April 12, 1976: Apple’s third co-founder, a former Atari colleague of Steve Wozniak’s named Ron Wayne, cashes in his Apple shares for just $800.

Wayne, who owns a 10% stake in the company, throws in the towel after worrying that he doesn’t have the time or energy to properly invest in Apple. He later receives an extra $1,500 check to seal the deal. When he cashes it, he loses out on an investment worth billions.

“I was 40 and these kids were in their 20s,” Wayne told Cult of Mac decades later, referring to Wozniak and Steve Jobs. “They were whirlwinds — it was like having a tiger by the tail. If I had stayed with Apple I probably would have wound up the richest man in the cemetery.”

April 11, 1976: Apple releases its first computer, the Apple-1.

Designed and hand-built by Steve Wozniak, the computers are sold wholesale by “Steven” Jobs. To finance their manufacturing, Wozniak sells his HP-65 calculator for $500, while Jobs sells his VW van. Years later, in 2014, a working Apple-1 will sell at auction for $905,000.

April 4, 1975: Childhood friends Bill Gates and Paul Allen found Microsoft Corporation, a software company destined to become a tech behemoth — and a major Apple frenemy.

A few years later, Microsoft will break through to the mainstream with Excel and Word, becoming a key developer of Macintosh software. Then comes the Windows operating system, looking suspiciously Apple-like. After that, Microsoft and Apple will embark upon a long-running feud.

April 1, 1976: The Apple Computer Company gets its start as founders Steve Jobs, Steve Wozniak and Ronald Wayne set out to sell the $666 Apple-1 computer.

Apple will not officially become a corporation until January 3 the following year. By that time, Wayne is no longer a part of the business.

August 3, 1977: The first affordable, mass-market personal computer makes its debut… and, contrary to what you might think, it’s not the Apple II.

Although Tandy’s TRS-80 arrived the year after the Apple I and a few months after the Apple II, it proved to be the first “Apple killer” on the market: pre-dating later rivals like IBM as Apple’s first big tech industry opponent. And, for the longest time, it seemed to be on course to win…

July 20, 1978: Apple DOS makes its debut on the Apple II, giving Apple its first official operating system.

A command line interface with green text prompts on a black background, Apple DOS looks incredibly primitive next to today’s graphical user interfaces. Nonetheless, for Apple users this was the macOS Sierra of its day.

July 1, 1976: The Apple 1 goes on sale, becoming the first computer ever sold by the Apple Computer Company.

Arriving the same month Jimmy Carter was nominated for U.S. president, Family Feud debuted on TV, and the United States celebrated the 200th anniversary of its Declaration of Independence, the Apple 1 is only produced in small numbers, and sells for the unusual price of $666.66.