CRT display due to the limited space in front of the computer, which left them at a disadvantage. To alleviate these problems, Saunders created a detached control device, essentially an early gamepad. The gamepad had a switch for turning left or right, another for forward thrust or hyperspace, and a torpedo launch button. The button was silent so that the opposing player would not have a warning that the player was attempting to fire a torpedo during a cooldown period. Development Russell, Graetz and Wiitanen developed the basic Spacewar! concept in the summer of 1961, in anticipation of the PDP-1 being installed. Russell had recently finished reading the Lensman series by E. E. "Doc" Smith and thought the stories would make a good basis for the program. "His heroes had a strong tendency to get pursued by the villain across the galaxy and have to invent their way out of their problem while they were being pursued. That sort of action was the thing that suggested Spacewar!. He had some very glowing descriptions of spaceship encounters and space fleet maneuvers." Other influences cited by fellow programmer Martin Graetz include E. E. Smith's Skylark novels and Japanese pulp fiction tokusatsu movies. For the first few months after its installation, the PDP-1 programming community at MIT focused on simpler programs to work out how to create software for the computer. During this period, Russell visited his old friends in the community frequently and described the Spacewar! concept to them. Russell hoped someone would implement the game, but had no plans to do so himself. Other members of the community felt he was the logical choice to create the game, however, and began pressuring him to program it. In response, Russell began providing various excuses as to why he could not do so. One of these was the lack of a trigonometric function routine needed to calculate the trajectories of the spacecraft. This prompted Alan Kotok of the TMRC to call DEC, who informed him that they had such a routine already written. Kotok drove to DEC to pick up a tape containing the code, slammed it down in front of Russell, and asked what other excuses he had. Russell, later explaining that "I looked around and I didn't find an excuse, so I had to settle down and do some figuring", started writing the code around the time that the PDP-1's display