I wanted to try and make as few changes to Maher's listing as possible, so I had to use MODE 3, for its 80-column text display. (However, because there's less RAM available for BASIC programs in MODE 3, I did end up having to compress the main game listing using the good old Pack routine in the PRES Advanced BASIC Editor ROMs. If I hadn't, the program would have run on a Master 128 but would have been too big to run on a Model B.)
Here's some background on the program from a 1978 issue of Creative Computing magazine, where the Oregon Trail listing was first published, I believe:
By the way, this is the pre-dysentery version of the game.