Javier Marias gets it done with a typewriter and a stick in the eye to revisionists:
He writes with a typewriter, beginning with the first page, with a situation he has been brooding about, and some sense of the implications or characters involved, but no real storyline. He probes forward with this, discovering as he goes (he pointed out that the Latin root of “invent” also has the meaning “discover”), but here’s the thing: he does not ever go back and change what he has written. It’s a pact he has with himself. He must accept and work with what he has laid down as he goes. If he has had a character’s mother die at a particular time, he can’t alter that, even if becomes clear it would be convenient if she died earlier, or later. And writing as he does he has to remember just what he did say, so that later on he won’t violate it (without a “search” function on the typewriter; the new work is a trilogy some 1200 pages long.)
(via)
