Abstract: An improved controller for use in adjusting certain electrical and other values, such as a pair of electrical signals which can be used to actuate a circuit for performing a specific function, such as moving the cursor of a CRT display of a computer. The mechanism includes a rotatable shaft having a cylinder mounted thereon. The cylinder moves with the shaft as the shaft rotates, and the cylinder can move longitudinally of and relative to the shaft. A first encoder responsive to the rotation of the shaft is used to adjust a first electrical signal; and a second encoder responsive to the linear motion of the cylinder relative to the shaft is used to adjust a second electrical signal. When the first and second signals are applied to the mouse inputs of a computer, the cursor on the CRT display of the computer can be shifted around as a function of the rotation of the shaft and the linear motion of the cylinder. Other types of apparatus can be controlled by the mechanism.