From The Name of the Rose, 1:
"I completed a translation, using some of those large notebooks from the Papeterie Joseph Gibert in which it is so pleasant to write if you use a felt-tip pen."
Eco has a converted church as his scriptorium. One floor has a computer, one has a typewriter, one in which he writes long-hand (so he write with whichever tool feels best today). - The source for this is currently mispaced. But the excellent 'A Conversation on Information' interview with Patrick Coppock from 1995 has a lot on computers, notebooks, and so on:
"As a writer I have discovered there are certain kinds of things for which I still need the pen, there are certain things for which I need the computer, certain things for which I need a felt-tipped pen. And the kind of instrument I am using is influencing my writing enormously."
Q: "The material substance that you operate with".
Yes, when I come to think about it, this kind of action... [Eco picks up his notepad and scribbles on it] ...is very important. And this is so new that people have not really understood those differences. I don't know [...]
Eco's critics on the tool, the hand and authenticity (viz Heidegger and Walter Benjamin):
So, there was a Metropolitan legend that said that my novels have been written at the computer, and they don't consider that The Name of the Rose was published in 1980, and that the first really good word-processors started to come in 1982-83. So it could not have been computer-written. [...]
Type-written or hand-written. But for the Pendulum, since the Pendulum speaks about the computer, the silly journalists argue that, well, "Your book was concocted by the computer." And they still believe that you put some words there, and zzzaapp: the machine gives you the book. One of them said: "Well, it is clear that this is computer-written, except one chapter. That one where the boy plays the trumpet in the cemetery (the final chapter). It's clear that that one is hand-written." It was the only chapter of my book that I wrote immediately, and without correction at the computer! All the others were hand-written! [...]
Put together in multiple ways. Why? Because I had in mind this final chapter right from the beginning. And I thought about it for eight years so intensely that when I arrived at this point - I remember very well, it was in my apartment in Bologna at 6 o'clock - it was like playing the piano, like a jazz-musician: I put it all down very easily with the computer, following my mind and only making the corrections underway. It was totally written at the computer...it was just because there was more inspiration, so to speak.
See also The World According to Eco ("Italian novelist and semiotician Umberto Eco expounds upon the Net, writing, The Osteria, libraries, the continental divide, Marshall Mcluhan,and, well, God").
More how we work.