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.