The knobs (or control dials) are used to send digital information to the computer. As a knob is turned, a succession of numbers are available for use by the computer. The knobs can be used to rotate a displayed object about the x, y, or z axis, translate the object along the x or y axis, and change the size of the view. Action performed by these knobs is continuous and is initiated by turning the knob in the proper direction and terminated by turning the knob in the opposite direction.