ngspice/FAQ

  Ngspice F.A.Q.Version 1.2
  Maintained by Paolo Nenzi <p.nenzi@ieee.org>
  Last update: 02-11-2003

  This document contains the Frequently Asked Questions (and Answers)
  for ngspice project.
  __________________________________________________________________________

  Table of Contents


  1. INTRODUCTION AND GENERAL INFORMATION
     1.1 What is ngspice?
     1.2 Why resurrecting Berkeley's Spice?
     1.3 What is the project's goal?
     1.4 What you are going to do?
     1.5 Legal issues
     1.6 What mailing lists exist for ngspice?
     1.7 Are the mailing lists archived anywhere?
     1.8 What newsgroups exist for ngspice?
     1.9 Where can I get a copy of ngspice?
     1.10 Where should I look on the World Wide Web for ngspice stuff?
     1.11 Where should I look on the World Wide Web for Spice documentation?

  2. DEVELOPMENT
     2.1 What is the current version?
     2.2 What are the latest features in the current release?
     2.3 What does it look like?
     2.4 Who are the authors of ngspice?
     2.5 How can I report a bug/request for a feature?
     2.6 How can I join the development?

  3. SOLUTIONS TO COMMON MISCELLANEOUS PROBLEMS
     3.1 What systems are supported?
     3.2 I get errors when I try to compile the source code, why?
     3.3 This document didn't answer my question. Where else can I look for
         an answer?

  4. ADMINISTRATIVE INFORMATION AND ACKNOWLEDGEMENTS
     4.1 Feedback
     4.2 Formats in which this FAQ is available
     4.3 Authorship and acknowledgements
     4.4 Disclaimer and Copyright


  ______________________________________________________________________

  1.  INTRODUCTION AND GENERAL INFORMATION



 1.1 What is ngspice ?

  Ngspice is the name of a project and of a program in the project.
  The idea behind the project is to improve the capabilities of the
  Spice 3f5 circuit simulator. Spice is the most famous circuit 
  simulator, developed at the University of California at Berkeley 
  (UCB), by "a cast of thousand". The NG prefix has a lot of meanings: 
  Next Generation, New Good, etc. Choose or invent the one you prefer. 
  The heart of the project is the ngspice program, a circuit simulator 
  derived from spice3f5.


 1.2 Why resurrecting Berkeley's Spice?
  
  Berkeley's Spice can be considered the father of most circuit
  simulators available today. It is an old but still good piece of
  software, it may not be the fastest or the most reliable but it's
  free, it's available in source code and most of the electrical
  simulators inherited it's syntax. On the more technical side, spice3
  uses good numerical algorithms (most commercial implementations have
  only strengthened them), implements most of the models for MOSFET
  submicron designs and has a powerful set of analyses. On the more
  "social" side, spice3 it's well introduced in the academic
  environment.

 
 1.3 What is the project's goal?

  The project goal evolved during project development, at first the
  final goal was to develop a reliable, fast and friendly circuit 
  simulator for mixed signal/mixed level simulation. During 
  development it become apparent that to reach the goal a complete
  rewrite of spice was needed. Since it was almost absurd to rewrite
  Spice and since a new simulator was already under development:
  ACS (Al's Circuit Simulator), now GNUCap (GNU Circuit Analyis
  package), the goal of nspice became less utopical: merge
  spice, xspice and cider into a mixed-signal/mixed-level simulator
  that can be used as a reliable engine. 


1.4 What you are going to do?  

  We are going to develop a mixed-signal/mixed-level circuit simulation
  program integrating three different spice based simulators:
  Spice, Xspice and Cider.
  
  Xspice is a mixed-signal circuit simulator developed by GTRI (Georgia 
  Tech Research Institute) at Georgia Institute of Technology. Xspice
  was originally developed as an extension over Spice3c1. Xspice
  introduces code modeling and a digital simulator into ngspice.
  The "home site" of Xspice is: 
  
           http://users.ece.gatech.edu/~mrichard/Xspice/
  
  Cider is a mixed-level circuit and device simulator based on Spice3f5
  that couples a device simulator (DSIM) to Spice. More information can
  be found at:
  
        http://www-cad.eecs.berkeley.edu/Software/cider.html 
  
  The merging process is done in parallel with bug fixing and improvement
  of the three simulators. The improvements are concentrated into 6
  directives:
  
  
  + Compact models:  the improvements in compact models will address
    mainly the implementation of additional effects not available
    in the original code. Device specific improvements are documented
    on ngspice's documentation and in the DEVICE file in project's
    tarball.
    Improvements that affects all devices already implemented are:
    "dtemp" option to set instance's temperature relative to the circuit 
    one, "m" parallel multiplier to simulate an arbitrary number of
    instances of the same kind connected in parallel.
    
