John Warnock, who helped invent the PDF and co-founded Adobe Systems, dies at age 82

John Warnock, who helped invent the PDF and co-founded Adobe Systems, has died. He was 82. The company said in a statement that the Silicon Valley entrepreneur and computer scientist died Saturday surrounded by family. It didn't give the cause of death or say where Warnock died. Warnock was working at Xerox in the late 1970s when he came up with a printing and graphics protocol. When Xerox balked, Warnock and colleague Charles Geschke created their own company, Adobe Systems. Software created by Adobe also includes Adobe Illustrator and Photoshop. Warnock is survived by his wife and their three children.