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What is Open about Si2 OpenAccess?

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By Marshall Tiner
Director of Production Standards
Si2

What is open about Si2 OpenAccess?

It seems these days everything is “open,” and the terms get confusing. Here is a short history of a few key areas to help clarify things. The label “open source” is credited to the free software movement of 1998. In February of that year, the Open Source Initiative (OSI) was founded and the Open Source Definition adopted. OSI tried to trademark the term “open source,” in an effort to control its usage.

So, what does open source mean?

The term refers to a licensing methodology whereby the source code is made publicly available. Depending on the license terms, others may then download, modify, and publish their version (fork) back to the community. The Apache Software Foundation’s license has become a standard within the open source world.

Silicon Integration Initiative (Si2) was born out of the 1988 CAD Framework Initiative (CFI), with a goal of enabling design tool interoperability. Cadence developed the OpenAccess API to standardize the design database, which resulted in just such a means of interoperability. With the contribution of the OpenAccess API, the OpenAccess Coalition was formed within Si2. To the design tool user this meant a huge productivity increase when using tools from different suppliers.

Before the OpenAccess Coalition, designs, measurements, and results were passed back and forth between tools via time-consuming, error-prone, file transfers. OpenAccess in effect “opened” the design database so all coalition members could develop tools that shared the database. This removed the cost of the file transfer and allowed two tools to act upon the same data. While file transfer seems like a small thing, it can represent significant cost-of-engineering time on a large design. In addition, it enables the user to check-fix-check errors one at a time instead of several at a time, reducing long file transfer time. Ultimately it benefitted the entire industry enabling “best of “design flows, which are very common today.

So is OpenAccess open source software?

The answer is no. The difference is who it is open to. OpenAccess is licensed much like open source software, though not open to the general public. The license benefits OpenAccess Coalition members that provide the resources required to keep the standard viable for use by the Coalition. There is a significant resource investment associated with OpenAccess. OpenAccess Coalition members have access to the source code and some of the derivative products (called Extensions) to use and even modify if necessary. Much like the Open Software Foundation works for the general public, Si2 and the OpenAccess Coalition provide a means of collaborative development for design product interaction/interoperability. The really great part is that the members realize a 1/N cost advantage while developing the standard.

Is Si2 OpenAccess “open?”

Yes, OpenAccess is open to the OpenAccess Coalition membership, which consists of many electronic design automation tool development companies, and semiconductor companies. That’s pretty open.

Geoffrey Coram Named New CMC Technical Advisor

Geoffrey J. Coram of Analog Devices is the new volunteer technical advisor for the Si2 Compact Model Coalition.  In this newly created position he advises the coalition on Verilog-A implementation for its standard compact models.

Over the past decade, the preferred language for development and implementation of compact models has shifted from C to Verilog-A. Recognizing the importance of the new language, the CMC officers created this position to assist model developers and help encourage best practices.

A senior member of the IEEE, Geoffrey has been an active CMC participant since 2002 and currently leads the CMC subcommittees on Verilog-A recommended practices and the MOS varactor model. In 2004, he led the efforts of the Accellera Verilog-AMS subcommittee to add compact modeling extensions to that modeling language in Language Reference Manual version 2.2.

Geoffrey joined the internal CAD development and circuit simulation group at Analog Devices after earning a Ph.D. from the Massachusetts Institute of Technology in 2000. His undergraduate degree is from Rice University.