Al Shugart, a pioneer in the computer disk drive industry and one of Silicon Valley’s most colorful entrepreneurs, has died. He was 76. The founder of Seagate Technology, now the world’s largest maker of computer disk drives, died on Tuesday following complications from heart surgery, said Julie Still, a family friend and Seagate spokeswoman. Shugart, who once ran his dog Ernest as a candidate for Congress, was beloved at Seagate for his coach mentality in grooming young executives, despite a sometimes gruff manner.