I'm seeing a lot of confusion on the web as to why Apple has limited the MacBook Air to only an 80Gb disk, when say a 160Gb 1.8" disk exists (and is used in the iPod classic). My guess is that the reason why Apple is sticking with 80Gb is that this is the largest 1.8" drive that you can get that fits on one platter.
For hard disks, a common trick to increase capacity is to add platters - the physical media where the data is stored. They'll be stacked, one on top of another, inside of the disk enclosure. This is all well and good, but it makes the drive physically thicker.
My guess is that every millimeter counted in the MacBook Air, so Apple needed to find a disk that was no more than 5mm tall. All of the larger 1.8" disks that I looked at today are two platter designs, that come in at around 8mm tall.
If you look at the specs for the aforementioned iPod classic, you'll see that the 80Gb and 160Gb models are the same dimensions, except for depth - where the 160Gb model is exactly 3mm ticker. Those extra millimeters can be attributed to the extra platter inside of the 160Gb disk.
After doing some digging, I think I have found the disk that Apple is using - the Samsung Spinpoint N HS081HA - it is a 1.8", 80Gb disk, that is only 5mm tall.
Update: I went back to MWSF today, and managed to take a "spy photo" of system profiler on the new MacBook Air. It looks like I was right:
You can clearly see the Samsung HS082HB drive powering the MacBook Air demo model at the Apple booth at Macworld.
-Andy.
Technorati Tags: Apple, MacBook Air, Hard Disk, Samsung, Spinpoint N, iPod classic