Martin and Steel (in 1987?) showed that if there are infinite many Woodin cardinals then every projective set of reals is determined (PD). However, it is mentioned in many texts that in 1983/1984 Woodin proved PD from a very strong large cardinal axiom, I0. It is also said the proof is quite different from Martin-Steel's proof. I would like to know a sketch of Woodin's proof. Thank you.