Abstract: A disc processor, such as a printer or a recorder, or a combination processor, has a robotic arm that will pick a compact disc to be processed from a storage stack and move it to a tray associated with the processor. The robotic arm includes a sensor to sense when a disc is in a position to be held in a picker on the arm. The sensor signal can be used for determining whether or not the stack of discs in the input bin is of the correct height; for determining whether or not more than one disc has been picked up by the handler; and also for determining the presence of a disc in the tray or held on the picker arm.