Platt, a 33-year veteran of HP,of a brain aneurism at the age of 64. He led the Silicon Valley icon as chief executive officer from 1992 to 1999, and subsequently became lead director of aerospace giant Boeing.
At the service, held at Stanford University Memorial Church, Boeing Chief Executive James McNerney spoke of Platt's integrity, sense of duty and warmth as a business leader.
"He regarded business leadership as a noble calling, as much an opportunity to do good as do well," McNerney said.
Platt, he said, was not afraid of sharp debate and delivering a tough message, but he also knew how to build consensus. Platt should be an example to the business world, which has been marred by scandal in recent years, McNerney said.
"No one was a better role model of what a business leader ought to be than Lew Platt," McNerney said, bringing applause from the crowd.
Dean Morton, former chief operating officer at HP and a close friend, recounted how Platt made genuine connections with people wherever he went, aided by a sharp wit and sense of humor.
Platt was in his prime when he died, which made his death a shock to all who knew him, Morton said. In addition to running Boeing's board, Platt had run a vineyard, was involved in numerous philanthropic foundations and traveled the world with his family.
"Lew was in full stride," Morton said. "In that sense, I'm sure that's the way he wanted to go."
Contributions in honor of Platt can be made at the Lewis Platt Memorial Fund at The Wharton School and the YMCA of the Mid-Peninsula in Palo Alto.