Supercomputer pioneer Seymour Cray battled for his life today after breaking his neck and severely injuring his head in a traffic accident blamed on a careless driver.

Cray, 70, was in critical and unstable condition at Penrose Hospital, spokeswoman Kate Brewster said. He underwent surgery to relieve brain swelling after the accident Sunday.

Cray's Jeep Cherokee rolled three times after the driver of another vehicle tried to pass him and struck another car, which slammed into Cray's vehicle. The other motorists weren't injured.

Daniel Rarick, 33, of Colorado Springs was cited for careless driving that caused serious bodily injury, said Colorado State Patrol Sgt. Rob Wilson.

Cray, who devoted his life to trying to develop the world's fastest supercomputers, is a legendary figure in the industry.

"He is the Thomas Edison of the supercomputing industry," said Larry L. Smarr, director of the National Center for Supercomputing Applications at the University of Illinois.

"We wouldn't have the kinds of airplanes and cars that we have now if it hadn't been for him," said John Rollwagen, chairman of Computer Network Technology Corp. of Plymouth, Minn.

Supercomputers, which calculate billions of scientific problems per second, are used for weather forecasting, automobile crash simulation, oil exploration and drug research.

In 1957, Cray co-founded Control Data Corp., where he built the first computer to use radio transistors instead of vacuum tubes. The transistors made the machines more reliable and allowed for the miniaturization of components, which enhanced the performance of desktop computers.

In the 1960s, he designed the world's first supercomputer at Control Data, then left in 1972 and co-founded Cray Research Inc.

There, he built the Cray-1 and Cray-2 supercomputers, which helped the defense industry create sophisticated weapons systems and the oil industry construct geographic models that predicted mineral deposits.

At his third company, Cray Computer Corp., he failed to raise $20 million for operating costs and filed for bankruptcy in March 1995. It closed soon afterward. In August, Cray started a new company called SRC Computers Inc. CAPTION: SEYMOUR CRAY