The Apple II was introduced on April 16, 1977 at the first West Coast Computer Faire. It differed from its major rivals, the TRS-80 and Commodore PET, because it came with color graphics and an open architecture. While early models used ordinary cassette tapes as storage devices, they were superseded by the introduction of a 5 1/4 inch floppy disk drive and interface, the Disk II.
The Apple II was chosen to be the desktop platform for the first "killer app" of the business world—the VisiCalc spreadsheet program. VisiCalc created a business market for the Apple II, and gave home users an additional reason to buy an Apple II—compatibility with the office. According to Brian Bagnall, Apple exaggerated its sales figures and was a distant third place to Commodore and Tandy until VisiCalc came along.
By the end of the 1970s, Apple had a staff of computer designers and a production line. The Apple II was succeeded by the Apple III in May 1980 as the company competed with IBM and Microsoft in the business and corporate computing market.
Jobs and several Apple employees including Jef Raskin visited Xerox PARC in December 1979 to see the Xerox Alto. Xerox granted Apple engineers three days of access to the PARC facilities in return for the option to buy 100,000 shares of apple at the pre-IPO price of $10 a share.
Jobs was immediately convinced that all future computers would use a graphical user interface (GUI), and development of a GUI began for the Apple Lisa.
In December 1980, Apple launched the initial public offering of its stock to the investing public. When Apple went public, it generated more capital than any IPO since Ford Motor Company in 1956 and instantly created more millionaires (about 300) than any company in history. Several venture capitalists cashed out, reaping billions in long-term capital gains.