From James Gleick, Genius. Richard Feynman and Modern Physics: "Weiner remarked that Feynman's notes represented 'a record of day-to-day work,' and Feynman reacted sharply. 'I actually did the work on paper,' he said. 'Well, said Weiner, 'the work was done in your head, but the record of it is still here.' 'No, it's not a record, not really. It's working. You have to work on paper, and this is paper. Okay?'"
Actually, the quotation, which I have not checked yet, comes from Merlin Donald, A Mind so Rare: The Evolution of Consciousness (New York: W.W. Norton, 2001), p. 301, a book I am reading at the moment. Donald uses this passage to illustrate his point that our memories do not just reside in our brains, but also in external artifacts, based on "symbolic technology." These artifacts "liberate consciousness from the limitations of the brain's biological memory systems. The new physical media of symbolic technology have enormous advantages over brain-based memory media. One of their chief advantages ... is that they are fully accessible by awareness. ... Because of the limitations of biological memory, conscious thought was enormously difficult when contained entirely within the brain box. External storage changed this and gave thinkers new strategic options" (305).
Paper has certain advantages as a medium of external memory storage, computer programs have others and more—or so I would think. But however that may be, the book is a fascinating read.