Under the G4's hood

What's so special about the new Macs? The basic specs for the Power Mac G4 Cube desktop computer are pretty typical: 128M RAM, 450 MHz processor, 20G hard drive, CD-RW drive, two IEEE 1394 FireWire ports and two USB ports, 10/100Base-T Ethernet adapter and a 56K V.90 modem. A 500 MHz processor is available.

For power users, the Power Mac G4 packs faster processors than the G4 Cube into a roomier tower cabinet that has been expanded from previous models to include one more PCI expansion slot, bringing the total to four. Processor speed tops out at 733 MHz.

If anything, these specs are almost prosaic; the processor runs at less than half the top speed of Pentium 4 chips these days. But the PowerPC G4 processor is built using a RISC (reduced instruction-set computing) design, so it can do more work per clock cycle than a traditional CISC (complex instruction-set computing) chip like the Pentium.

RISC chips traditionally excel at floating-point operations, the kind of work done by technical work-stations, and when performance is measured in millions of floating-point operations per second (megaflops), the Apple easily tops the Intel-based competition. In today's computing environment, common tasks such as processing Adobe Systems Inc. Photoshop image filters and encrypting online trans-actions are creating a demand for that kind of processing power. The G4 performs more than 1,000 Mflops, moving it into the realm of gigaflops. That territory was once the sole domain of super-computers — incredibly expensive and notoriously finicky machines.

"The PowerPC chip was designed with high performance in mind," said Will Swearingen, director of strategic communications for Motorola Inc., which makes the processor. "You are getting a lot more work per clock cycle than with an [Intel] X86 chip." Nevertheless, the company is scrambling to get a 1 GHz chip out soon, he said.

The G4 processor also features what Apple calls the "Velocity Engine," which refers, somewhat grandiosely, to the chip's 128-bit design. That lets it take 128-bit bites out of work, instead of processing in 32- or 64-bit chunks.

"There is no question it runs so much faster" than previous models, said Ed Baroth, technical manager of the instrumentation department for NASA's Jet Propulsion Laboratory. Mac users in his department use their machines to run typical office productivity applications, to generate reports and to display data acquisition from spacecraft, he said.

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