SIMMS or connectors that use multiple connections. It cannot be used for
any package that might (for instance) route two ground pads to the same
pin).

2) It can only be used to describe packages that are single layer. While
it could describe some multi-layer packages I can give a few quick
counter examples of easy to imagine scenarios that can only occur (and
probably would occur) with 2 level packageing. Here is one:

(these lines don't touch but the verticle lines do couple)

______________
             _|___________
            | |
            | |___________
____________|

If you think that you can represent this then think about the following
and how it would be Different: (once again, only the verticle lines
coupled)

__________________
________________ |
                | |
                | |
                | |___________
                |_____________

I think that the bird37.1 description of these two examples would be the
same circuit even though they are clearly electrically different.

The question of whether we want to "go ahead" and do this even though it
has some basic limitations is I think what we need to decide.

regards,
jon
Received on Thu Sep 5 16:32:35 1996