    Planned improvements are the development of a dynamic loading
    mechanism for compact models, to avoid loading in memory devices
    that are not needed, and SOAR (Safe Operating ARea) checks to 
    identify situations in which devices are used out of their
    safety areas.  
  
  
  + Simulator's analyses: this is a low priority area. Planned improvements
    include the implementation of parametric analyses, to analyse the
    behavior of the circuit as a parameter changes. Parameter sweep,
    Monte Carlo and Worst Case fall in this category. Network analysis
    (double bipole parameters extraction) is another planned improvement.       
    
  
  + Numerical analysis code: the improvements within the numerical code
    must be done with extreme care. Planned improvements are, the 
    replacement of the Sparse library with the latest code Kenneth Kundert
    has released, available at:

               http://sourceforge.net/projects/sparse
   
   Other planned improvements, but with very low priority, includes the
   use SuperLU library as possible Sparse library replacement (the 
   library is available at http://crd.lbl.gov/~xiaoye/SuperLU) and the
   introduction of continuation metohds to aid DC convergence. 
  
  
  + Spice language: The language used to input the circuit to the simulator
    has been extended and now allows the user to input parametric values
    for components (the numparam library). This is an experimental feature 
    that will be improved in the future. Planned improvements includes the
    support for loading more than one circuit, netlist manipulation via
    command line (adding and removing instances) and the implementation
    of a command history using the libedit library, available at:
     
                 http://sourceforge.net/projects/libedit
    
  
  + Frontend: The design of a new spice frontend has not been successful
    and now is orphaned, since the is no interests and many free and
    commercial frontends are available. There is no planned improvement
    here.
    
  
  + Documentation: Commercial simulators have very good manuals with
    tutorials, models equations explained, example of use, suggestions,
    etc. Spice came with little documentation. The Spice3f manual, 
    available on the Internet will be constantly improved during
    ngspice development and integrated with the documentation 
    accompanying Xspice and Cider. This is a very time consuming task
    and probably the documentation will always be left slightly 
    behind.
   


  1.5 Legal issues

  Ngspice merges three different simulators: spice and cider are covered
  with the "old" BSD license, Xspice by its own license. The ngspice 
  license will be then the BSD license. 
  
  Since the "old" BSD license is not compatible with the GPL library
  it is not possible to link the ngspice with GPL'ed code, as is
  written in:
  
             http://www.gnu.org/philosophy/bsd.html
   
  The group developing ngspice has written to Berkeley's copyright holders
  asking to change the license to the new BSD, which has the 
  incompatibility removed, but without success. Ngspice will probably
  never be relased under the GPL license.
  
  


  11..66..  WWhhaatt mmaaiilliinngg lliissttss eexxiisstt ffoorr nnggssppiiccee??

  There are three mailing lists dedicated to the ngspice project. Send
  an empty message to the following addresses to get information on
  subscription.  <ngspice-users-help@lists.sourceforge.net>

  <ngspice-devel-help@lists.sourceforge.net>


  <ngspice-frontends-help@lists.sourceforge.net>



  11..77..  AArree tthhee mmaaiilliinngg lliissttss aarrcchhiivveedd aannyywwhheerree??

  Yes, the list are archived. Look at the project's web site to access
  archives.


  11..88..  WWhhaatt nneewwssggrroouuppss eexxiisstt ffoorr nnggssppiiccee??

  None. Sorry.


  11..99..  WWhheerree ccaann II ggeett aa ccooppyy ooff nnggssppiiccee??

  You can download ngspice from:

  <http://sourceforge.net/projects/ngspice>


  11..1100..  WWhheerree sshhoouulldd II llooookk oonn tthhee WWoorrlldd WWiiddee WWeebb ffoorr nnggssppiiccee ssttuuffff??

  Look at the official NG-Spice Web Page
  <http://ngspice.sourceforge.net>


  11..1111..  WWhheerree sshhoouulldd II llooookk oonn tthhee WWoorrlldd WWiiddee WWeebb ffoorr SSppiiccee ddooccuummeennttaa--
  ttiioonn??

  50 Circuits analyzed with SPICE
  <http://www.dacafe.com/DACafe/EDATools/EDAbooks/SpiceHandBook/01_TOC.html>

  <http://www.dacafe.com/DACafe/EDATools/EDAbooks/SMPS/SMPS.htm>


  22..  DDEEVVEELLOOPPMMEENNTT



  22..11..  WWhhaatt iiss tthhee ccuurrrreenntt vveerrssiioonn??

  rework-14 (released on 10/12/2001)


  22..22..  WWhhaatt aarree tthhee llaatteesstt ffeeaattuurreess iinn tthhee ccuurrrreenntt rreelleeaassee??

