
                 PHILOSOPHICAL JUSTIFICATION OF GPL CVER

  We believe strongly that software should be distributed with source. 
  This allows users to study and understand Verilog algorithms as part
  of the circuit verification process. 

  However, since Pragmatic C is a commercial enterprise with salaries
  to pay, it does not make sense to release our software using only
  the open source model.  Namely, we are releasing an older version
  called GPL Cver under the GNU General Public License (GPL) and a new
  compiled version called CVC under a commercial license.  We have chosen to
  release the older GPL Cver version using the GNU GPL license because it 
  is currently the most popular free software license and because it allows the
  widest distribution. 

  We are not sure if the GNU development model will work with Ecad software
  tools such as Verilog simulators so we have not yet set up a formal system
  for user contributions.  One problem is that much of the current Cver
  behavior is the result of commercial users reporting mismatches with
  the de facto standard Cadence Verilog XL (TM) simulator.

  We think that the combination of GPL and compiled CVC
  is particularly good for Ecad software.  The GPL version allows 
  archiving the exact simulator source used for circuit sign off  
  along with design data so if there is a need for future changes, 
  the full set of design data (i.e. including the simulator used to process
  the data) can be retrieved to recreate the exact sign off conditions. 

  Since we are concerned about the high unemployment rate among programmers
  and design engineers, we want to encourage people to write their own
  commercial Ecad programs that communicate with Cver using the IEEE P1364
  Verilog HDL standard PLI API.  We believe that whoever wrote the PLI
  program should be able to select the type of license for software for
  which they hold the copyright.  Also, we believe that the GPL does not
  prohibit commercial programs (or any non GPL licensed programs for that
  matter) from being dynamically loaded and run by GPL Cver using the PLI API.
  We think the Linux operating system analogy applies.  Namely, it is
  acceptable to have Linux load executable programs (such as dynamically
  linked .so PLI programs) not licensed under GPL or LGPL.  We believe GPL
  Cver loading and execution of commercial programs is the same as Linux OS
  executing commercial programs that communicate through the standardized
  system call API.  However, we are not lawyers so you should consult a lawyer
  to help you decide how to license your PLI programs.

  We would like to hear your problems and suggestions (seen email to
  avanvick@pragmatic-c.com)

--
  TM - Verilog XL is a trademark of Cadence Design Systems, Inc.
  to GNU type group software development.
