Getting Up to Speed on the Differences in PowerPCs

Apple’s market share may not be growing, but in one important way the Mac market has recently developed pituitary hyperactivity. In recent weeks, the four U.S. clone makers and Apple have announced well over 40 Mac compatibles--more Macs than were produced in the machine’s first decade.

The Mac market now resembles the Dr. Jekyll side of the PC market: competition leading to wider choices. Let’s hope we don’t soon encounter Mr. Hyde--hideously unreliable knockoffs of a once-solid standard.

A cascade of advances in PowerPC central processors largely spawned this proliferation. Until recently, all Macs used Motorola’s 68000-series CPUs--the 68000, 68020, 68030 and 68040. Meanwhile, most PC brains were from Intel’s X86 series--the 286, 386 and 486. The “2,” “3” and “4” in each family indicated increasing performance and rough parity for common tasks.

Intel continued its family with the Pentium. Apple switched to a new chip design in 1994. PowerPC proved vastly more powerful--and confusing--than the venerable 68000 family. Five different PowerPC CPUs that run at more than a dozen speeds have already been released. To put your buying choices in context, here are answers to the most common questions about PowerPC:

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Q What distinguishes one PowerPC chip from another?

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A Books have been written about this question, but as a newspaper columnist I’m authorized to answer in a few words: size, speed, the power they require, the number of microcircuits they boast of and the heat they generate.

The PowerPC 601 processor, used in the original Power Macs, made the Mac competitive. It’s now considered so pokey that only one Mac on the market still uses it. The slightly slower 603 requires less power and generates less heat--perfect for laptops--and it’s cheaper to produce, so it also works for beginner machines.

The 604, the 601’s successor, has become a mainstay in desktop and tower Macs.

The 603e succeeded the 603, just as you find the 604e--at the moment, the fastest CPU for any personal computer--taking over for the 604’s high-end turf.

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Q What does the megahertz rating mean?

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A In general, the faster the CPU, the more capable and costly the machine. The 604e goes from 132 MHz to 250 MHz, with 300 MHz on the horizon; the 603e ranges from 117 MHz to 240 MHz. But speed ratings differ across chips. Megahertz for megahertz, the 604 performs about 40% faster than the 603e (so a 150-MHz 604-based system can outrun a 200-MHz 603e-based machine); the 604e operates about 60% faster.

For serious number crunching, graphics, multimedia or 3-D modeling, go for a 604e-based Mac if you can afford it. For routine home or office computing, a 603e-based machine works fine. (One exception: The intense graphics of some games work best on faster computers.)

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Q Can PowerPC keep pace?

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A For now, the 604e beats anything Intel offers. And PowerPC-based Macs will certainly compete well in the foreseeable future. Two new PowerPC processor series should boost performance to 10 to 20 times that of the 601 as we approach the millennium. (Prepare yourself, by the way, for scads of cliche product names such as “Millennium 2000.”)

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Q Does Intel’s MMX technology warrant fear and loathing?

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A MMX accelerates signal processing, conformal mapping and vector math with multiply-and-accumulate instructions. . . . Yikes! My brain momentarily lapsed into engineering-speak (which can happen when analyzing Intel products).

In plain English, MMX, due out by the end of the year, should speed up multimedia and 3-D graphics on Pentium boxes. Intel has made grand but as-yet-unproven claims for MMX that are disputed by the PowerPC folks, who nonetheless seem a bit worried. And Apple is preparing add-on cards to compete with MMX. So it goes in the processor wars.