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GDSII Info, Links
What is GDSII
GDSII is a binary file format which is classified as a "data interchange format", used for transferring mask-design data between the IC designer and the fabrication facility ("Fab"). At the Fab, the GDSII data is converted into a machine-readable language called CATS (for Computer Aided Transcription Software) which transcribes the data so that it can be read by the photomask systems used in the manufacture of semiconductors.
GDSII stands for "Graphic Design System II". Alternative names are "Calma Stream Format" (CSF) or just "Stream Format". Alternative spellings to GDSII you might encounter on the Net: GDS, GDSIII, GDSIV, GDS2, and various alternatives with a dash or space between the "GDS" and number part.
The GDSII format was invented in the early 1970's at Calma Co. in Sunnyvale, Calif, a then wholly owned
subsidiary of General Electric Company, U.S.A.
Because it has become an EDA industry standard, GDSII is an open standard- you can even find open-source libraries and tools on the Net (but more on that in the next section). Apart from that, you can also read about the file format from several places, which provide descriptions ranging from the general to specific technical details and the BNF for the GDSII format. For example:
There are many companies which offer free GDSII tools or free demo versions of commercial tools. A number of examples are listed below. If you know of a good tool that is not listed, please let us know.
Free GDSII Viewers
GDSII Conversion Utilities
Other GDSII Tools
The Future of GDSII
There's a problem with GDSII -- it's OLD. The format was not designed to compactly handle the amount of data a modern layout requires, a problem that can cause modern GDSII files to reach as much as 50GB in size. In fact, this problem was already considered severe enough for a paper titled GDSII Considered Harmful to be published in October 2001. So what's to be done? Well, the above paper suggests improvments to the GDSII format, or even a replacement based on XML.
However, an organization called SEMI has decided to replace GDSII with a new format, called OASIS(*), for "Open Artwork System Interchange Standard". The OASIS specification, SEMI P39-0304E2, is available for online purchase.
It now remains to be seen how wide industry support will be for OASIS. As there are currently no other contenders for the crown of GDSII replacement, OASIS seems like it will eventually catch on.
*OASIS is a registered trademark of Semiconductor Equipment and Materials International.