The chief scientist of supercomputer manufacturer Cray is leaving to take a job at Microsoft.

Burton Smith will leave the company on Dec. 7 to take the Microsoft job, he informed Cray last Sunday. He will also cease to be a director of Cray on Dec. 7, the company said.

Microsoft has started to show a keen interest in high-performance computing. At the Supercomputing 05 show in Seattle earlier this month, it unveiled the beta 2 version of Windows Compute Cluster 2003, an version of its server OS with additional job-scheduling tools for computing clusters.

Smith was one of the founders of Tera Computer Co., where he served as chief scientist since 1988. Tera bought Cray Research from Silicon Graphics (SGI) in 2000, and renamed itself Cray. On its Web site, Cray credits Smith as the chief architect of its MTA (Multithreaded Architecture) system.

Cray was once synonymous with the world's most powerful computers. Now, though, Cray's proprietary CPU designs are increasingly being supplanted by clusters of commodity microprocessors. According to the latest Top 500 supercomputer list, the world's three fastest computers are all made by IBM, with fourth and fifth places occupied by SGI and Dell Inc. Cray appears in sixth place, and also made four of the other top 20 computers.

Cray announced Smith's resignation Friday in a regulatory filing with the US Securities and Exchange Commission (SEC).