Yet Another Comment ( Sorry, I can't get another "C" in here )

All -

I actually agree that the question of mutuals is othogonal to the pin mapping
that this BIRD deals with. It occurred to me at the time of writing so I
mentioned it. I have no problem at all with saving it for another BIRD, and
had thought about adding it to one I am trying to work out to generalize the
mapping for more complex cases such as I presented earlier. Still the
suggested EGG ( I like that ! ) has a lot of merit. I also like the idea of
the separate [PackageModel] keyword. It occurs to me that some kind of file
include mechanism, such as the (in)famous #include in C or ~r in many e-mail
programs which takes a path name as argument and merges the contents of it in
line in the text would be useful in this context. It should fit into the
established keyword syntax, however, such as maybe [Include], [Library],
[Merge], or [Read] or some such variation. Path names can easily exceed the
80 character limit, though, and I do support that limit as a matter of
practical convenience, even though not dogmatically. Thus we may have some
extra baggage here such as a [path] keyword, use of the path environment
variable on UNIX(tm) and DOS systems, or even add an environment variable
such as ibispath.

I am still thinking about how to best represent mutuals. Much can be said
for the matrix approach, as well as the text based approach in the EGG, and I
have yet to convince myself of a compelling reason to come down on one side
or the other. One caveat though: beware of arbitrarily deciding that some
mutuals can be eliminated due to their small magnitude. Jacob White of the
Research Laboratory of Electronics at MIT has some interesting examples of
packaging where, due to the nature of the internal circuitry, a number of
"far away", and thus small magnitude, mutuals "ganged up" on another signal
pin and ruined the waveform there during certain transitions. So there needs
to be a basis for discard of mutuals, probably based on knowledge of some
constraints on simultaneous switching patterns.

Anyway this sounds like just the level of discussion I had wanted to start
about mutuals, etc. Sounds like a number of good ideas coming forth, and
that is the stuff that will move ibis forward.

Thanks,

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    / \ / / Bob Ward
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Received on Thu Dec 16 06:56:29 1993