More than 25% of Apple IIs sold in 1979 were bought to run a single program.
The word referred to paper long before it referred to software. Since at least 1906, accountants used the term "spread sheet" to describe a grid of columns and rows in a ledger, so named because the oversized paper literally spread across two facing pages of a bound book.1
In 1978, Daniel Bricklin, a student at Harvard Business School, watched a professor erase and rewrite a financial model on a blackboard ruled into rows and columns. Bricklin realized a computer could recalculate every cell automatically. He recruited his former MIT classmate Bob Frankston, and the two built VisiCalc in the winter of 1978-79, working out of an apartment in Arlington, Massachusetts.2
VisiCalc went on sale in mid-1979 for under a hundred dollars. It ran only on the Apple II, and its effect on hardware sales was immediate. More than 25% of Apple IIs sold that year went to buyers who wanted the software, not the computer.3 John Markoff of the New York Times later described the Apple II as a "VisiCalc accessory." Steve Wozniak estimated that small businesses, not hobbyists, purchased 90% of Apple IIs.4
VisiCalc sold over 700,000 copies in six years. It did not survive the platform shift. When Mitch Kapor released Lotus 1-2-3 for the IBM PC in 1983, VisiCalc's sales collapsed within months. By 1985, Lotus had acquired the company that made VisiCalc, and the original program was discontinued.5
Microsoft released the first version of Excel for the Macintosh on September 30, 1985, then ported it to Windows in 1987. By the early 1990s, Excel had overtaken Lotus 1-2-3.6 Bricklin could not patent VisiCalc because software patents were not granted at the time. He was elected to the National Academy of Engineering in 2003 for the invention of the electronic spreadsheet.7