  Ngspice F.A.Q.Version 1.7 (rework-22 release)
  Maintained by Paolo Nenzi, Holger Vogt
  Last update: 25-09-2010

  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 What is tclspice ?
     1.3 Why resurrecting Berkeley's Spice?
     1.4 What is the project's goal?
     1.5 What you are going to do?
     1.6 Legal issues
     1.7 What mailing lists exist for ngspice?
     1.8 Are the mailing lists archived anywhere?
     1.9 What newsgroups exist for ngspice?
     1.10 Where can I get a copy of ngspice?
     1.11 Where should I look on the World Wide Web for ngspice stuff?
     1.12 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 a mixed-level/mixed-signal circuit simulator based on three 
  open source software packages: Spice3f5, Cider1b1 and Xspice: 
  
  - Spice3 is a widely used circuit simulator. It was developed by the 
    University of California at Berkeley (UCB), by "a cast of thousand" 
    (as they say) initially under the guide of Donald O. Peterson.
  
  - Cider is a mixed-level simulator that already includes Spice3f5 and 
    adds a device simulator to it: DSIM. Cider couples the circuit level 
    simulator to the device simulator to provide greater simulation 
    accuracy (at the expense of greater simulation time). Critical 
    devices can be described with technology parameters (numerical 
    models) and non critical ones with the original spice's compact 
    models.

  - Xspice is an extension to Spice3 that provides code modeling support 
    and simulation of digital components through an embedded event 
    driven algorithm.

  The NG prefix has lot of meanings: Next Generation, New Good, etc. 
  Choose or invent the one you prefer. The heart of the project is the 
  ngspice program.


 1.2 What is tclspice ?

  Tclspice is a circuit simulator that embeds ngspice and provides a 
  tcl/tk interface to the user. Tclspice is both a batch and interactive
  simulator and a building block for simulator applications. Analyses can 
  be run from a tcl script and vector plotted or post processed using tcl
  or a small GUI can be built to analyze a circuit or a set of circuits.
  Tclspice is obtained compiling ngspice activating an additional option.

  
 1.3 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. Spice3 is based on proven numerical 
  algorithms (most commercial implementations have only strengthened 
  them), implements most of the models for MOSFET submicron design 
  and has a powerful set of analyses. The readily availability of
  its source code in the past made this simulator the de-facto standard.

 
 1.4 What is the project's goal?

  Ngspice is both a maintenance and enhancement project. It is a maintenance
  project because it aims to provide the free EDA community the best spice3
  simulator available. This means fixing bugs, adding new features but always
  in the spice3 framework. Achieving compatibility with commercial spice based 
  simulators and provide users the latest devices models are important goals
  of the project. Improvements in the postprocessing (data handling 
  capabilities) and user interface are other goals.  


 1.5 What you are going to do?  

  An official roadmap for ngspice was never drawn. Contributions made by
  developers drive ngspice development and the roadmap is built day by 
  day by developers writing on the lists. Ngspice development activity
  can be summarized in 3 points:

  + Compatibility: Ngspice should be compatible with commercial products,
    thus allowing people to use the netlist generated for such tools. As 
    most of the commercial simulators avaiable tracked each other in netlist
    language, this should not be an impossible task. The most important goal
    here is to provide a reliable support for model libraries coming from
    foundries.  
  
  + Compact models:  The interest in using ngspice is intimately connected
    to the available models. To provide the latest models available for 
    active and passive devices is a fundamental goal of the project. In
    this direction we are integrating ADMS model compiler into ngspice.

  + Documentation: Commercial simulators come with very good manuals 
    containing tutorials, description of models equations, example of 
    use, suggestions, etc. Spice came with little documentation. The 
    Spice3f manual, available on the Internet has been used as the basis
    for the new manual. It 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.
   

 1.6 Legal issues

  Ngspice, starting from release rework-18 is released under BSD/LGPL 
  license. Part of the code are covered by other compatible licenses:
  spice3 and cider are BSD, xspice is Public Domain and TCLSPICE is 
  LGPL and the copyright is of their respective owners (need to write better)


 1.7.  What mailing lists exist for ngspice?

  There are two general mailing lists dedicated to the ngspice project. 
  
  Users mailing list: <ngspice-users@lists.sourceforge.net>
  This list is for ngspice users, examples, problems, bug reports
  and general discussion on ngspice can be sent here. 
  
  Developers mailing list: <ngspice-devel@lists.sourceforge.net>
  The list dedicated to ngspice development. Developers shold 
  subscribe here, to follow the program development. May be used
  to send patches, and technical discussion on ngspice. 
  
