How do I turn off anti-aliasing while drawing shapes in Photoshop?
Firstly you set the shape mode to "fill pixels", you can't turn AA off with shape layers:
Secondly you need to uncheck the "Anti-alias" checkbox (this only appears after you do the first step)
Here I am zoomed in to 800%. The rectangle on the right was drawn with AA on, the rectangle on the left was drawn with AA off.