Apple's new MacBook Air subnotebook raised eyebrows by using a mysterious new, ultra-compact Core 2 Duo processor. New research, however, reveals it to be a blend of old and new technology designed to make few sacrifices.

An in-depth study of the design by AnandTech founder Anand Lal Shimpi explains that the processor is actually based on Intel's 65 nanometer (65nm) Merom architecture with an 800MHz bus, first released in May of last year. All of Apple's current iMac, MacBook, and MacBook Pro models use some form of the processor at a higher clock speed.

But rather than struggle to fit the hot, standard-sized processor package into the tight confines of the Air's chassis — a feat deemed impossible by Jobs during the computer's introduction — Apple appears to have called on Intel to accelerate the release of an extra-small chip package not scheduled to arrive until the launch of the Montevina notebook platform in mid-2008.

"The MacBook Air uses the Intel Core 2 Duo Processor and Intel 965GMS chipset with integrated [graphics] using a new miniaturized package technology. This new CPU and chipset allows for approximately 60% reduction in total footprint," Intel explains in a response to the technology site.

The mixture of current and next-generation parts creates an unusual blend of performance characteristics. The new Core 2 Duo slots just above the Low Voltage (LV series) variants in terms of clock speed and power use — starting at 1.6GHz with 20 watts of thermal design power versus 1.4GHz and 17 watts — but is considerably more efficient than the regular mobile processor, which consumes 35 watts of peak power at a minimum 1.8GHz.

Apple may have been making "tradeoffs" to get the finished MacBook Air on the market in time, Lal Shimpi speculates.

As for the reason behind choosing the new variant instead of stock low or ultra-low voltage Core 2 models, the report suggests only that Apple's main concern was to avoid the low speeds of these chips while compromising as little as possible on energy efficiency or heat.