  New features:

  +o  New functions for vectors: vecmax (find max element in a vector),
     vecmin (find minimum element in a vector), vecd (differentiate a
     vector).

  +o  BSIM 4 and support EKV models.

  Bug fixes:

  +o  Some memory leaks closed.

  +o  Error reporting more verbose



  22..33..  WWhhaatt ddooeess iitt llooookk lliikkee??

  This is a command line utility, no screenshots!


  22..44..  WWhhoo aarree tthhee aauutthhoorrss ooff nnggssppiiccee??

  The development is open to anyone who wish to contribute.

  People who contributed are (in alphabetical order):

  +o  Daniele Foci <dfoci@ieee.ing.uniroma1.it>

  +o  Paolo Nenzi <pnenzi@ieee.ing.uniroma1.it>

  +o  Arno Peters <A.W.Peters@ieee.org>

  +o  Serban-Mihai Popescu <serbanp@ix.netcom.com>

  +o  Emmanuel Rouat <emmanuel.rouat@wanadoo.fr>

  +o  Michael Widlok <twidlok@uci.agh.edu.pl>


  This list is surely incomplete (due to open development group), there
  are many people who contributed with improvements, pieces of code, bug
  fixes, etc. If you have contributed and do not appear, write to:

  <ng-spice@ieee.ing.uniroma1.it>

  and ask to be included.


  22..55..  HHooww ccaann II rreeppoorrtt aa bbuugg//rreeqquueesstt ffoorr aa ffeeaattuurree??

  Look at the projects summary page: ngspice summary page

  22..66..  HHooww ccaann II jjooiinn tthhee ddeevveellooppmmeenntt??

  To join the development just code the feature you want to add and send
  your patch in the mailing list.  Before you start coding check the
  latest development release of ngspice from our CVS. It might be that
  your feature has already been implemented.


  33..  SSOOLLUUTTIIOONNSS TTOO CCOOMMMMOONN MMIISSCCEELLLLAANNEEOOUUSS PPRROOBBLLEEMMSS



  33..11..  WWhhaatt ssyysstteemmss aarree ssuuppppoorrtteedd??

  This is the updated list:

  Hardware           O.S. Version            Compiler       Functional?
  ----------------   ----------------------- -------------- -----------
  ????               HP-UX 10.10             gcc 2.95.2     yes
  IBM Risc 6000      ???                     lcc            no
  i386               Debian GNU/Linux 2.1    gcc 2.7.2      yes
  i386               Red Hat Linux 5.2       gcc 2.7.2      yes
  i386               SuSE Linux 6.0          gcc 2.7.2      yes
  i386               Linux (SuSE)            gcc            yes
  UltraSPARC         Solaris 7               gcc            yes
  UltraSPARC         Solaris 7               SUN Workshop   ?



  MS-Dos, VMS and MacOS are no longer supported.


  33..22..  II ggeett eerrrroorrss wwhheenn II ttrryy ttoo ccoommppiillee tthhee ssoouurrccee ccooddee,, wwhhyy??

  [not written yet]


  33..33..  TThhiiss ddooccuummeenntt ddiiddnn''tt aannsswweerr mmyy qquueessttiioonn.. WWhheerree eellssee ccaann II llooookk
  ffoorr aann aannsswweerr??

  Read old messages from the mailing list archive, search the web site
  or read the docs.  Upgrade to the latest version of ngspice, many
  problems are fixed in the new versions.  If you still can't find an
  answer, post your question to the mailing list.


  44..  AADDMMIINNIISSTTRRAATTIIVVEE IINNFFOORRMMAATTIIOONN AANNDD AACCKKNNOOWWLLEEDDGGEEMMEENNTTSS


  44..11..  FFeeeeddbbaacckk

  Send your comments about this F.A.Q. to:

  Paolo Nenzi <p.nenzi@ieee.org>.

  Send your comments about ngspice to:

  Paolo Nenzi <p.nenzi@ieee.org>.


  44..22..  FFoorrmmaattss iinn wwhhiicchh tthhiiss FFAAQQ iiss aavvaaiillaabbllee

  This document is available only in ASCII format in the ngspice source
  package.


  44..33..  AAuutthhoorrsshhiipp aanndd aacckknnoowwlleeddggeemmeennttss

  Parts of the questions and answers are originate from Paolo Nenzi.


  44..44..  DDiissccllaaiimmeerr aanndd CCooppyyrriigghhtt

  This document is provided as is. The information in it is not
  warranted to be correct: you use it at your own risk.