Slice apples into pie shell, pour the half cup sugar over the apples, sprinkle with cinnamon.
For the topping, mix flour and sugar. Cut in margarine until crumbly. Spread over the top of the pie. Bake at 350 degrees for 60 minutes, until topping starts to brown just slightly. Cover the edge of the crust with foil when baking. Remove after 45 minutes in the oven so it can brown slightly before finished baking.