Re: [ng-spice-devel] personal note on ACS and NG-SPICE (fwd)


To ng-spice-devel@ieee.ing.uniroma1.it
From Paolo Nenzi <pnenzi@ieee.ing.uniroma1.it>
Date Sun, 17 Sep 2000 10:35:57 +0200 (CEST)
Delivered-To mailing list ng-spice-devel@ieee.ing.uniroma1.it
In-Reply-To <00091422521900.00990@spiff.al.dynip.com >
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Reply-To ng-spice-devel@ieee.ing.uniroma1.it



On Thu, 14 Sep 2000, Al Davis wrote:

> On Mon, 11 Sep 2000, Alan Gillespie wrote:
> > ...............How "credible"
> > as a re-vamped ACS versus a Spice rework ? I don't mean to be
> > cheeky, Al, it's just a matter of perceptions, i.e. Spice is an industry
> > standard, a benchmark.
> 
> Spice is an industry standard.  That can't be denied.  There are
> those who love it and will never change.  There are those always
> looking for change.  Spice has its problems, and I hear about them
> every day.  Some of this is from the industry leaders.


Al, I know (as the people on this list) that spice is not perfect. It it a
product 20 years old, and much has done in the VLSI design since it was
coded. I have read your messages, and not answer yet since Arno's and
Alan's replies were better than any I could write (they surely have
more experience than mine in computer circuit simulation). 

Something on C++: There was a discussion on C vs C++ in the early days of
spice development which ended with C as a winner. I am a C++ ignorant, the
only experience I have with C++ is an extension to an FLTK widget.
What about gnu C++ compiler, it is as fast as the C one (well, does the
C++ preprocessor works well) ? 

I think that software reuse is a good thing, and in the early days I have
looked on the net for packages that can be useful for a circuit simulator
package and found a lot of FORTRAN packages, a good number of them ported
to C and a very small number ported to C++. Is the situation changed ?


I agree with Arno, there exists a lot of languages and a lot glueing
routines, so we can even think to develop each part of the simulator in
the most convenient language. Arno showed me some code in guile which is
interesting.   


Al, I agree with you on the algorithmics of spice. Spice is a general
purpouse circuit simulator, it cannot be as fast as the latest developed
products, which consists of many modules sharing data structures every one
of them (modules) tailored to a specific problem. But it is general, it
can solve a lot of problems.  

Device models: Most of the public code is written for spice, but since
equations are provided, a model compiler (as in your plans) can help. We
need only a different backend for each simulator. Anyway, model compiler
is yet to come.


This message consist of a collections of "random" comments to the messages
on the ACS/ngspice topic. Al, I am pleased of your offer and, as
suggested by Arno, if you want some web space at no cost, I can give you
some space on the server where ngspice is hosted. I may have missed some
things, the messages were huge.

Regards,
Paolo


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