Abstract: A system and apparatus for collecting response data. A response unit is provided having a dial, keypad, and a biconditional response mechanism. The response unit operates in two modes, a dial mode and a keypad mode. Mode is determined by the power supplied to the response unit. If the power supply supplies a first voltage, the response unit will be in one mode, and if the power supply supplies a second voltage, the response unit will be in a second mode. In dial mode, the keypad is inactive. The response unit sources a voltage along a continuum based on the positioning of the dial. The biconditional response mechanism may also be active and when activated, causes the response unit to source an analog voltage outside the dial's continuum. In keypad mode, the dial is inactive, and each key of the keypad is associated with a unique voltage within a voltage range such that pressing a key causes the associated voltage to be sourced by the response unit.