In the spring of 1975, a college dropout and his childhood friend launched a tiny software company in Albuquerque with a singular mission: put a computer on every desk and in every home. Five decades later,

When Bill Gates and Paul Allen founded the company they called Micro-Soft 50 years ago this week, it was to sell a version of the Basic computer language for the Altair, the first proto-PC. Their first product set the pattern for what was to follow.

Microsoft has been an icon of technology: innovative, ruthless in its pursuit of leadership and absorbing the blows in an ever-evolving landscape. With Windows, it became a household name, and literally redefined the office with its eponymous suite of Word,