Key dates in Apple history

The following are key dates in the history of Apple, whose co-founder and chief executive Steve Jobs announced Monday he was taking another medical leave of absence:

1976: Steve Jobs and Steve Wozniak unveil the first Apple computer in Palo Alto, California.It consists of little more than a circuit board and costs just under $700.

1977: The Apple II with a one-megahertz processor becomes the first mass produced computer and an instant hit.

1980: Apple becomes a publicly traded company.

1983: Lisa, the first personal computer featuring a mouse for navigating and desktop icons and folders, is introduced. Its failure is blamed on a daunting price of nearly $10,000.

1984: The Macintosh computer makes its debut. It is affordable and features innovations such as a disk drive, built-in monitor, and a mouse.

1985: Jobs resigns after being stripped of control of Apple in an internal power struggle.

1986: Apple chief executive John Sculley becomes company president. Jobs starts computer company NeXT and buys Lucasfilm's computer graphics division, renaming it Pixar.

1996: Apple buys NeXT and makes Jobs an Apple adviser.

1997: Jobs replaces Gil Amelio as head of Apple. Arch-rival Microsoft invests 150 million dollars in the company.

1998: Jobs revamps Apple's product line, churning out colorful $1,300 iMac desktop computers designed with monitors and drives in the same casing.

1999: The iBook, marketed as a mobile iMac, is introduced.

2001: Apple launches a portable MP3 digital music player, the iPod, for $399 and opens its first retail store in Palo Alto.

2003: Apple opens online music store iTunes.

2004: Jobs undergoes an operation for pancreatic cancer.

2007: Apple introduces the iPhone, launching the era of the touchscreen smartphone.

2009: Jobs goes on medical leave in January, returning to work in June after undergoing a liver transplant.

2010: Jobs unveils the iPad in January and the touchscreen tablet computer goes on sale in April, becoming a huge hit. Apple surpasses Microsoft in May as the largest US technology company in terms of market value.

2011: Jobs announces on January 17 that he is taking another medical leave of absence for unspecified health reasons.