I've been hearing from a lot of readers about a recent article, "Free software catches spark in EDA world". First, many people are pointing out that software based on the GNU Public License (GPL) can in fact be resold, and second, readers are pointing out additional open-source EDA projects or products accessible from the Internet. So much is going on that it's getting hard to keep track of it all.
My initial statement that GPL-based source code cannot be resold drew fire from many vigilant readers, who noted that you can in fact take GPL software, modify it and sell it-so long as you provide source code on request, without restricting its use or distribution. As the Free Software Foundation's Richard Stallman puts it, "think free speech, not free beer." The freedom is the ability to get your hands on the source and do as you wish.
There's also a lot of free EDA software out there that's not under GPL terms. V2000 is a new project to develop a free Verilog-AMS simulator that will probably not be placed under GPL. The University of California at Berkeley offers EDA tools under its own licensing scheme.
The best single reference to "free" or open-source EDA software I've found is the Web page www.wmin.ac.uk/~seamang/freehardware.html. To avoid filling this column with long URLs, you can assume that everything mentioned here is accessible from a link on this page.
My initial article mentioned Gnu EDA (gEDA), a GPL-based project to develop a schematic editor, and FreeHDL, a GPL-based project that's building a VHDL simulator. Add to this list Xelen PCB, a project launched by a graduate student in Germany that now has some GPL alpha code for pc-board schematics and layout.
More ambitious, perhaps, is Open Design Circuits, which is seeking to design a low-cost FPGA architecture and tools. If you want really ambitious, try the Freedom CPU Project, a multinational effort to design a GPL 64-bit processor.
You'll go well beyond alpha code with the GPL-based Alliance VLSI design system, which has been around for several years and is in use by some 250 universities. It includes simulation, synthesis, layout, design-rule checking, timing analysis and many utilities.
Other GPL-based software includes the Voyeur visualization tool, Vaul VHDL analyzer, Simsynch digital simulator, Thud RTL simulator and Veripool Verilog waveform viewer, among others.
Is open-source EDA software as usable as commercial tools? Does it extend beyond academia? If you're working in industry and using such tools, I'd like to hear about it at rgoering@cmp.com.
