Sun Microsystems has taken another step towards open-source by releasing the source code for its UltraSparc T1 processor.

The strategy is part of Sun's OpenSparc Initiative, a move to create the world's first multicore, multithreaded ecosystem.

Sun advanced that effort in February when it released its Hypervisor API specifications. That move allowed companies to port Linux, BSD and other operating systems to UltraSparc T1 and gave developers the information they needed to create related hardware and software tools.

Now Sun has continued the initiative by publishing the hardware design point and the Solaris 10 OS porting specifications for the processor.

Those specifications grant developers access to the chip's multithreading (CMT) technology, a 64-bit, 32-threaded processor design that the company is calling "OpenSparc T1." It is available free under the GNU GPL (general public license).

"Sun is using open standards and the creation of a rich CMT community to foster innovation and maintain our multiyear lead over competitors in delivering multithreaded systems to customers," said David Yen, executive vice president for the scalable systems group at Sun.

Sun first announced its OpenSparc programme to publish specifications for the UltraSparc T1 chip, formerly code-named Niagara, last December. The company described that move as "open sourcing" hardware, and positioned the program as a way to eventually have third parties improve on the processor's design and produce their own UltraSparc T1-based chips.

This is a rare move in the chip market, but that is not because it's risky, analysts said. Rather, other chip manufacturers have not tried the strategy simply because they don't need to change user perception.

"Neither Intel nor AMD needs to convince people that x86 is a viable, long-term architecture," said Nathan Brookwood, an analyst with Insight64. "Whereas for Sun, even though they are still the most prolific RISC-based architecture if you count systems, people still wonder if there is a future with Sparc."

On the upside, Sun has created an opportunity for developers to get involved with the Sparc system, whether it's universities doing studies or engineers building new systems in developing countries like India, China or Hungary. Meanwhile, no one anticipates that Sun's rivals - such as Intel, IBM or AMD - will download the code and ship competing Sparc-based servers, he said.

Sun has published the OpenSparc T1 chip design and verification suites, architecture and performance modeling tools online. The company has also posted programming tools.