Sun Microsystems on Thursday confirmed reports that it has delayed by a year its long-awaited 16-core Rock processor.

Sun said the release of the next-generation UltraSparc chip was pushed back to the second half of 2009 to give the company more time for testing. The company had hoped to ship the new processor in the second half of this year.

"Rock is an entirely new design and given its uniqueness and complexity, Sun is investing heavily to fully validate the chip and to do advanced testing on the entire hardware and software stack of future systems to be powered by Rock processors," the company said in an e-mailed statement. "Systems based on the Rock processor are expected to be available in the second half of calendar year 2009."

Despite the delay, Sun insisted there were no major technical problems. "Sun continues to evolve its systems portfolio on multiple fronts and early Rock chips are testing well in Sun Labs," the company said.

Rock is the first CPU to implement scout threads and transactional memory. Both features are expected to become increasingly important for multicore processors.

Each of Rock's cores has two simultaneous computing threads and supports up to two scout threads. The latter can pre-fetch, execute, and retire instructions in an out-of-order fashion without using traditional, complex out-of-order memory structures, Mark Tremblay, CTO of Sun's microelectronics group, told EE Times, a CMP publication.

Sun's rivals in the development of next-generation, high-powered server chips include Intel and IBM. Sun released details of Rock at the International Solid State Circuits Conference in San Francisco this week.