What processors do the MacBook Air models 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 uses "existing Core 2 Duo technology with a lower voltage spec in a new miniaturized packaging design."

Subsequent MacBook Air models are far less mysterious, although Apple has not released the actual Intel processor number for any of the systems. EveryMac.com documents the Intel processor number for all MacBook Air models on the main MacBook Air specs page as well as on the specs page for each model.

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

The original MacBook Air has 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 is soldered in place and cannot be upgraded in these MacBook Air models.

The "Late 2010" MacBook Air models, on the other hand, could be upgraded from a stock 2 GB of RAM to 4 GB of RAM for US$100, but only at the time of purchase. The entry-level "Mid-2011" MacBook Air model -- the MC968LL/A configuration of the MacBook Air "Core i5" 1.6 11-Inch (Mid-2011) -- has 2 GB of RAM standard and could be upgraded to 4 GB only at the time of purchase for an extra US$100. All other "Mid-2011" MacBook Air models have 4 GB of RAM soldered in place and cannot be upgraded at all.

The current "Mid-2012" MacBook Air models ship standard with 4 GB of 1600 MHz DDR3L SDRAM soldered in place and can be upgraded to 8 GB of RAM, but only at the time of purchase for an extra US$100.

Those who want to be able to upgrade the RAM after purchase should instead purchase a pre-Retina Display 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 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 originally only was intended to work with the MacBook Air line, although Apple subsequently made it available for the optical drive-less aluminum Mac mini models and Retina Display-equipped MacBook Pro series.

At the time the MacBook Air SuperDrive was released, some decided to speculate that the USB 2.0 port(s) in the pre-"Mid-2012" MacBook Air models had been "boosted" to provide extra power beyond that provided by most other Macs. Further 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. More recently, as first reported by TUAW, Lukas Zelller discovered a software method that simply involves editing a single line in a text file. This simple edit still could cause problems with operating system updates, however.

Ultimately, the external MacBook Air SuperDrive will not work with incompatible Macs without hacking and Apple obviously does not support hacking whether hardware or software, either one.