VisiCalc and the Birth of the Killer App

The spreadsheet that justified the purchase of a personal computer — and changed what software could be.

Before VisiCalc, the personal computer was a fascinating answer to a question most people had not asked. Dan Bricklin and Bob Frankston changed that in 1979 with a program that did something no ledger pad could: recalculate everything, instantly, when a single number changed.

Accountants and small-business owners bought Apple II machines specifically to run it. The phrase "killer app" enters the language here — software so useful that it sells the hardware underneath it.

What makes VisiCalc worth preserving is not nostalgia but lineage. Every spreadsheet since is a direct descendant: the grid of cells, the formula bar, the relative and absolute references. The conventions were set early, by a small team working within tight memory limits, and they have proven astonishingly durable.

The Foundation maintains running copies of VisiCalc across several platforms, alongside the documentation that taught a generation how to think in cells.