Platt, who died Thursday, started at Hewlett-Packard Co. in 1966 as an entry-level engineer and rose through the ranks to become executive vice president in 1987, and president and chief executive officer in 1992.
In 1993, he succeeded company co-founder David Packard as chairman of the board of directors. He retired in 1999, giving way to Carly Fiorina as chair and CEO of the Palo Alto, Calif., company.
That same year, he began serving on Boeing Co.s board of directors, and served as chairman from 2003 until June 2005. He also served as CEO of Kendall Jackson Wine Estates Ltd. from 2000 to 2001.
Jim McNerney, chairman, president and CEO of Boeing, credited Platt for his work during the Chicago-based companys recent difficult economic times.
"Lew shepherded Boeing with strength, grace, dignity and integrity through a period when the company most needed his steady hand," McNerney said in a statement. "He was a compassionate man who put his own retirement and personal plans on the back burner to ensure that Boeing never missed a beat through its recent recovery."
Mark Hurd, who took over the reins as president and CEO of HP in March after the board ousted Fiorina, noted Platts leadership and compassion during his 33 years with the technology company.
"Lew cared deeply for HP and its people, and his loss is being felt widely across our company," Hurd said in a statement. "He was a natural leader who was enormously well liked and made an enduring impression on those he encountered. The way he treated people and how he ran the company set an exceptionally high standard of personal decency."