The system contained several educational programs, and Rawitsch's boss let him know that it was open to submissions. Rawitsch, with permission from Heinemann and Dillenberger, spent the 1974 Thanksgiving weekend copying and adjusting the printed BASIC source code into the system.[6][11][12] Rather than submit the recreated copy, he instead enhanced the game with research on the events of the Oregon Trail that he had not had time for with the original version, and changed the frequency and types of random events, such as bad weather or wagons breaking down, to be based on the actual historical probabilities for what happened to travelers on the trail at each location in the game. Rawitsch calculated the probabilities himself, basing them on historical diaries and narratives of people on the trail that he read.[5][11] He also added in more positive depictions of Native Americans, as his research indicated that many settlers received assistance from them along the trail.[8] He placed The Oregon Trail into the organization's time-sharing network in 1975, where it could be accessed by schools across Minnesota.[9][13]