The processor will have a new, multi-threaded design and double the core count from Sun's fastest server processor today, the UltraSparc T2, which has eight cores. It will be targeted at enterprise servers that process data-intensive applications like databases.

"The processor is in various stages of debug. We're getting close [to release]," said John Fowler, executive vice president of systems at Sun, in an interview.

Fowler didn't provide an exact ship date but said the chip will be in servers by the Fall, suggesting a September to November timeframe. Rock was originally due for release in 2008, but Sun revealed last year that it had delayed the release until the second half of 2009.

The first 16-core chips will go into midrange servers, Fowler said. Sun currently offers a four-socket mid-range server called the Sparc Enterprise T5440, which uses the UltraSparc T2 processor, and Rock will debut in a system "above" the T5440, Fowler said.

"They are not going to be necessarily someone's first purchase but they'll fit nicely into the midrange where a lot of enterprise-level databases and fairly significant amounts of processing will live," he said.