  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>


 1.8.  Are the mailing lists archived anywhere ?

  Yes, the lists are archived. There are two places where to look for
  archives. The project started on the IEEE Central and South Italy
  web server and then moved to sourceforge. Sourceforge provides an
  archiving service that cam be accessed via the summary page:
  
                     http://sourceforge.net/projects/ngspice
  
  (look for the "Lists" link). Old messages from the pre-sourceforge 
  age are available at:
  
                    http://ngspice.sourceforge.net/lists.html    


 1.9.  What newsgroups exist for ngspice?

  There is no ngspice specific newsgroup. Anyway ngspice threads appear
  on newsgroups dedicated to circuit simulation and electronic design.
  An (incomplete) list is:
  
  sci.electronics.cad
  comp.lsi.cad 


 1.10.  Where can I get a copy of ngspice?

  You can download ngspice from:

                      http://sourceforge.net/projects/ngspice


 1.11.  Where should I look on the World Wide Web for ngspice stuff?

  Look at the official Ngpice Web Page:
  
                           http://ngspice.sourceforge.net


 1.12.  Where should I look on the World Wide Web for Spice documenta-
        tion?

  There is a detailed ngspice manual available at:
  http://ngspice.sourceforge.net/docs.html
 
  There are a lot of Internet sites that have information on spice. The
  best way is to ask your preferred search engine. Some interesting
  sites are: 
 
  Pages on Spice:
   http://bwrc.eecs.berkeley.edu/Classes/IcBook/SPICE/
   http://embedded.eecs.berkeley.edu/pubs/downloads/spice/index.htm
   http://newton.ex.ac.uk/teaching/CDHW/Electronics2/userguide/index.html#toc
  
  Xspice Page:
   http://users.ece.gatech.edu/~mrichard/Xspice

  Cider Page:
   http://embedded.eecs.berkeley.edu/pubs/downloads/cider/index.htm



  2.  DEVELOPMENT


 2.1.  What is the current version?

  The latest version released is: 
  
  * ngspice-rework-22 (released on 26/09/2010)
  

 2.2.  What are the latest features in the current release?

  New features:
    + OpenMP multicore support for BSIM3, BSIM4, and BSIMSOI4
    + reinstate {$var} expansion in interactive interpreter
    + .TITLE line added
    + update to 'spectrum' script
    + par('expression') in .four, .plot, .print, .meas, .save commands
    + command 'option' for use in spinit, .spiceinit, and in scripts
    + adms procedure updated
    + new random number generator, random functions sunif() and sgauss()
    + ngspice manual updated 

  Bug fixes:
    + Major code cleanup to reduce compiler/linker warnings: ansi function prototypes, 
      void/char pointers to named pointers, explicit type casts and many more  
    + Many small bugs



 2.3.  What does it look like?

  Ngspice, as the original Spice3 (and Xspice and Cider) is a command
  line simulator.


 2.4.  Who are the authors of ngspice?

  The development is open to anyone who wish to contribute. If the 
  original Spice3 was made with the contribution of "a cast of 
  thousand", ngspice can only increase that number. An incomplete
  list of contributor makes the "acknowledgements" page of the ngspice
  manual.  


 2.5.  How can I report a bug/request for a feature?

  The ngspice summary page (hosted on Sourceforge) has bug-reporting,
  feature-request and bugs trackers. You can use them or subscribe to
  mailing lists and post there. The former is preferred since almost
  it allows to track all necessary actions upon a bug. The web site at
  http://ngspice.sourceforge.net/bugrep.html will give you more details.

 
 2.6.  How can I join the development?

  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.
  
  There is no bureaucracy here.



  3.  SOLUTIONS TO COMMON MISCELLANEOUS PROBLEMS


 3.1.  What systems are supported?

  Ngspice is written in C, and uses some GNU extensions, then you need
  a GNU C compiler and a UNIX environment to compile it. Ngspice can
  be compiled under Windows using  the mingw or cygwin environment as
  well as MS Visual Studio.
  

 3.2.  I get errors when I try to compile the source code, why?
  
  This is a one-million-euros question :). 
  
  Write a mail to the user's list describing the problem and providing
  information on the type of hardware, the flavour of operating system.


 3.3.  This document didn't answer my question. Where else can I look
        for an answer?
	
  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 lists.



  4.  ADMINISTRATIVE INFORMATION AND ACKNOWLEDGEMENTS


 4.1.  Feedback

  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>.


 4.2.  Formats in which this FAQ is available

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


 4.3.  Authorship and acknowledgements

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


 4.4.  Disclaimer and Copyright

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