What processor does the MacBook Air use? Is it upgradable?

Officially, Apple only revealed that the original MacBook Air has a 1.6 GHz or 1.8 GHz Intel Core 2 Duo processor (P7500 or P7700) and was "custom-built to fit within the compact dimensions of the MacBook Air". Apple also provided the following image to compare the size of the standard Intel Core 2 Duo processor to the one in the MacBook Air.

The always excellent AnandTech did some digging and discovered that the "packaging technology used for this CPU is what makes it unique; the CPU comes in a package that was originally reserved for mobile Penryn due out in the second half of 2008 with the Montevina SFF Centrino platform. Intel accelerated the introduction of the packaging technology specifically for Apple it seems."

After AnandTech published their initial speculation, Intel followed up with their own statement, noting that the original MacBook Air "is using existing Core 2 Duo technology with a lower voltage spec in a new miniaturized packaging design."

The "Late 2008/NVIDIA" MacBook Air models are far less mysterious, using either a 1.6 GHz (SL9300) or a 1.86 GHz (SL9400) "Core 2 Duo" processor. The "Mid-2009" MacBook Air models likewise are not mysterious and are powered by either a 1.86 GHz (SL9400) or 2.13 GHz (SL9600) "Core 2 Duo" processor.

How do you upgrade the RAM in the MacBook Air? How much RAM of what type does it support?

The original MacBook Air comes with 2 GB of 667 MHz DDR2 SDRAM onboard and the "Late 2008/NVIDIA" and "Mid-2009" models have 2 GB of 1066 MHz DDR3 SDRAM onboard. The RAM cannot be upgraded in any MacBook Air model.

Those who need greater memory capacity should instead opt for a MacBook or MacBook Pro.

What are the capabilities of the external SuperDrive available for the MacBook Air? Can it be used with other Macs?

The external SuperDrive that is available for the MacBook Air for US$99 writes DVD+R DL and DVD-R DL at 4X, DVD-R and DVD+R at 8X, DVD-RW at 6X, and DVD+RW at 8X. It reads DVD at 8X, writes CD-R at 24X, writes CD-RW at 16X, and reads CD at 24X.

The external MacBook Air SuperDrive is not designed to be used with other Macs. Some decided to speculate that the USB 2.0 port in the MacBook Air has been "boosted" to provide extra power beyond that provided by other Macs. Speculation from AppleInsider concluded that the MacBook Air SuperDrive could work with other Macs if not for software restrictions and states that it is possible "Apple is offering the drive as a loss leader convenience for Air users, and doesn't want to support the drive on other systems because it's not making any money on it."

However, after a truly "überleet" hardware hacking session, tnkgrl eliminated "power boosting" and software restrictions as possible variables -- as well as others -- and discovered that replacing the IDE to USB bridge with another one (for US$9) made it possible to use the MacBook Air SuperDrive with other computers.

Ultimately, the external MacBook Air SuperDrive will not work with other Macs without serious hacking and Apple obviously does not support hardware hacking.