Can I disable anti-aliasing in Photoshop?
To the best of my knowledge... Photoshop doesn't anti-alias most things. (I believe font layers are... but that's another subject) I believe you're referring to "feathered edges" or are working with "semi-transparent areas". You either need to remove the alpha-channel from the layer... (meaning no transparency) or be sure not to use tools that select/create soft-edges or have a feathered edge.