The chip was designed for Busicom, a Japanese calculator maker, by Federico Faggin, Ted Hoff, Stanley Mazor and Busicom's Masatoshi Shima. It held about 2,300 transistors and could run tens of thousands of instructions per second.
Intel bought back the rights to sell it to other companies, and its first advert announced "a new era of integrated electronics." Today's processors hold billions of transistors.
Source: Wikipedia