Analysis: Inside Core Duo

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Mac users have heard plenty about the new iMacs and MacBook Pro that mark Apple’s first releases to run on chips from Intel. But what about Core Duo, the processor inside these new systems?

Here’s a few quick facts about the Core Duo. It’s one cool customer. It talks to software super-quickly. Its design leaves plenty of room to grow. And for those of you who dream of a supersonic Mac, some analysts predict Intel will leap from the two processor cores you see in Core Duo to four-core processors by 2008.

Keep your cool

The Intel-based iMacs use 1.83 GHz and 2GHz versions of Core Duo, a chip designed specifically for notebooks and small form-factor desktops.

Compared to the PowerPC chips in the most recent iMacs and notebooks, Core Duo’s key strength is its ability to keep its cool while throwing more computing power at software. In Core Duo, Intel essentially combined two Pentium M chip cores into one physical package. (Intel built Pentium M from the ground up for mobile machines, with low power consumption as a priority.)

As Mac users know, dual-processor PowerPC desktops need special cooling systems, since the two chips generate so much heat. And Apple never has been able to make the G5 chip work in a notebook, because that processor runs so hot.

Faster system bus

Core Duo gives Apple users the power of two speedy CPUs, which will be of particular help when your machine multitasks. For example, the system can throw the smarts of one CPU at a background task like backup, and throw the other CPU at a demanding application like video-playback. But just as notably, Core Duo delivers a much faster system bus compared to previous PowerPC chips. Core Duo’s system bus—the main road for software requests traveling to and from the CPUs—runs at 667 MHz, while the G4’s runs at 167 MHz.

The new iMacs combine this much-improved bus with faster graphics and hard drive technology compared to previous iMacs—making “the whole experience noticeably faster and more responsive,” says Kevin Krewell, editor-in-chief of In-Stat’s Microprocessor Report.

The MacBook Pro laptops will use 1.67GHz and 1.83GHz versions of the Core Duo. These chips take Apple notebooks to a new speed lane, while ensuring room for continued design innovation, due to low power requirements.

Core Duo provides roughly five times as much performance per watt of power consumption as the G4 or G5 chips, Apple’s Steve Jobs told Macworld Expo attendees earlier this week.

One Core Duo performance “gotcha” lingers, temporarily: Since Intel’s instruction set differs from PowerPC’s, software vendors must release revamped applications before users will see maximum speed from the apps.

Some vendors are working on “universal” software versions designed to run at peak speed with either PowerPC or Intel chips, Jobs says. Older software will run, using the Rosetta emulation technology, but you won’t see peak responsiveness under Rosetta. ( Macworld ’s latest FAQ about the Intel transition discusses this issue in further detail.)

Revamped versions of Apple’s operating system and its new iLife and iWork software are ready now. As for your other favorite apps, you’ll have to wait and see: Apple is transitioning to Intel faster than expected, so software makers may also hop to it.

Coming soon: a handheld Mac?

Looking ahead, Core Duo has plenty of room to grow, In-Stat’s Krewell says. “Core Duo can go both higher and lower power,” he notes. That means Intel can crank up the power if necessary to crank up the speed, or lower the power for special case designs.

What does this mean for iMac fans? “You could see a handheld Mac a couple of years in the future,” Krewell says, “something larger than a PDA, but smaller than a notebook. No one has been successful with such a device, but that is not to say that Apple couldn’t do a better job.”

Up next, Intel’s “Merom” chip, coming in the second half of 2006, builds on Core Duo’s design but adds enhancements including support for 64-bit computing.

Intel won’t stop with putting two cores on one chip. “Intel will likely go to quad-core processors no later than 2008,” Krewell predicts. Imagine what an iMac could do with that.

This story, "Analysis: Inside Core Duo" was originally published by PCWorld.

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