The ultraportable MacBook Air was introduced in July 2008.
All MacBook Airs have had no internal optical drive, fixed
(non-upgradeable) RAM, and a 1.8" form factor SSD or hard
drive. The original MacBook Air
had a 13" screen, a 1.6GHz or 1.8GHz Intel Core 2 Duo
CPU, and used 1.8" IDE type drives. Apple's specs here.
With the second revision in October 2008, the range moved
to a SATA type 1.8" drive. The screen size was 13" and
there were 1.6GHz and 1.86GHz Core 2 Duo CPU options. Apple
The line was refreshed in June 2009, with CPU options increasing
to 1.86GHz and 2.13GHz Core 2 Duo. Apple specs here.
With the October 2010 revision, Apple introduced the smaller
11" screen model while still selling the 13". The 11" model
had 1.4GHz and 1.6GHz Core 2 Duo CPU options, while the 13"
had 1.86GHz and 2.13GHz. Apple specs here for the 11" and here for the 13".
The July 2011 moved to 1.6GHz Core i5 and 1.8GHz Core i7 options
on the 11" and 1.7GHz Core i5 and 1.8GHz Core i7 for the 13".
Apple specs here.
There was an Education only model released in early 2012,
but the next full revision was June 2012 which saw a 1.7GHz
Core i5 and 2.0GHz Core i7 for the 11", and 1.8GHz Core i5
and 2.0GHz Core i7 for the 13". Apple specs here.
In June 2013 new revisions were introduced. The headline specs
were similar to the previous revision with both the 11" and
13" having dual core 1.3GHz Intel Core i5 CPUs as standard,
with a dual core 1.7GHz Core i7 as a Build to Order option.
Both models had 4GB of RAM as standard with an 8GB option -
not upgradeable after purchase. But internally there were significant
changes, with upgraded graphics and much extended battery life.
Also the SSD was changed from a SATA type to PCI Express, allowing
for performance gains on drive of 2x - 2.5x. Apple specs here for the 11" and here for the 13".
In April 2014 the line was refreshed with slightly faster CPU speeds, with both 11in and 13in models sold with a 1.4GHz Core i5 processor, with a 1.7GHz Core i7 Build-To-Order option. Apple specs here for the 11in, and here for the 13in.
Another refresh in March 2015 kept the same case design, but had significant
upgrades to CPU and GPU architecture, and the Thunderbolt ports upgraded
to Thunderbolt 2. Both 11in and 13in revisions were shipped with a 1.6GHz
Core i5 CPU, with a 2.2GHZ Core i7 available as a Build-To-Order option.
Apple specs for the 11in here,
and the 13in here.