11 years ago. Martin a few years ago gave an interview where he stated that he uses a modern PC now, assembled by one of his assistants (and I assume modern software).
"Well, he doesn’t actually write on an old DOS computer. He did write on an old DOS computer, and then it died. Actually, I built him the computer he writes on now, which is a state-of-the-art machine running DOS and WordStar 4.0." - GRRM's employee
https://www.lightspeedmagazine.com/nonfiction/interview-jame...