Joysticks:

Pressure-sensitive joysticks have a non-movable stick (isometric joysticks). In case of pressure sensitive joystick, strain gauges are utilized to measure the pressure and convert it into movement of the cursor in the specified direction.

Two thumbwheels are usually needed to control the screen cursor in its horizontal and vertical position respectively.

As the name implies, a trackball is a ball that may be rotated with the fingers or palm of the hand to produce screen-cursor movement. Potentiometers, associated to the ball, are used to measure the direction and amount of rotation. Trackballs are frequently mounted on keyboards or other devices such like the Z mouse as described earlier.

While a trackball is a two-dimensional positioning device, a spaceball gives six degrees of freedom. Unlike any trackball, a spaceball does not move in fact. The amount of pressure applied to the spaceball is measured by the strain gauges and it is to provide input for spatial positioning and orientation as the ball is pushed or pulled in several directions. Spaceballs are utilized for three-dimensional positioning & selection operations in virtual-reality systems, animation, modeling,  CAD and other applications.