Tim Hartnell (1951-1991) was an Australian journalist, self-taught programmer and extremely prolific, bestselling author of books and magazines on computer games. His company, Interface Publications (set up with Elizabeth North), produced titles for all of the machines in the home computer market, including Sinclair machines. Hartnell wrote several compendiums of computer games, which typically had several categories of games, with several games in each category. Each category had tips for writing enjoyable games in that genre. Each game had a description of the program and an explanation of its implementation, sometimes with ideas for modifications; this was followed by the raw code, which the reader had to enter into the computer. Some long games, such as Bannochburn Legacy, had more than 500 lines of code.