Mix sugar with the cinnamon and salt. Arrange yams in layer in a rectangle Pirex dish , Sprinkle between the layers the sugar and cinnamon. Dot on top the butter, and pour over all the orange juice. Cover with nylon wrap, and Micro on high for 10 minutes. Bake in pre heated 350 F hot oven , uncovered for 35- 45 minutes, till it become nicely brown color, You should baste from time to time. Yamy, Yamy.