Apple rolls out dual 64-bit G5

SAN FRANCISCO — Apple Computer and IBM Corp. on Monday (June 23) disclosed details on what the two companies called the world's fastest desktop computer: a Power Mac with two 64-bit PowerPC processors running side by side.

By doing so, Apple claims to be the first to bring 64-bit computing down to the mass-market level. Three versions are expected to start shipping in August, two based on a single processors running at 1.6- and 1.8-GHz and one dual-processor system, each running at 2 GHz. Prices will range from $2,000 to $3,000.

At the heart of the system is the PowerPC G5, a modified version IBM's high-end Power architecture. The processor includes a revamped execution core that can process 215 instructions simultaneously. Other features include support for symmetric multi-processing, two floating point units and an improved vector processing engine.

IBM will manufacture the G5 at its newest production facility in East Fishkill, N.Y, making it one of IBM's first chips to be produced in volume using 300-mm wafers. The chips will be based on 0.13-micron design rules and take advantage of performance-enhancing silicon-on-insulator technology.

IBM will also produce a special northbridge chip, which was designed by Apple, that links the processor to the memory subsystem and I/O. The processor will be able to send and receive data to this chip through its front-side bus interface at 1-GHz, six times faster than the front-side bus for the previous G4 processor.

The northbridge chip also has two channels extending out to DDR DRAM memory running as high as 400 MHz. The top-of-the-line and mid-range Power Mac G5s can accommodate up to 8 gigabytes of memory spread over eight memory modules.

Apple claims the Power Mac G5 beat Pentium 4- and dual Xeon-based systems in three out of four SPEC CPU benchmarks. For integer performance, the PowerMac was 10 percent slower than Pentium 4 systems in one case and 3 percent better in another test. It's most impressive score was for floating point performance, which was 21 to 41 percent faster than Intel-based systems.

"This machine is a floating point monster," said Jon Rubinstein, Apple's vice president of hardware engineering. "Our developers and creative content customers want that kind of performance and capability."

Importantly, G5 will work with all 32-bit software that runs on its current G4 systems. The performance for 32-bit applications is "very good," Rubinstein said, though he didn't elaborate. Applications designed for 32-bit systems can experience further performance gains if they are recompiled, which in one case took as little as 15 minutes. Developers that tune their applications for 64-bit computing from the start can expect even more performance gains, Rubinstein said.

The Power Mac G5 will ship with the Jaguar OS, which includes extensions that will allow it to support larger memory capacities and new math libraries, Rubinstein said.

Such computing power, however, comes with a price in terms of heat dissipation. Each G5 dissipates 97 watts, which generates so much heat that Apple had to design a new enclosure with four independently controlled thermal zones, each with its own fan. Even so, Apple says it makes half as much noise as its earlier G4 systems.