In the early ’80s Steve Jobs needed help from Bill Gates: Apple was developing its first Macintosh. Microsoft, which had supplied IBM with the MS-DOS operating system for its PCs, was invited to be the Mac’s first software developer. Early Mac developer Andy Hertzfeld says that when Jobs recruited Microsoft he feared it “might try to copy our ideas into a PC. Steve made Microsoft promise not to ship any software that used a mouse – until at least one year after the first shipment of the Macintosh”.
In 1983, Microsoft sprang a surprise with a new operating system for PCs using an interface like the Mac’s – Windows. Jobs “went ballistic”, demanding an explanation and saying: “I want him in this room by tomorrow afternoon, or else.”
Gates arrived alone to find himself surrounded by 10 Apple employees. “You’re ripping us off,” Jobs shouted.
But Gates looked him in the eye, and said in his squeaky voice, “Well, Steve, I think there’s more than one way of looking at it. I think it’s more like we both had this rich neighbour named Xerox and I broke into his house to steal the TV set and found out that you had already stolen it.”
(http://www.mac-history.net/computer-history/2012-03-22/apple-and-xerox-…)