I've thoroughly read [the Wikipedia article on DNA sequencing][1] and can't get one thing.

There's some hardcore chemistry involved in the process that somehow splits the DNA and then isolates its parts.

Yet DNA sequencing is [considered to be a very computationally-intensive process][2]. I don't get what exactly is being computed there - what data comes into computers and what computers compute specifically.

What exactly is being computed there? Where do I get more information on this?


  [1]: http://en.wikipedia.org/wiki/DNA_sequencing
  [2]: http://www.genome.gov/sequencingcosts/