Richard Partridge, an analyst at Ideas International in Port Chester, N.Y., said that there is more than hardware timing involved for Sun customers in a decision to buy an APL or a Rock processor.

Sun is betting that there will be an adequate number of parallel applications by mid-2008 and beyond that will be able to take advantage of Rock's multicore design. It could well turn out in mid-2008 that a large number of its customers will need the APL UltraSparc, because their applications can't utilize large numbers of cores. For those users, a decision as to what chip to upgrade to will depend on what applications it will support, said Partridge, who said Sun may not feel confident enough just yet to predict the application outlook.

By offering APL as well as Rock, Sun is "moving in a direction that they believe is the right direction, but they at least recognize that they need a fallback plan," said Partridge.

In other chip developments, Sun will detail sometime this year its end-of-life plans for UltraSparc IV and IV+. It will also release a new version of its multicore Niagara chip, which is aimed at workloads such as Web servers.

Niagara has eight cores with four threads per core, but Niagara 2, which will be released sometime this summer, will remain eight cores but with eight threads per core, as well as more networking and cryptologic functions, said Tremblay.