January 2, 1979: Entrepreneurs Dan Bricklin and Bob Frankston incorporate their company Software Arts to publish a little program called VisiCalc.

The first spreadsheet software for the Apple II, the $100 VisiCalc ultimately becomes personal computing’s first “killer app.” It helps transform personal computers from “cool to have” toys into “must have” business accessories.

August 12, 1981: The launch of the IBM Personal Computer ignites a long-running Apple-versus-PC rivalry.

Secure in the Apple II’s technical superiority over the new PC, Apple welcomes International Business Machines to the personal computing party in a full-page ad in the pages of The Wall Street Journal. Things won’t stay positive for long.

June 10, 1977: Apple Computer Inc. ships its first Apple II computer.

A hulking beige mammoth with 4KB of RAM (upgradeable to a whopping 48KB), the Apple II was the computer that defined Apple for a generation of fans. Retailing at $1,298, it cost the equivalent of a handful of MacBook Pros today  — even though it seemed a total bargain at the time.