In addition to the Protocollum tool, which allows communications systems engineers to capture, edit and test a protocol architectural specification, Bellum is bringing a familiar name back to the EDA industry. Bob Hunter, former president of HDL simulation pioneer Model Technology, serves as the Hillsboro, Ore., company's vice president of marketing and sales.

Christensen, the president of Bellum Software, is basing his new company's tool on observations gleaned from 12 years at Intel. "The issues we had at Intel about how you write clear specifications for validation, and how they get communicated, are still around and we haven't made a lot of progress," he said. "My impression is that most teams are using homegrown tools or are using various languages to write their own models. There doesn't appear to be much of an effort in trying to do that in a graphical or visual way."

After leaving Intel in 2001, Christensen said, he came across a paper from an IBM Corp. research group in Zurich, Switzerland, that showed there might be a better way to model communications protocols.

Christensen had been concerned about this issue, he said, because of a realization that most bugs occur in the interfaces between functional units. He originally thought that message sequence charts might be a good way to model communication between units, but these are primarily static diagrams drawn in PowerPoint or Word. "What I wanted was an executable running system, where you could change diagrams on the fly," Christensen said. "What I got out of the [IBM] research paper was an approach to doing that. Basically, they had a rule-based system that allows you to create and plot events in a graphical environment."

He developed Protocollum on his own, and only recently began talking to some marketing people and developing a Web site at www.bellum.biz. Christensen then approached Hunter as an adviser, and so impressed Hunter that he set aside his seven years as a "gentleman farmer" to join the self-funded startup.

"I'd been doing this and that, but nothing really in the professional world," Hunter said. "This is just a very, very interesting tool that might offer a lot of value. I found it really intriguing. And I think I have enough background with enough contacts to make a little headway and get some exposure with engineering groups in the U.S."

Bellum's overall mission, said Christensen, is "putting good tools in the hands of computer architects." Protocols are a good place to start, he said, because they're so pervasively used and because there's been little progress in how they're developed.

Today, said Christensen, most people model protocols by designing state machines in languages like C, SystemC, VHDL or Verilog. Protocollum allows the same thing, he said, although it takes place in a graphical environment. "If you're writing lines and lines of code, you can't see or visualize what the flow of the system is," he said.

Protocollum allows designers to set up much of their system through point-and-click operations. State machines do need to be specified in code, which is done through Tcl scripting. But even that, said Christensen, becomes input for a graphical model.

Once an architecture is captured, users have an executable specification. Users can set up a "test sheet" that establishes various message-passing scenarios. By observing states, they can see if the system is behaving as they expected.

Christensen said that early adopters have mostly been hardware engineers, although the tool could be used prior to hardware/software partitioning. There is, however, no direct connection to downstream implementation, since Protocollum does not generate SystemC or HDL code.

At a time when many EDA tools cost upward of $100,000, Protocollum has what may be a refreshing price tag — $995. Some of the distribution will be through the company's Web site. "We're starting out small," Hunter said. "We're not going to overmarket this thing."

Christensen gave Protocollum a road test himself on the 802.11 specification, finding a bug in that 1999 specification in the process. But the tool isn't just about large, well-known communications protocols, he said. "Chip design has plenty of communications in it. We just haven't been too formal in how we specify that and pass it to other designers."