Brent Schlender of Fast Company has written a great long-form article on Steve Jobs's so-called "wilderness years" -- the period between when Jobs was ousted from Apple in the mid 80s and his return in the late 90s. Many people (wrongly) tend to think of this period as Jobs sort of aimlessly drifting until his triumphant return to Apple, but Schlender convincingly argues that it was during this time that Jobs grew into the sort of businessman who could not only bring Apple back from the brink of bankruptcy, but transform it into the world's most valuable company.
Jobs was indeed busy during that decade, founding NeXT and helping to transform Pixar into a giant force within the entertainment industry. While Walter Isaacson's biography of Jobs goes into the details of this period of Jobs's life, Isaacson seems to treat both NeXT and Pixar as diversions or distractions from the bigger goal: Apple. Schlender instead argues that Steve Jobs brought the same devotion to those two companies that he brought to Apple, and his work at both companies made him into exactly the CEO Apple needed.
Schlender's article is quite long, but it's a very good read. If you can, set aside some time and read the whole thing.