Game of Thrones creator George R.R. Martin explained to Conan O'Brien why he writes his Song of Ice and Fire series on an antiquated DOS machine.

DOS, no less! Game of Thrones creator George R.R. Martin sat down with Conan O'Brien on Tuesday, May 13, and explained why he uses antiquated word processing system WordStar 4.0 on a DOS machine to write his Song of Ice and Fire series.

"I have a secret weapon," Martin, 65, told the late night host. "I actually have TWO computers." The novelist went on to explain: "I have a computer I browse the Internet with, and I get my email on, and I do my taxes on."

For writing, though, Martin prefers a less-sophisticated, nearly-obsolete disk operating system from the '80s. "Then I have my writing computer, which is a DOS machine—not connected to the Internet… Remember DOS? I use WordStar 4.0 as my word processing system."

Martin, who started writing the Song of Ice and Fire series back in 1991, further explained: "It does everything I want a word processing program to do, and it doesn't do anything else." Venting his frustration over autocorrect and spellcheck, Martin added, "I don't want any help, where you type a lower case letter and you want a capital. I don't want a capital." The author said with a chuckle, "If I wanted a capital, I would have typed a capital. I know how to work the shift key."

He also noted how much he dislikes spellcheck—and no wonder! His characters include Daenerys Targaryen, Tyrion Lannister, and Cersei Baratheon.

Game of Thrones fans also should not blame DOS if the smash HBO series ends up lapping the actual book series. Martin, the screenwriter of the show, has yet to crank out the sixth and seventh books—a fact he reaffirmed to TMZ on Wednesday, May 14.

"Who the hell knows?" Martin said of what would happen if that was the case. "I'm not even working on the last book yet, I'm working on the next book… One page at a time."