Washington: 'Game of Thrones' author George R.R. Martin writes his bestselling books in the Wordstar 4.0 program that he refers to as his "secret weapon".

During his appearance on 'Conan', the 65-year-old author said that he doesn't have to worry about spell check in the primitive 1980's technology, which is a great help when he has to type in words such as 'Baratheon' or 'Targaryen', ABC News reported.