1. A bank note processing machine comprising: sensors, a transport system including a singling unit and at least one stacking unit, an input/output device; a control device with an associated memory which controls the elements of the bank note processing machine by means of software and/or data stored in the memory; and an interface which makes it possible to couple memory systems of different kinds to the bank note processing machine in order to alter, supplement or replace the software and/or data stored in the memory; wherein the memory system has a drive and a storage medium which are suitable for optical and/or magnetic recording; wherein the transport system transports single bank notes singled by the singling unit along the sensors to the at least one stacking unit according to an evaluation of data obtained by the sensors by the control device; and wherein data obtained in the bank note processing machine during operation are stored in the memory system.