The machine, which he bought in a Tennessee pawnshop for $50 in 1963, is beginning to betray understandable symptoms of old age and hard usage. If the Lettera 32 had hooves, it would have been dragged out to meet the bolt gun years ago.

"It has never been serviced or cleaned other than blowing out the dust with a service station hose," said the writer. "I have typed on this typewriter every book I have written including three not published. Including all drafts and correspondence, I would put this at about 5m words over a period of 50 years."

When a friend offered to buy the 76-year-old Pulitzer-prizewinner a replacement, McCarthy volunteered to auction his machine and has promised the proceeds to the Santa Fe Institute, a "transdisciplinary research community" dedicated to expanding the boundaries of scientific understanding.

The Pulitzer prize-winning author's notes, handwritten drafts and correspondence for each of his 10 novels are included in the archive at the Southwestern Writers Collection at Texas State University-San Marcos. Also featured in the 98-box archive, which spans McCarthy's literary career from 1964 to 2007, is his 1994 play The Stonemason, about an African-American family in Louisville, Kentucky, and four screenplays, including No Country for Old Men – which McCarthy started as a screenplay in 1984 and adapted into a novel 20 years later.

The author, who guards his privacy carefully, admitted in a rare interview with the New York Times in 1992 that he'd sent his debut The Orchard Keeper to Random House because "it was the only publisher I had heard of". Letters in the archive show McCarthy expressing his gladness that the "book is acceptable to [Random House]", and discussing inconsistencies and changes that needed to be made to the book.

Known for his rural settings, biblical prose and affinity for bygone worlds, McCarthy said that while typically he doesn't know where the ideas for his books originate, he can trace "The Road" to a trip he took with his young son to El Paso, Texas, about four years ago. There, standing at the window of a hotel in the middle of the night, his son asleep nearby, he started to imagine what El Paso might look like 50 or 100 years in the future.

"I just had this image of these fires up on the hill ... and I thought a lot about my little boy," said McCarthy, whose previous books include "Blood Meridian" and "All the Pretty Horses." He said he wrote some of his thoughts down and didn't really think about it again until he was in Ireland a few years later and the novel came to him. "There was a book, and it was about that man and that little boy," he said.

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Having a child as an older man also had its effect on McCarthy. "It wrenches you up out of your nap and makes you look at things fresh," he said. "It forces the world on you, and I think it's a good thing." Winfrey was clearly fascinated with McCarthy's life, particularly the time when he was so poor that he once was tossed out of a $40-a month hotel because he couldn't pay his bill. He told a story of living in a "shack in Tennessee," having so little money that he could not afford to buy toothpaste when he ran out, only to discover a free sample of toothpaste in his mailbox. "Just when things were really, really bleak something would happen," he said.

Many authors jump or weep for joy upon receiving the word from Winfrey, publishing's swiftest and surest path to the top of best seller lists. But McCarthy's apparent indifference to having hundreds of thousands of new readers baffled and charmed the talk show host. "You are a different kind of author, let me tell you," she said, chuckling.