VisiCalc

VisiCalc ("visible calculator") is the first spreadsheet computer program for personal computers, originally released for the Apple II by VisiCorp on October 17, 1979. It is considered the killer application for the Apple II, turning the microcomputer from a hobby for computer enthusiasts into a serious business tool, and then prompting IBM to introduce the IBM PC two years later. More than 700,000 copies were sold in six years, and up to 1 million copies over its history. Initially developed for the Apple II computer using a 6502 assembler running on the Multics time-sharing system, VisiCalc was ported to numerous platforms, both 8-bit and some of the early 16-bit systems. To do this, the company developed porting platforms that produced bug compatible versions. The company took the same approach when the IBM PC was launched, producing a product that was essentially identical to the original 8-bit Apple II version. Sales were initially brisk, with about 300,000 copies sold. VisiCalc uses the A1 notation in formulas. When Lotus 1-2-3 was launched in 1983, taking full advantage of the larger memory capacity (up to 256 KB) and 80-column screen of the IBM PC, versus 64 KB on the 40-column Apple II Plus, VisiCalc sales declined so rapidly that the company was soon insolvent. In 1985, Lotus Development purchased the company and ended sales of VisiCalc.