Centrino Mobile Technology Evaluation

By Andy Patrizio

August 4, 2003

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I know, I know. I promised a column on cooling. Well, the stars didn't line up in time for this month, and I had this super laptop sitting on the lab bench (which mysteriously looks a lot like my dining room table) for weeks, so it was time to take a peek at Intel's big mobile push.

Intel has been making laptop chips since the 1980s, but those chips have always been a desktop product that was whittled down a little to operate in a notebook. In recent years, Intel has moved to concurrent development of notebook chips with desktop chips. For example, all P4 chips coming off the line with SpeedStep built in, but only chips planned for notebooks have it enabled.

Notebook performance speeds have lagged behind desktops for one reason: heat. The heatsink and fan on my 3.06 GHz Pentium 4 is taller than a lot of notebooks, and this beast is still an oven. Intel created the Centrino chip from scratch to be a mobile chip, rather than taking a desktop chip and reducing the voltage and frequency.

The Centrino chip is as much a Pentium III as a Pentium IV because Centrino uses a shorter pipeline. The P4 has a longer processing pipeline, which is used to predict the path taken in a piece of code being executed. In other words, it makes an educated guess at the result, such as the outcome of a statement.

If the P4 guesses wrong, it has to execute that code all over again, which means more cycles being used up. For a desktop computer, no big deal, it's plugged into the wall. For the notebook, that means power consumption.

This made the P4 seriously unusable as a notebook computer. The P3, though, ran out of gas at 1.2 GHz. So Intel's designers made a compromise, extending the P3 core and creating a CPU that's somewhere between P3 and P4.

Intel has made things pretty confusing with all its mobile products. There's the Mobile Pentium 4 processor, the Mobile Pentium 4 ProcessorM, Mobile Pentium III Processor-M, Pentium M Processor and Mobile Celeron Processor. Intel will phase out the P4-M, which is the older version of the product, while the Mobile Pentium 4 will remain for laptops designed as desktop replacements.

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