If you thought that the IA just archived paper books then I have news for you.
In the late 70s and 80, Cray Research Corporation made a number of one of a kind supercomputers. They were incredibly powerful for their day and they were incredibly expensive. Of course, you now have more computing power in laptop than any Cray models, but that's what happens with technology.
The amazing part here is not on did they have to figure out how to interpret the data on the magnetic disks, they also had to build a rig just to read the disks. In fact, they haven't decoded the contents yet; all that is online at the moment are images taken from the raw scan of the 5 platters. And I do mean the raw disk images; that 80MB disk drive now takes up 5GB of ZIP files on one of IA's servers. UnZip them and you'll have 20GB of data to play with.
You can read the full report on how finally got the data here; it makes for fascinating reading from a techno-archeology point of view.