The Cab06 uses a more conventional knob for speed control and is available with either a potentiometer (Cab06p) or digital encoder (Cab06). Both varieties of the Cab06 can be set to YARD mode. Yard mode makes the speed knob act as a "center off" speed control. Turn the knob to the right and the loco will increase speed in the forward direction. Turn it to the left and speed will decrease until it gets to zero then it will start to increase speed in the reverse direction the farther you turn it to the left.
The chip included with the Cab06 Throttle is an upgrade for older PH-Pro 5 amp Command Stations made prior to 3/2007. If you have a Powercab, SB3, SB3a, or an SB5 you do not need this chip.