It’s been such an uphill struggle for Marc Porat to sell the concept of intelligent agents at the company he founded, Sunnyvale-based General Magic Inc, that he wants someone else to have a go. He has stepped aside as chairman and chief executive in favor of Steve Markman, formerly head of products at Novell Inc, who takes both titles plus that of president. Porat stays on the board and is retained as an internal adviser; board member Roel Pieper admits that it was he that jogged Porat’s arm. Robert Kelsch, who joined from Northern Telecom Ltd to be president just three months ago, is leaving the company.